Year: 2016

 

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Minimally Invasive Techniques For the Private Practice Veterinarian: Laparoscopy and Video-Otoscopy

Clarence A. Rawlings, DVM, PhD, Diplomate ACVS University of Georgia, Athens, Ga

Another reference is Small Animal Endoscopy, edited by Todd R. Tams and Clarence A. Rawlings and published December 2010 by Elsevier. The text, illustrations, and case studies are much more complete, as well as having a website that includes movies of cases and techniques.

A wide variety of diagnostic and treatment procedures are accomplished using rigid endoscopy. Diagnostic veterinary laparoscopy and thoracoscopy are used to view the surface of organs and to selectively biopsy focal lesions. Multiple biopsies of an organ, or of multiple organs, can be safely taken and the severity of hemorrhage assessed. One of the most valuable uses is to diagnose and stage abdomfnal cancer. Few veterinarians enjoy performing euthanasia of a favorite client’s pet when confirming by laparotomy that an abdominal mass is a non-operable cancer in a patient with relatively mild signs and a good quality of life. The rationale for intra-operative euthanasia is that the stress of recovery from a laparotomy exceeds the expected extension of a quality life. In contrast, two small incisions for laparoscopy are usually sufficient to confirm the same diagnosis and prognosis. The pet with mild clinical signs can then be recovered with much less stress. Diagnostic procedures remain commendable indications, but the greater impetus for laparoscopy has been the development of treatments traditionally reserved for open laparotomy..

Minimally invasive veterinary surgery reduces the surgical insult and would seem to be preferred over traditional open approaches. Reduced stress and small incisions have produced quicker recovery, decreased complications, and reduced infection rates. Although research studies have documented decreased stress responses following minimally invasive surgery, the primary motivation for endoscopy is that we would want laparoscopy and other minimally invasive surgery for ourselves as we believe it to be less invasive. Clients frequently rationalize, “I want the same advanced medical/surgical treatment for my four-legged family member as I want for myself.” The list of endoscopic treatments is long and continually expanding. We are selective on when to apply a procedure, based on the patient’s disease and the goals of the client. Whenever, endoscopy is used as the initial surgical technique, the client should be informed that conversion to a traditional laparotomy is an option if the surgeon determines that laparoscopy provides inadequate exposure to complete the procedure. We add to our informed consent form the statement, “…….Has permission to convert to a traditional (open) procedure if deemed necessary during endoscopic surgery.” Few procedures are converted, but the ability to do so enforces the client’s perception of the advantages of endoscopy, avoids potential intra-operative delay to convert, and increases the range of procedures than can be attempted knowing that there is minimal increase in risk to the patient.

Endoscopic Treatments

• Laparoscopic Incisional Gastropexy (Preventative and Treatment)
• Laparoscopic Enterostomy Tube Placement
• Laparoscopic Cyptorchid Castration
• Laparoscopic Ovarioectomy/Ovariohysterectomy
• Laparoscopic Cystopexy for Retroflexed Bladder in Penneal Hernia
• Laparoscopic Cystoscopic Calculi & Polyp Removal
• Laparoscopic Colopexy for Recurrent Rectal Prolapse
• Laparoscopic Gastrostomy for Foreign Body Removal
• Laparoscopic Attenutation of Portosystemic Shunts
• Laparoscopic Intestinal Resection and Anatomoses (& Enterotomy)
• Laparoscopic Cholecystectomy & Adrenalectomy
• Thoracoscopic Pericardial Resection for Pericardial Effusion
• Thoracoscopic Lung Lobectomy
• Thoracoscopic Connection of Persistent Right Arotic Arch & PDA
• Thoracoscopic Thoracic Duct Ligation for Chylothorax
• Transcervical Insemination
• Cystoscopic Resection of Ectopic Ureter
• Cystoscopic Resection of TCC
• Cystoscopic Injection Augmentation for Incontinence
• Rhinoscopic Resection of Nasal Cancer
• Otoscopic Debridement of Middle Ear Inflammatory Disease (Dogs & Cats)
• Endoscopic FB removal

Specialized endoscopy veterinary equipment includes surgical telescopes, camera, camera processing unit, a video capture or digital capture record to document images, monitor for viewing images, light source and cable, insufflation equipment to inflate the abdomen with carbon dioxide, suction, irrigation, and electrocautery. Electrocautery can be either monopolar or bipolar. Other energy sources include the harmonic scape!, “tissue sealing” bipolar electrocautery (LigaSure and Force Triad), and diode lasers. These provide hemostasis and dissection capabilities. Staples and vascular clips can be applied to individual vessels or be used to appose tissue. The light source and camera are attached to the telescope and insufflation line is connected to a side port on the trocar that is inserted into the abdomen. It is preferable to attach the insufflation line away from the telescope port to reduce fogging of the scope. Most telescopes are 5 or 10 mm in diameter, but arthoscopes can be as small as 1.9 mm. A 30 degree scope is used for “side-angled” viewing and a O degree scope for “straight-on” viewing.

Laparoscopy requires the abdomen to be distended with an optical media (carbon dioxide gas) in order to illuminate and view the abdomen. To prevent carbon dioxide from escaping, air-tight trocars are used as portals for the telescope and surgical instrumentation. Instruments are either 5 or 10 mm in diameter.

Biopsy coreneedles can be placed separately in similar fashion as whenperforming ultrasound directedbiopsies, anddonotrequirea trocaras their opening is small and does not permit gas leakage from the abdomen. A wide variety of terminal instrumentation can be passed through the trocars for dissection, tissue manipulation, ligation, vascular clip application, cautery, suturing, biopsy, and stapling.

Organ Biopsies and Cancer Staging Using Laparoscopy Assistance

Peri–operative Care

Pre-operative examinations for laparoscopic diagnosis are the same as for traditional surgeries. Evaluation of patients, selection of anesthesia, and peri-operative management is case based, with less consideration given to whether the procedure is performed by laparotomy or laparoscopy. Dogs with bleeding tendencies are poor candidates for surgery and coagulograms are commonly performed prior to any biopsy. The presence of decreased coagulation function or likelihood of poor healing following surgery is a strong justification for laparoscopy as compared to laparotomy. Much less tissue injury is produced during veterinary laparoscopy, thus reducing the potential for life­ threatening hemorrhage. Likewise, the decreased openings into the abdominal require less healing. Another strong indication for laparoscopy versus laparotomy is the presence of ascites, particularly that of a high-protein ascites. Biopsies can be obtained laparoscopically on most organs in the presence of ascites, leaving the ascetic fluid in the patient. When these ascetic animals are explored during traditional laparotomy this fluid and protein are removed. The patient will then have to replenish this abdominal fluid, resulting in a need for more fluid and protein, frequently by plasma and colloid administration.

Supportive care considerations are the same as for traditional anesthesia and surgery, except that the stress is usually less. Postoperative analgesia dosages may be lower than for traditional surgeries. Trocar sites can be blocked with bupivacaine in order to provide local analgesia. Most patients resume normal body functions, such as eating, defecating and early activity, more quickly than after traditional laparotomy.

Laparoscopy as a Diagnostic Tool

Nearly every abdominal organ or mass can be examined and biopsied laparoscopically. The two-dimensional image and ability to place the “seeing-end” of the laparoscope next to a mass produces vastly superior images to that seen by the naked eye during a laparotomy. Thirty-degree telescopes can be very useful to see around organs and masses. Gravity is the best retractor and is extremely useful during laparoscopy. Not only is gravity a better retractor than a mechanical spreader or assistant’s hands, this gravity is more gentle to tissues. By positioning the patient such that the area to be viewed is superior, the other organs move away and permit better examination. This is in contrast to the use of self-retaining retractors and assistant’s hands during traditional laparotomy, both of which produce trauma and can obstruct the surgeon’s view. Two senses are reduced during laparoscopy as compared to laparotomy. First, depth perception is reduced as compared to laparotomy. This reduced depth perception can be partially compensated by moving the laparoscope in and out. Second, direct digital palpation (feel) is not routinely performed during laparoscopy and feel is usually transmitted through endoscopic surgical instruments such as a palpation probe.

Liver Biopsies: Many patients with generalized liver disease and those with focal disease can be best sampled during laparoscopy. Biopsies are larger and have a much greater diagnostic accuracy than those obtained with 16 g or smaller core biopsy needles. In addition multiple biopsies can be taken with large biopsy cup forceps increasing diagnostic accuracy. Increased hemostasis can be provided by using mono­ polar electrocautery through the biopsy forceps or by adding Gel-Foam to the biopsy site. Cysts and the gall bladder can be aspirated using a 18G needle. When possible, it better to pass the needle through the quadrate lobe prior to entering the gall bladder. A spring-fired 14 g biopsy needle can be used to obtain samples from deep masses, but the biopsy cup forceps is nearly always used as the liver architecture can be better evaluated. The ability to examine the surface of the liver provides the opportunity to selectively sample focal lesions. Positioning the patient on their back with their head slightly elevated, rotating the body from left to right, manipulation of the liver, and the use of a 30-degree scope provide superior external examination of the liver. In contrast, a quick and usually adequate sampling of generalized liver disease can be done during heavy sedation, possibly supplemented with propofol with the animal in left lateral recumbency. Although much of the liver surface can be examined, it is more difficult to palpate the liver or to determine reasons for dilation of the biliary system. Seldom is much diagnostic information gained by palpation of the liver during a traditional laparotomy.

Kidney Biopsies: Biopsies of both kidneys can be safely obtained using laparoscopy. The diagnostic quality is greater than that performed with ultrasound guidance. There are a much greater number of glomeruli obtained when laparoscopy is performed with 14 g core biopsy needles. The ability to selectively biopsy the more superficial cortex increases the likelihood of obtaining good glomeruli samples and avoids arcuate vessels. In addition to avoiding arcuate vessels, additional hemostasis can be obtained by compression of the biopsy site with a laparoscopic instrument. Focal lesions can also be sampled.

Intestinal Biopsies: Full-thickness intestinal biopsies can be obtained. These biopsies can be multiple and selected from throughout the gastrointestinal tract. If only mucosa! biopsies of the stomach duodenum, or colon are needed, flexible endoscopy is preferred. To obtain full thickness intestinal biopsies, the intestine is lifted to the abdominal surface for a laparoscopic-assisted biopsy. The biopsy sites can protected following laparoscopic surgery by suturing either omentum or an adjacent jejunum to the sites. When jejuna! patches are used, care must be taken to insure that any jejuna! patch is separated at least 45 cm from the biopsy site, in order to reduce the likelihood that a stick foreign body can not travel through an acute intestinal bend.

Pancreatic Biopsies: Many internists and pathologists believe that too few pancreases have biopsies taken. A biopsy has been shown to be required to differentiate acute necrotizing from chronic pancreatitis in the cat, in contrast to clinical signs, enzymes, and ultrasonography. Pancreatic biopsies are taken by either a biopsy cup forceps or by using a endo-loop about a tip of the pancreas, and then cutting the biopsy from the distal portion.

Other Biopsies: Biopsies can be obtained from the prostate, spleen, lymph nodes and a wide variety of abdominal structures.

Laparoscopy as a Staging Tool

Laparoscopy can be a quick, low-stress method to obtain a histologic diagnosis and determine spread of an abdominal mass. In patients that can be identified as having a non-treatable cancer, it is frequently possible for the patient to recover from a minimally invasive evaluation and enjoy a short period of good quality life. It is usually possible to obtain a biopsy using two 5 mm trocars. One trocar is for a 5 mm laparoscope and the other a biopsy cup forceps. An alternative is to use the second 5 mm trocar to pass a manipulating instrument to aid in positioning abdominal contents in order to use a 14 gauge core biopsy needle. The best method of activating the biopsy needle is with a double spring-fired device. Multiple biopsies should be obtained from the primary tumor and samples should be taken from the lymph nodes most likely to provide lymphatic drainage. Some lymph nodes, such as the medial iliac lymph nodes are commonly used as sentinel nodes and should be routinely sampled in patients with perinea! and pelvic masses, or suspected prostatic cancer. Liver, spleen, and kidneys should always be examined in an attempt to identify tumors on their surface. Patients with effusions, especially when being present in both the pleural and the peritoneal cavities may be candidates for mesothelioma or carcinomatosis. Multiple biopsies should be taken from serosal surfaces. During laparoscopy, we attempt to leave the ascetic fluid in the patient to avoid producing a requirement for fluid and protein shifts.

If the mass appears to be potentially respectable and there is no evidence of obvious spread, laparoscopy can be converted to laparotomy for tumor resection. During laparotomy these masses may be resected, or additional information gained during the laparotomy may produce the diagnosis that the cancer will not benefit from surgery. We try to error on the side of conversion for masses deemed potentially respectable based on laparoscopy. Many of these decisions are also influenced by the patient’s overall health and the client’s desires for quality of life.

Laparoscopy for Surgical Treatments

At least a dozen laparoscopic treatments have been developed and are being used clinically in small animal practices. See list above. Minimally invasive surgery reduces the surgical insult and would seem to be preferred over traditional open approaches for any operation that can be performed by laparoscopy. Minimally invasive veterinary surgery treatments have dramatically advanced patient care for people; companion animal practice is following this trend. An excellent introductory technique is to use two 5 mm trocars for identification and extraction of an abdominal cryptorchid testicle through the trocar site for castration. The spermatic cord is ligated and returned to the abdomen. The same trocar site can be used to remove a second testicle if it is also retained.

lncisional gastropexies are performed through one 10-12 mm trocar site and a second midline trocar for either a 5 or 10 mm laparoscope. (Fig. 2 and 3) This technique is strong, and easy to perform. The procedure was developed in research dogs and applied to a one-year prospective study of client-owned patients. Complications have been minimal; the gastropexy persists for a long time. Several hundred dogs have since been operated as well as many veterinarians being trained to perform the procedure. A trocar for insufflation and the laparoscope is placed on the midline, just caudal to the umbilicus. The second trocar is used for a 1O mm Babcock forceps and is placed lateral to the right edge of the rectus abdominus muscle and approximately 3 cm caudal to the last rib (Figure A). The antrum is lifted to the trocar site, which is lengthened sufficiently to perform an incisional gastropexy. The seromuscular layer of the antrum is sutured to the transverses abdominus (Figure B). Clients are urged to have an ultrasound examination performed within 6 to 12 months to insure that a gastropexy is present. Dogs with a gastropexy might bloat (gastric distention, only) and the appropriate treatment would be gastric decompression and fluid administration if volvulus is absent. In our prospective study, dogs had fewer gastric related signs after surgery than before gastropexy. Dogs with clinical signs of gastric dilation and volvulus also have been successfully treated laparoscopically.

Removal of cystic and urethral calculi using laparoscopic assistance to lift the bladder to the abdominal wall is very effective, reduces abdominal contamination with urine, and markedly improves ability to see the calculi and appearance of the bladder and urethra. Two trocars are used with the second site being enlarged just enough to lift the bladder to the abdominal wall. A mini-cystotomy is performed in order to place a 2.7 mm cystoscope. A variety of instruments are used to grasp and remove the calculi. The entire urethra can be examined to insure that all calculi are removed. To examined the male urethra, a 2.5 mm flexible scope is passed from the bladder antegrade into the urethra. This technique has been used to resect focal inflammatory polyps, to repair ruptured bladders, and to re-assess the sites of prior tumor resections. In similar laparoscopic-assisted fashion, foreign bodies have been removed from the stomach and intestines. Localized tumors and cecal-colic inversions have been resected with laparoscopic assistance.

Millions of ovariohysterectomies have been performed using traditional techniques in a similar fashion performed by James Harriot in the 1930’s. Recently, several laparoscopic and laparoscopic-assisted techniques have been developed to spay dogs and cats. Some studies have demonstrated that the stress response is reduced when the spay is done laparoscopically as compared to traditional surgery. I have recommended laparoscopic spays when other procedures (such as gastropexy) are being performed at the same time, in very large dogs, dogs with healing and coagulation deficits, and in dogs with residual ovaries. Other practitioners are routinely recommending that elective spays be performed routinely by laparoscopy. These include both ovariohysterectomies and ovariectomies. The latter is the standard procedure on the European continent and has been performed for decades with apparently no more problems that the traditional American ovariohysterectomy technique.

VIDEO-OTOSCOPY

Ear diseases are among the most common problems presented to the veterinarian. Dermatologists use the ear as a sentinel for generalized skin diseases, e.g. dietary based allergic dermatitis. Video-otoscopy is a vast improvement over traditional otoscopy as a diagnostic tool. The veterinarian can markedly improve your examination of the ear and equally important, the client can see and gain appreciation of the disease process. Practitioners using video otoscope daily strongly believe that client compliance is improved and that patients receive better ear care.

Ear Diagnostic Studies and Cleaning

Most ear diseases in dogs and cats are otitis externa, but otitis media must be rured out if topical treatment is to effectively treat otitis externa. Acute signs of otitis externa include hyperemia, edema, and excoriation. Chronic disease can lead to hyperplasia and even mineralization of the ear canal. Most patients have an abundance of smelly discharge and pruritus, as evidenced by head-shaking and pain. It is essential that a thorough dermatologic examination be done and the ear cleaned as the first step to ear treatment. Neurologic and otoscopic examinations are needed to rule out otitis media.

An ear swab for cystologic examination should be taken before ear cleaning. Cultures are commonly obtained. The exam should look for ear mites, foreign bodies, tumors, and character of the ear canal and tympanic member. Masses require either cytologic examination (fine needle aspirate, imprints of biopsies) or histopathology of biopsies. The cause of ear diseases can include infections (bacteria, yeast, fungi, viral, mites), foreign bodies (foxtail, plant, exudate), allergy (atopy, food, contact), endocrinopathies (hypothyroidism, sex hormone imbalances), seborrhea (primary, secondary), conformation (stenotic, hairy, polyps), immune mediated (pemphigus, lupus), and neoplasia (ceruminous gland T, squamous CC). Failure as a dermatologist frequently results in inappropriate or non-compliant treatment, e.g. failure of medical treatment and a need for surgery.

Since most ear dermatologic conditions have a secondary bacterial component and an allergic (or at least an excessive inflammatory) response, both antibiotics and corticosteroids are used topically. Antibiotics are given systemically when the middle ear is affected and systemic corticosteroids (anti-inflammatory dosage of 0.5 mg/kg for 5-10 days) are frequently needed to reduce inflammation. Fungal and mite infections require specific treatment. In general dry ears would require oily vehicles, but most are moist and exudative, thus requiring water-soluble vehicles. Eye medications may be used in the ear. All agents intended to treat specific agents must be administered to ears that have been just cleaned of debris if treatment is to be successful.

The most common explanation for treatment failure is to blame the client for not being compliant, but that may not be fair. Exudate must be removed initially by the veterinarian and then regularly before each treatment. Exudative processes may not be arrested and persistently insulate organisms from drugs. Conformational problems of pendulous ear pinnae and hairy canals and excessive moisture (swimming and pendulous ear canal) result in some breeds being very susceptible to ear disease.

Ear Diagnostic Studies and Cleaning

Indications to do a video otoscope are: 1. Owner’s comment about signs of ear disease, 2. Ear odor, discharge, or pain, 3. Older dogs undergoing a geriatric exam, 4. Breeds commonly effected by ear disease, and 5. Chronic skin disease. Video-otoscopy done in the outpatient room is typically done in the examination room with an awake or sedated patient. This is a cursory exam at the best and should be restricted to evaluating a healthy ear with no clinical signs. If the ear is found to be inflamed, painful, full of purelent material, etc. anesthesia is required to perform an thorough and diagnostic examination. The combination of anesthesia, improved video images, and irrigation through the scope increases visualization of the ear canal and tympanic membrane. It is the best technique to determine is otitis media is present. Undiagnosed and managed middle ear disease is a common cause for persistent otitis externa. In addition, failure to rid the ear of exudate makes it nearly impossible for medication to have an effect.

Instrumentation for video-otoscopy includes the standard camera/light/image processor endoscopy tower for use with a video-otoscope cone and with small diameter endoscopes. These can be the 1.9 and 2.7 endoscopes with their cystoscope sheaths. The scopes have a 30 degree viewing angle and the sheaths have an operating channel. Arthroscope sheaths also work well and provide excellent avenue for irrigation. Ancillary equipment include biopsy forceps, foreign body removal forceps, curets, ear loops, mosquito forceps, alligator forceps, and suction.

Clinical experience have shown that video-otoscopy is an excellent approach to manage middle ear disease by lavage and cleansing of the middle ear via the ruptured tympanic membrane. The approach requires persistent treatment by the client and regular video-otoscopy re-examinations.

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Recommended Reading

Cole TL, Center SA, Flood SN, et al: Diagnostic comparison of needle and wedge biopsy specimens of the liver in dogs and cats. J Am Vet Med Assoc 2002; 220: 1483- 1490.

Devitt, Chad M.; Cox, Ray E.; Hailey, Jim J: Duration, complications, stress, and pain of open ovariohysterectomy versus a simple method of laparoscopic-assisted ovariohysterectomy in dogs. Journal of the American Veterinary Medical Association 2005-09-15227:6, 921-927,

Evans SE, Bonczynski JJ, Broussard JD, et al: Comparison of endoscopic and full­ thickness biopsy specimens for diagnosis of inflammatory bowel disease and alimentary tract lymphoma in cats. J Am Vet Med Assoc 229: 1447-1450, 2006.

Freeman LJ, editor. Veterinary Endosurgery. St. Louis: Mosby, 1998. McCarthy TC, editor. Veterinary Endoscopy. Philadelphia: Saunders, 2004.

Goethem BV, Schaefers-Okkens A, Kirpensteijn J: Making a rational choice between ovariectomy and ovariohysterectomy in the dog: A discussion of the benefits of either technique. Veterinary Surgery. 2006: 35; 136.

Hancock RB, Lanz 01, Waldron DR, Duncan RB, Broadstone RV, Hendrix PK: Comparison of Postoperative Pain After Ovariohysterectomy by Harmonic Scalpel­ Assisted Laparoscopy Compared with Median Celiotomy and Ligation in Dogs. Vet Surg 2005: 34; 273.

Hernadez-Divers SJ, Rawlings CA: Rigid endoscopy in small and exotic animals. Vet

Med2003;98:640-643.

Rawlings CA, Foutz FL, Mahaffey MB, Howerth EW, Bement S, Canalis C: A rapid and strong laparoscopic-assisted gastropexy in dogs: Am J Vet Res. 62: 871-875, 2001.

Rawlings CA: Pearls of Veterinary Medicine: Laparoscopic Assisted Gastropexy. J Am Anim Hosp Assoc. 38: 15-19, 2002.

Rawlings CA, Howerth EW, Bement S, Canalis C: Laparoscopic-assisted enterostomy feeding tube placement and full-thickness biopsies with serosal patch in dogs. Am J Vet Res. 63: 1313-1319,2002.

Rawlings CA, Howerth EW, Mahaffey MB, Foutz TL, Bement S, Canalis C: Laparoscopic-assisted cystopexy in the dog. Am J Vet Res 63: 1226-1231, 2002.

Rawlings CA, Mahaffey MB, Bement S, Canalis C: Prospective evaluation of laparoscopic-assisted gastropexy in dogs susceptible to gastric dilatation. J Am Vet Med Assoc. 2002;221:1576-1581.

Rawlings CA, Barsanti JA, Mahaffey MB, Canalis C: Laparoscopic-assisted cystoscopy for removal of calculi in the dog. J Am Vet Med Assoc. 2003; 222: 759-761.

Rawlings CA, Diamond H, Howerth EW, Neuwirth L: Diagnostic quality of percutaneous kidney biopsies obtained with laparoscopy versus ultrasound guidance in dogs. J Am Vet Med Assoc. 2003; 223: 317-321.

Rawlings CA, Howerth EW: Obtaining Quality Biopsies of the Liver and Kidney. J Am Anim Hosp Assoc. 40: 352-358, 2004.

Saunders HM, Vanwinkle TJ, Drobatz Ket al: Ultrasonographic findings in cats with clinical, gross pathologic, and histologic evidence of acute pancreatic necrosis: 20 cases (1994- 2001). J Am Vet Med Assoc 2002; 221: 1724-1730.

 

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Making a Rational Choice Between Ovariectomy and Ovariohysterectomy in the Dog: A Discussion of the Benefits of Either Technique

BART VAN GOETHEM, DVM, AUKE SCHAEFERS-OKKENS, DVM, PhD, Diplomate ECAR, and JOLLE KIRPENSTEIJN, DVM, PhD, Diplomate ACVS & ECVS

Objective—To determine if ovariectomy (OVE) is a safe alternative to ovariohysterectomy (OVH) for canine gonadectomy.

Study Design—Literature review.

Methods—An on-line bibliographic search in MEDLINE and PubMed was performed in December 2004, covering the period 1969–2004. Relevant studies were compared and evaluated with regard to study design, surgical technique, and both short-term and long-term follow-up.

Conclusions—OVH is technically more complicated, time consuming, and is probably associated with greater morbidity (larger incision, more intraoperative trauma, increased discomfort) compared with OVE. No significant differences between techniques were observed for incidence of longterm urogenital problems, including endometritis/pyometra and urinary incontinence, making OVE the preferred method of gonadectomy in the healthy bitch.

Clinical Relevance—Canine OVE can replace OVH as the procedure of choice for routine neutering of healthy female dogs.

© Copyright 2006 by The American College of Veterinary Surgeons

 

INTRODUCTION

GONADECTOMY is one of the most frequently performed surgical techniques in veterinary practice because it is the most reliable means of pet population control.¹ The importance of pet population control is underscored by the American Humane Association’s Animal Shelter Reporting Study that between 3.9 and 5.9 million dogs are euthanatized annually in the United States.²

Gonadectomy can be performed by ovariectomy (OVE) or ovariohysterectomy (OVH), the latter being the preferred approach in the United States.³⁻⁵ This preference is most likely based on the presumption that future uterine pathology is prevented by removing the uterus. In The Netherlands and some other European countries, OVE is routinely performed and has replaced OVH as the standard approach for gonadectomy; the uterus is only removed when uterine pathology is present. Despite longterm studies that compare risks and complications associated with these techniques, and favor OVE as the preferred technique, OVE is not generally accepted in the United States.⁶⁻⁹

Our aim was to evaluate and report possible differences in surgical complications between OVE and OVH. We reviewed the veterinary literature for evidence that would identify whether either technique could be considered superior for routine neutering of dogs.

SURGICAL TECHNIQUE

OVE is started by a median celiotomy extending from the umbilicus to approximately halfway between umbilicus and os pubis, depending on dog size. In deep-chested or obese dogs, it is sometimes necessary to enlarge the incision cranially to allow sufficient exposure of the ovarian pedicle.⁴,¹⁰ The ovary was located, and retracted caudally to expose the suspensory ligament and ovarian pedicle. The suspensory ligament was stretched, broken, or transected by electrocoagulation or scissors, to improve manipulation and observation of the pedicle. The arteriovenous complex within the pedicle, arising from the ovarian artery and vein was ligated with 0-4/0 absorbable suture material, depending on pedicle size, after which it was transected. The uterine artery and vein were ligated at the cranial tip of the uterine horn, 5 mm caudal to the proper ligament, using 2/0-4/0 absorbable suture material, and transected at the proper ligament.¹¹ After excision, the ovarian bursa was opened and the ovary inspected to confirm complete ovarian removal.³,¹¹

OVH was also performed through a median celiotomy, although, based on the dog’s size and body condition, the incision was lengthened in a caudal direction. After the ovarian pedicles were ligated and severed, the broad ligament was examined. If it is vascular, it is ligated with 1 or 2 ligatures using 2/0-4/0 absorbable suture material before it is cut or torn. A clamp was placed on the uterine body just cranial to, or on, the cervix. The uterine arteries were individually ligated proximal to the clamp using 2/0-4/0 absorbable suture material and the uterus, was ligated circumferentially in the crushing groove that remains after removal of the clamp using 0-4/0 absorbable suture material. After inspection for potential bleeding at the ligated pedicles, the celiotomy was closed in layers.³,⁴,¹¹⁻¹³

From a technical perspective, OVE is a minimally invasive veterinary surgery and less time-consuming than OVH. Although it is possible to perform OVH through a small median celiotomy, atraumatic technique and correct placement of the uterine ligature near the cervix typically requires a larger celiotomy compared with OVE. Thus, the duration of surgery and anesthesia should be shorter for OVE, and because the celiotomy is shorter, the broad ligaments are not disrupted, and the uterine stump left intact, there should also be less surgical trauma resulting from the minimally invasive veterinary surgery.

INDICATIONS FOR OVE AND OVH

OVE, also known as laparoscopic spay, is the most commonly performed for elective neutering; however, it is also indicated for treatment of ovarian tumors, to promote involution of placental sites (non-responsive to medical treatment), to prevent recurrence of vaginal hyperplasia, to prevent hormonal changes that can interfere with medical therapy in patients with endocrine diseases (e.g., diabetes), and to eliminate the transfer of inherited diseases (e.g., generalized demodicosis).³,¹¹,¹⁴ OVE is also performed in young dogs ( ! 2.5 years) to decrease the incidence of mammary gland tumors. The relative risk for developing mammary gland tumors decreases when neutering is performed before first estrus (0.5%), between first and second estrus (8%), and between second estrus and 2.5 years of age (26%).¹⁵ Despite one contrary opinion,¹⁶ there is seemingly no benefit in performing OVH at the time of mammary tumor removal because neither tumor-related nor overall survival improve after OVH.¹⁷⁻¹⁹

OVH is the preferred laparoscopic spay treatment for most uterine diseases, including: congenital anomalies, pyometra, localized or diffuse cystic endometrial hyperplasia (CEH), uterine torsion, uterine prolapse, uterine rupture, and uterine neoplasia.³,⁴,¹¹,²⁰ In a study of 1712 canine OVHs, 1409 (82%) were performed for elective sterilization, and only 313 (18%) for reproductive tract disease (as adjunctive therapy for mammary neoplasia, for treatment of pyometra, endometrial hyperplasia, vaginitis, and several miscellaneous genital tract diseases).²¹ This and other reports clearly reflect textbook recommendations that the preferred technique for gonadectomy in dogs and cats is OVH.³⁻⁵,¹¹

SURGERY RELATED COMPLICATIONS

The primary rationale for selection of OVH or OVE is likely related to the expected frequency of short-term and long-term complications. In a retrospective study of 62 dogs that had OVH, 17.7% developed complications.22 Complications associated with OVE would be expected to be similar to those associated with the OVE component of OVH; however, other complications associated with removal of the uterus in OVH would not be expected with OVE. A review of reported complications after OVE and OVH is presented below (Table 1) and a logical decision for technique is suggested.

Intraabdominal Hemorrhage

Hemorrhage was the most common complication (79%) in dogs 425 kg in a review of 853 OVHs.¹⁰ Concurrently, hemorrhage has been determined to be the most common cause of death after OVH in large breed dogs.⁵,²⁰ Clinically important hemorrhage primarily occurs from the ovarian pedicles, the uterine vessels, or the uterine wall when ligatures are improperly placed,²³ and rarely occurs from vessels that accompany the suspensory ligament or within the broad ligament.⁴ Thus, comparing OVE with OVH, the likelihood of clinically important hemorrhage from the ovarian pedicles should be similar.

[table id=10 /]

Theoretically, OVH has additional risk for hemorrhage from vessels in the broad ligament and from uterine vessels near the cervix (where the uterine arteries are larger than at the tip of the uterine horn and bleeding can be more severe in comparison). Hemorrhage from uterine vessel rupture caused by excessive traction on the uterine body during OVH has been reported.²³

Vaginal Bleeding

Single nonabsorbable multifilament ligatures around the uterine body can predispose to erosion of uterine vessels, resulting in intermittent vaginal bleeding. Pearson reported vaginal bleeding in 11 (15%) of 72 dogs, 4–16 days after surgery.²³ Vaginal tamponade or exploratory celiotomy may be indicated, if the bleeding becomes severe. Vaginal hemorrhage may also be associated with infection caused by contamination during surgery, use of infected suture material, or from transfixation ligatures that enter the lumen of the uterus or cervix.²³

The advantage of ligating the uterine vessels at the uterine horn tip and transection at the proper ligament is that the uterine horn is not opened and the serosa remains intact. Bleeding from the vulva in the first week after surgery cannot occur. The only case in which one of the authors have observed a dog with vaginal bleeding after OVE was when the surgeon transected the uterine horn (and thus opened the lumen).

Ligation of the Ureter

Direct obstruction of a ureter occurs when the ureter is accidentally included in a ligature. For instance, if the pedicle is ligated too close to its base at the abdominal wall, because of inadequate exposure of the caudal pole of the kidney, the proximal aspect of the ureter may be incorporated.²⁰ More often the distal part of the ureter is involved because of its close location to the uterine body. Inadvertent, suture-associated occlusion of the distal ureter is more common if a distended urinary bladder displaces the trigone cranially.²⁰ Okkens et al⁸ reported complications after OVH in 109 dogs, admitted over a 2-year-period (1977–1979) at the University of Utrecht, The Netherlands. Among these dogs, 18 had signs related to the urinary system. Direct ligation of the ureter was observed at the ovarian pedicle in 2 dogs (11%) and at the distal ureter by uterine ligature in 3 dogs (17%). It is evident that the chance of ligation of the proximal ureter during OVE is identical to the OVH technique, but distal ureteral ligation is nonexistent during OVE.

Ovarian Remnant Syndrome

Recurrent estrus occurs after OVE or OVH when the ovaries are incompletely removed and residual ovarian tissue becomes functional. Collateral circulation to the ovarian tissue can develop even though the ovarian arteriovenous complex has been ligated and interrupted.³ In dogs, neither ectopic ovaries (ovarian tissue in an abnormal location such as in the mesentery), nor accessory ovarian tissue extending into the ligament of the ovary have been reported, in contrast to their occurrence in cats, cows, and humans.⁵,²⁴

Pearson²³ described 12 dogs with recurrent estrus in a group of 72 dogs with complications after OVH (17%). Okkens et al⁹ reported 109 dogs with complications after OVH, of which 55 dogs had complications of a gynecologic nature; residual ovarian tissue was observed in 47 dogs (43%). Of these dogs, 16 had bilateral, 25 rightsided, and 6 left-sided residual ovarian tissue. Ovarian remnants tend to be more commonly located on the right side. This higher frequency of right-sided ovarian remnants has been observed by others and is likely explained by a more cranial and deeper anatomic location of the right ovary, decreasing the ease of observation and removal.²³,²⁵ When performing OVE, the surgeon is placing 2 cuts close to the ovary (ovarian pedicle and proper ligament). One could argue, but this remains speculative, that there is an increased chance for ovarian remnants with OVE in comparison with OVH (where only 1 cut is made close to the ovary); however, this cannot be confirmed by literature review.

Most ovarian remnants occur after OVH.⁸,⁹,²³⁻²⁵ This may be because OVH is more commonly performed technique or because the celiotomy for OVH is located more caudally making observation of the (right) ovary more difficult. Decreased visualization enhances the chance for incorrect technique and the chance for ovarian remnants.10 In OVE, the incision can be positioned more cranial, avoiding this problem. Ovarian remnant syndrome can be avoided by correct surgical technique regardless of technique used. It is essential to have the incision cranial enough to allow complete visualization, especially of the right ovary. To achieve this with OVH a larger incision is necessary than for OVE.

Stump Granuloma

Inflammation and granuloma formation can be caused by ligatures of nonabsorbable suture material, poor aseptic technique, or excessive residual devitalized tissue (at the uterine body). Braided nonabsorbable suture materials, such as silk, nylon, or linen, and nonsurgical selflocking nylon bands (cable ties) have been implicated in most patients.²⁶ Okkens et al⁸ reported granulomas at the ovarian pedicle in 1 patient (6%) and at the uterine stump in 5 patients (28%). In dogs with gynecologic complications after OVH, Okkens et al⁹ observed 8 (15%) stump granuloma. The likelihood for development of a granuloma at the ovarian stump is not influenced by technique (OVE versus OVH), but the incidence of the more common granuloma at the uterine stump cannot occur with OVE. Granulomas at the uterine horn tip are possible, but to our knowledge, have not been described.

Fistulous tracts extending from the ligated ovarian pedicle can develop from inflammatory reaction to ligature material, primarily with braided nonabsorbable suture material. Ovarian pedicle granulomas were associated with sublumbar sinuses.²⁰ Pearson described 72 dogs with complications resulting from OVH at a time when nonabsorbable ligatures were routinely used, and reported 37 dogs with stump granuloma, of which 27 had sinus formation (38%).²³ In a report of 20 OVH-related fistulous tracts, the origin of the tract was unilaterally from an ovarian ligature in 12 animals and from the uterine ligature in 4 animals.⁵ Suture-associated fistulous tracts can easily be prevented by use of synthetic absorbable suture materials and surgical approach (OVE, OVH) should have no influence on occurrence of fistulous tracts.²⁶

Both OVE and OVH can result in fistulous tract formation from the ovarian stump. OVE technique might lead to formation of stump fistulas at the uterine horn tip; whereas, OVH technique has the additional risk for development of uterine stump fistulas. Both the uterine horn tip granuloma and the uterine horn tip fistula, however, can be prevented when correct OVE technique is used. Using correct technique, the uterine horn is not opened because transection is performed at the level of the proper ligament.

Miscellaneous

Many incidental complications after gonadectomy techniques including trauma to intestines or spleen, colonic incarceration,²³,²⁷ failure to remove gauze sponges from the abdomen before closure, endocrine alopecia, juvenile vulva formation, behavioral change, and eunuchoid syndrome have been reported.⁵ It seems unlikely that either technique will significantly increase the risk for any of these complications. Because OVE results in a smaller incision, complications such as incisional swelling, seroma, infection, dehiscence, delayed healing, ventral body wall dehiscence, self-inflicted trauma, and pain are expected to be less.

[table id=11 /]

LONG-TERM COMPLICATIONS AND UTERINE PATHOLOGY

When considering changing the routine neutering procedure from OVH to OVE, the importance of future complications and uterine pathology needs to be considered (Table 2). In particular, development of endometritis/pyometra, occurrence of neoplastic uterine changes, incontinence, and obesity should be considered.

Endometritis and Pyometra

Epidemiologic data for ~200,000 dogs covered by insurance in Sweden revealed that ~1800 nonspayed bitches were treated for pyometra in 1996. The risk of an intact bitch developing pyometra before 10 years of age was 23–24%.²⁸ Other studies, albeit on a smaller scale, had similar findings. Fukuda²⁹ reported a 15.2% chance for the development of pyometra in female dogs>4 years (n = 165) and Von Berky³⁰ reported a 14.9% chance for uterine disease (n = 175).

Thus, it is important to determine whether the uterus in ovariectomized dogs is predisposed to develop endometritis and pyometra. Pyometra has been defined as a hormonally mediated diestral disorder resulting from bacterial interaction with an abnormal uterine endometrial that has undergone pathologic changes assumed to be caused by an exaggerated response to progesterone stimulation.³¹ Recently, the concept of considering CEH– pyometra as a complex has been questioned. It has been suggested that 2 different disorders: one where CEH–endometritis appears to have a strong hormonal component and the other where pyometra might be more influenced by the bacterial component.²⁸ Nevertheless, both conditions are exclusively encountered in the luteal phase of the estrus cycle. Experimentally CEH or CEH–endometritis can be induced by administration of progesterone, even in ovariectomized bitches.²⁰ Withdrawal of progesterone treatment causes regression of the naturally occurring disease. Thus exposure to progestagen appears to be necessary for the development of CEH–endometritis.

A study by Okkens et al comparing the long-term effects of OVE versus OVH was conducted at the University of Utrecht in 1997.⁶ Questionnaires were sent to 264 owners of bitches that had either OVE (n = 126) or OVH (n = 138) performed for routine neutering 8–11 years earlier. Complete data were obtained for 69 OVE bitches and 66 OVH bitches. None of the OVE bitches had signs consistent with having had endometritis. With the exception of urinary incontinence, no other problems related to surgical neutering were identified. These findings agree with those of Janssens who performed OVE on 72 bitches and after a 6–10 year follow-up, no pyometra was detected.⁷ When OVE is correctly performed (all ovarian tissue removed), and in the absence of supplementation of exogenous progestagens, endometritis (CEH or pyometra) cannot occur.

Stump pyometra is uniquely associated with OVH, and can develop if endometrial tissue at the uterine stump is stimulated by either endogenous, because of incomplete ovarian tissue removal, or by exogenously administered progesterone.²⁰ In Okkens et al⁹ report on 55 dogs with gynecologic complications after OVH, 19 (35%) had stump pyometra associated with residual ovarian tissue. In the same study 47 bitches had histologically confirmed CEH–endometritis during celiotomy; abdominal exploration revealed the presence of residual ovarian tissue in all of these dogs. Another 7 dogs an enlarged and inflamed uterine stump, where no residual ovarian tissue was detected and on histology the inflammation was caused by an unabsorbed ligature (stump granuloma) without signs of CEH.⁹

These studies strongly suggest that progesterone is an essential factor in the occurrence of CEH–endometritis– pyometra and that correctly performed, OVH or OVE will prevent development CEH–pyometra in later life. OVE will not increase the chance for development of CEH–pyometra compared with OVH.

Uterine Tumor Formation

Uterine tumors are rare in the dog, with a reported rate of 0.4% of all canine tumours.³² The University of Pennsylvania Veterinary Hospital examined 33,570 female dogs between 1952 and 1966, and 96 gynecologic neoplasms (uterus, n = 11; vagina or vulva, n = 85) were detected in 90 dogs (0.27%).³³ This brings the overall chance for a uterine tumor to 0.03% (11/33570). Middleaged-to-older animals were most commonly affected and most canine uterine tumors were mesenchymal in origin. Of the uterine tumors, 85–90% were benign leiomyomas and 10% leiomyosarcomas. The true risk for development of malignant tumoral disease of the uterus is 0.003%. The prognosis associated with leiomyomas and other benign tumors is excellent because surgery is nearly always curative. For leiomyosarcomas and other malignant tumors, the prognosis remains good if there is no evidence of metastatic disease at surgery and complete excision is possible.³²,³⁴,³⁵ When performing gonadectomy, the surgeon has to balance the risk for possible tumoral development in the uterus when performing OVE, against the increase in surgery related complications when performing OVH.

Urinary Sphincter Mechanism Incontinence

Adhesions or granulomas of the uterine stump that interfere with urinary bladder sphincter function or development of a ureterovaginal fistula can occasionally cause incontinence. The most common cause of incontinence in spayed dogs, however, is urethral sphincter mechanism incompetence (USMI), an uncommon disease in intact bitches with reported incidences of 0.2% (10/ 5315)³⁶ to 0.3% (7/2434).²⁰ Because of the underlying hormonal cause, a significant increase of this pathology in spayed bitches has been hypothesized.³⁷,³⁸ Nickel et al³⁹ reported a significantly impaired urethral sphincter mechanism in gonadectomized dogs. In a retrospective investigation, Holt and Thrusfield³⁶ using data from a general and a referral practice in UK, reported that 3% (53/1681) and 17.7% (296/1681), respectively, of dogs were considered incontinent after OVH. In Switzerland, up to 20% (83/412) of spayed bitches developed signs suggestive of urinary incontinence postoperatively.³⁸ Confounding factors in the development of incontinence include time of OVH, body weight, breed of dogs and tail-docking.⁵,³⁶,⁴⁰⁻⁴³ An increased risk in tail-docked bitches has been documented raising the incidence to 1.3 (34/2614) compared with 0.7% (29/4382) for undocked dogs.³⁶

Long-term studies have been unable to detect a difference between occurrence of incontinence in dogs after OVE compared with OVH. One of the initial reports concluded that there was no difference between OVE and OVH.⁴⁴ Another study reported that 54 of 260 OVE dogs developed incontinence (20.8%) compared with 29 of 152 OVH dogs (19.1%); however, this difference was not significant.⁴⁵ Okkens et al⁶ reported urinary incontinence in 15 dogs (11%) after long-term follow-up but no significant difference in incidence between OVE and OVH neutered bitches.

Body Weight Gain

Gonadectomy adversely affects the ability to regulate food intake and thus predisposes these animals to obesity.²⁰,⁴⁶ Inactivity and increased food intake contributes to weight gains up to 38%. Edney and Smith⁴⁷ observed that 21.4% of all dogs were overweight and spayed females were twice as likely to be obese compared with intact bitches. In another study, where dogs were exercised regularly and their food intake was controlled, there was no significant increase in weight in either spayed or intact females.⁴⁸ No significant difference in weight gain has been observed between dogs that had OVE versus OVH in other studies.⁴⁹,⁵⁰

CONCLUSION

The absence of randomized studies comparing complications after OVE and OVH in dogs forces us to interpret historical reviews of both techniques. The rational conclusion after review, when immediate postoperative complications are considered, is that either technique can be used for canine female gonadectomy. The surgeon has to choose the least invasive, fastest, and safest procedure. A major advantage of OVE is that it can be performed through a smaller celiotomy and with less traction on the female genital tract. Technically, OVH is more complicated (more tissue is ligated and transected), time consuming (because a larger celiotomy is needed to expose the entire uterus) and is therefore expected to be associated with a greater short-term morbidity when compared with OVE. However, differences in short-term postoperative morbidity between the 2 techniques have not been published. Increased risk for surgery-related complications associated with OVH are estimated for: intraabdominal and vaginal bleeding (because of larger vessel diameter near the uterine body), ureteral ligation (because of close proximity of the distal part of the ureter to the uterine body), ovarian remnants (because of the more caudally located incision), uterine stump complications, and sinus tracts (because of mucosal exposure).

Since 1981, after introduction of OVE, a minimally invasive veterinary surgery, as a standard technique for canine neutering at Utrecht University, no increase in short-term complications has been observed. With respect to long-term urogenital problems, including endometritis/pyometra and urinary incontinence, it has been clearly established that they do not occur more frequently with either technique. The overall chance for development of malignant uterine tumors is very low (0.003%), and, in our opinion, does not warrant performing a potentially more traumatizing surgical procedure, OVH, that might be associated with more postoperative complications.

Without benefit of more prospective studies comparing surgical complications between OVE and OVH, most evidence extracted from the literature leads us to the conclusion that there is no benefit and thus no indication for removing the uterus during routine neutering in healthy bitches. Thus we believe that OVE should be the procedure of choice for canine gonadectomy.

REFERENCES

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2. Nassar R: Pet population dynamics and community planning for animal welfare and animal control. J Am Vet Med Assoc 198:1160–1164, 1991

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7. Janssens LA, Janssens GH: Bilateral flank ovariectomy in the dog – surgical technique and sequelae in 72 animals. J Small Anim Pract 32:249–252, 1991

8. Okkens AC, van de Gaag I, Biewenga WJ, et al: Urological complications following ovariohysterectomy in dogs. Tijdschr Diergeneeskd 106:1189–1198, 1981

9. Okkens AC, Dieleman SJ, van de Gaag I: Gynaecologische complicaties na ovariohysterectomy bij de hond ten gevolge van: 1. het incompleet verwijderen van de ovaria en 2. een ontsteking van de uterus-cervix stomp. Tijdschr Diergeneeskd 106:1142–1158, 1981

10. Berzon JL: Complications of elective ovariohysterectomies in the dog and the cat at a teaching institution: clinical review of 853 cases. Vet Surg 8:89–91, 1979

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13. Toombs JP, Clarke KM: Basic operative techniques, in Slatter D (eds): Textbook of Small Animal Surgery (ed 3). Philadelphia, PA, Saunders, 2003, pp 208–212

14. Wheeler SL, Magne ML, Kaufmann J: Postpartum disorders in the bitch: a Review. Compend Contin Educ Pract Vet 6:493, 1984

15. Schneider R, Dorn CR, Taylor DO: Factors influencing canine mammary cancer development and postsurgical survival. J Natl Cancer Inst 43:1249–1261, 1969

16. Sorenmo KU, Shofer FS: Goldschmidt: effect of spaying and timing of spaying on survival of dogs with mammary carcinoma. J Vet Intern Med 14:266–270, 2000

17. Philibert JC, Snyder PW, Glickman N, et al: Influence of host factors on survival in dogs with malignant mammary gland tumors. J Vet Intern Med 17:102–106, 2003

18. Morris JS, Dobson JM, Bostock DE, et al: Effect of ovariohysterectomy in bitches with mammary neoplasms. Vet Rec 142:656–658, 1998

19. Yamagami T, Kobayashi T, Takahashi K, et al: Prognosis for canine malignant mammary tumors based on TNM and histologic classification. J Vet Med Sci 58:1079–1083, 1996

20. Kyles AE, Aronsohn M, Stone EA, et al: Urogenital surgery, in Lipowitz AJ, et al. (eds): Complications in Small Animal Surgery. Baltimore, MD, Williams & Wilkins, 1996, pp 496–503

21. Wilson GP, Hayes HM: Ovariohysterectomy in the dog and cat, in Bojrab MJ (eds): Current techniques in small animal surgery (ed 2). Philadelphia, PA, Lea & Febinger, 1983, pp 334–338

22. Pollari FL, Bonnett BN, Bamsey SC, et al: Postoperative complications of elective surgeries in dogs and cats determined by examining electronic and paper medical records. J Am Vet Med Assoc 208:1882, 1996

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24. Miller DM: Ovarian remnant syndrome in dogs and cats: 46 cases (1988–1992). J Vet Diagn Invest 7:572–574, 1995

25. Wallace MS: The ovarian remnant syndrome in the bitch and the queen. Vet Clin North Am Small Anim Pract 21:501– 507, 1991

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27. Coolman BR, Maretta SM, Dudley MB, et al: Partial colonic obstruction following ovariohysterectomy: a report of three cases. J Am Anim Hosp Assoc 35:169–172, 1999

28. Fransson BA, Ragle CA: Canine pyometra: an update on pathogenesis and treatment. Compend Contin Educ Pract Vet 25:602–612, 2003

29. Fukuda S: Incidence of pyometra in colony-raised beagle dogs. Exp Anim 50:325–329, 2001

30. Von Berky AG, Townsend WL: The relationship between the prevalence of uterine lesions and the use of medroxyprogesterone acetate for canine population control. Aust Vet J 70:249–250, 1993

31. Nelson RW, Feldman EC: Pyometra. Vet Clin North Am Small Anim Pract 16:561–576, 1986

32. Klein MK: Tumors of the female reproductive system, in Withrow SJ (eds): Small Animal Clinical Oncology (ed 2). Philadelphia, PA, Saunders, 1996, pp 351

33. Brodey RS: Neoplasms of the canine uterus, vagina and vulva: a clinicopathologic survey of 90 cases. J Am Vet Med Assoc 151:1294–1307, 1967

34. Vos JH: Uterine and cervical carcinomas in five dogs. J Vet Med 35:385–390, 1980

35. Ogilvie GK, Moore AS: Tumors of the reproductive system, in Managing the veterinary cancer patient. New Jersey, Veterinary Learning Systems Co., Inc, 1995, pp 419–420

36. Holt PE, Thrusfield MV: Association in bitches between breed, size, neutering and docking, and acquired urinary incontinence due to incompetence of the urethral sphincter mechanism. Vet Rec 133:177–180, 1993

37. Thrusfield MV: Associations between urinary incontinence and spaying in bitches. Vet Rec 116:695, 1985

38. Arnold S: Harninkontinenz bei kastrierten Hu¨ndinnen. Teil 1: Bedeutung, Klinik und A¨tiopathogenese. Schweiz Arch Tierheilkd 139:271–276, 1997

39. Nickel RF, Van Wees AM, Van Den Brom WE, et al: Changes in urethral closure and bladder storage function in young female dogs caused by prepubertal events, the estrous cycle, and neutering, PhD Dissertation, RF Nickel, RU Utrecht, Chapter 7, pp. 87–110.

40. Janssens LA, Peeters S: Comparison between stress incontinence in women and sphincter mechanism incompetence in the female dog. Vet Rec 141:620–625, 1997

White RN: Urethropexy for the management of urethral sphincter mechanism incompetence in the bitch. J Small Anim Pract 42:481–486 42. Blendinger C, Blendinger K, Bostedt H: Die Harninkontinenz nach Kastration bei der Hu¨ndin. 1. Mitteilung: entstehung, Ha¨ufigkeit und Disposition. Tiera¨rztl Prax Ausg K Klientiere Heimtiere 23:291–299, 1995 43. Spain CV, Scarlett JM, Houpt KA: Long-term risks and benefits of early-age gonadectomy in dogs. J Am Vet Med Assoc 224:380–387, 2004 44. Ruckstuhl B: Die incontinentia urinae bei der Hu¨ndin als Spa¨tfolge der Kastration. Schweiz Arch Tierheilkd 120:143–148, 1978 45. Arnold S, Arnold P, Hubler M, et al: Incontinentia Urinae bei der kastrierten Hu¨ndin: ha¨ufigkeit und Rassedisposition. Schweiz Arch Tierheilkd 131:259–263, 1989

46. Salmeri KR, Olson PN, Bloomberg MS: Elective gonadectomy in dogs: a review. J Am Vet Med Assoc 198:1183– 1192, 1991

47. Edney AT, Smith PM: Study of obesity in dogs visiting veterinary practices in the United Kingdom. Vet Rec 118:391– 396, 1986

48. Le Roux PH: Thyroid status, oestradiol level, work performance and body mass of ovariectomized bitches and bitches bearing ovarian autotransplants in the stomach wall. J S Afr Vet Assoc 54:115, 1983

49. Houpt KA, Hintz HF: Obesity in dogs. Canine Pract 5:54–58, 1978

50. Houpt KA, Coren B, Hintz HF, et al: Effect of sex and reproductive status on sucrose preference, food intake, and body weight of dogs. J Am Vet Med Assoc 174:1083–1085, 1979

 

From the Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.

Address reprint requests to Bart Van Goethem, DVM, Spoorweglaan 38A, 9140 Temse, Belgium. E-mail: bart.vangoethem@tiscali.be.

Submitted April 2005; Accepted June 2005

© Copyright 2006 by The American College of Veterinary Surgeons

0161-3499/04

doi:10.1111/j.1532-950X.2006.00124.x

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Duration, complications, stress, and pain of open ovariohysterectomy versus a simple method of laparoscopic-assisted ovariohysterectomy in dogs

Chad M. Devitt, DVM, MS, DACVS; Ray E. Cox, DVM; Jim J. Hailey, DVM

 

Objective—To describe a simple method of laparoscopic-assisted ovariohysterectomy (LAOHE) and compare duration of surgery, complications, measures of surgical stress, and postoperative pain with open ovariohysterectomy (OHE) in dogs.

Design—Randomized, prospective clinical trial.

Animals—20 healthy sexually intact female dogs weighing > 10 kg (22 lb).

Procedures—Dogs were randomly allocated to receive conventional OHE or LAOHE. Intraoperative complications, anesthetic complications, total anesthesia time, and total surgery time were recorded. Serum cortisol and glucose concentrations, temperature, heart rate, and respiratory rate were measured preoperatively and 1, 2, 4, 6, 12, and 24 hours postoperatively. Pain scores were assigned by a nonblinded observer at 1, 2, 4, 6, 12, and 24 hours postoperatively. Duration of surgery, pain scores, objective measures of surgical stress, anesthetic complications, and surgical complications were compared between OHE and LAOHE.

Results—Age, weight, PCV, and duration of surgery did not differ between treatment groups. Nine of 10 dogs in the OHE group required additional pain medication on the basis of pain scores, whereas none of the dogs in the LAOHE group did. Blood glucose concentrations were significantly increased from preoperative concentrations in the OHE group at 1, 2, 4, and 6 hours postoperatively and at 1 hour postoperatively in the LAOHE group. Cortisol concentrations were significantly increased at 1 and 2 hours postoperatively in the OHE group.

Conclusions and Clinical Relevance—LAOHE caused less pain and surgical stress than OHE and may be more appropriate for an outpatient setting. (J Am Vet Med Assoc 2005;227:921–927)

 

Ovariohysterectomy (OHE) is a common surgical procedure performed in general practice for which the benefits and complications have been described extensively.¹⁻⁸ Laparoscopic methods of OHE are feasible in dogs.⁹⁻¹² However, laparoscopic procedures have not received widespread attention from veterinarians, in part because of the difficulty in mastering laparoscopic techniques, the complexity of the veterinary equipments, and the duration of laparoscopic procedures, compared with open procedures.

Reduced pain associated with laparoscopic OHE has been reported.¹⁰ However, more rigorous comparisons of laparoscopic versus open OHE have yet to establish a clear advantage.ᵃ Some would argue that the benefits of a laparoscopic procedure, compared with a mini-laparotomy as used for OHE, are negligible.¹²⁻¹⁵ Furthermore, prolonged duration of surgery makes laparoscopic procedures less attractive in the typical practice setting.¹⁰

Laparoscopic-assisted procedures maintain minimally invasive attributes of laparoscopic surgery while allowing complex procedures to be performed more efficiently by use of extracorporeal maneuvers. Laparoscopic-assisted procedures have minimal impact, similar to an entirely laparoscopic approach.¹⁶ Laparoscopic-assisted techniques in veterinary medicine such as laparoscopic-assisted gastropexy have reduced the complexity of a minimally invasive gastropexy.¹⁷ This procedure now is routinely used in many practice settings. Similarly, a simple technique for laparoscopic-assisted OHE (LAOHE) was developed. The technique is performed via 2 midline portals, with an operative laparoscope, bipolar cautery, and a specially designed table to permit rotation of the patient from dorsal recumbency to left or right lateral recumbency.

We hypothesized that LAOHE would cause less pain than conventional open OHE, whereas duration of surgery, anesthetic variables, and complications would be similar. The purpose of the study reported here was to compare the duration of surgery, duration of anesthesia, anesthetic complications, surgical complications, and signs of postoperative pain of LAOHE versus open OHE in dogs in a randomized, prospective clinical trial.

Materials and Methods

The institutional animal care and use committee of the Veterinary Referral Center of Colorado approved this protocol. Twenty healthy sexually intact female dogs that weighed > 10 kg (22 lb) and were scheduled for adoption through local animal shelters were randomly allocated to either OHE or LAOHE groups. Owner consent was obtained for dogs that were placed with adopting owners. Consent from the animal shelter director was obtained for all others that were not adopted at the time of the study. Physical evaluation and preoperative CBC and serum biochemical profile were performed and found to be within reference ranges in all dogs.

Twenty-four hours prior to surgery, a 16-gauge through-the-needle catheterᵇ was placed aseptically into the external jugular vein to facilitate and minimize stress associated with blood sample acquisition. If a jugular site was not available, a saphenous vein was used. Serum glucose and cortisol concentrations were measured at baseline after a 24-hour period of acclimation following catheter placement prior to premedication for anesthesia (preoperative) and 1, 2, 4, 6, 12, and 24 hours after extubation. A 10-mL sample of blood was aspirated from the catheter. Serum glucose concentration was measured with a glucometerᶜ immediately after sample acquisition and reported in milligrams per deciliter. Packed cell volume was measured in a standard fashion. A 5-mL aliquot of blood was dispensed into a serum separator tube, clot formation was allowed to occur, and the sample was immediately centrifuged. Following centrifugation, serum was harvested immediately, stored at –80o C in labeled Eppendorf tubes, and evaluated for cortisol concentration at the end of the study by a commercial laboratory via solid-phase radioimmunoassay.ᵈ

Anesthesia—Dogs were preanesthetized with glycopyrrolate (0.01 mg/kg [0.0045 mg/lb], SC), morphine (0.2 mg/kg [0.09 mg/lb], SC), and acepromazine (0.03 mg/kg [0.01 mg/lb], SC). General anesthesia was induced with diazepam (0.2 mg/kg, IV) and propofol (3 mg/kg [1.3 mg/lb], IV) and maintained with isoflurane via endotracheal intubation. Bupivicaine (2 mg/kg [0.9 mg/lb], SC) was infused into the surgical site (OHE) or divided between portal sites (LAOHE) prior to incision. Systolic, diastolic, and mean arterial pressures were measured via arterial catheterization of the dorsal pedal artery or the distal radial artery. Continuous ECG; systolic, diastolic, and mean arterial pressures; heart and respiratory rates; end-tidal (ET) CO2; ET isoflurane; and pulse oximetry SpO2 were monitored and recorded during the duration of the anesthesia. Mechanical ventilation was provided as deemed necessary during anesthesia (PETCO2 > 55 mm Hg).

Surgical procedures—All surgeries were performed by 1 surgeon (CMD). Dogs randomly allocated into the OHE group had the procedure performed as described,⁹ with minor modification of the incision size to encompass the middle third of the umbilicopubic distance, rather than the described half of the umbilicopubic distance, to more closely replicate OHEs performed in general practice. Dogs in the LAOHE group were placed in a surgical table (essentially a wooden-hinged V-trough) designed to facilitate rotation of the patient from dorsal recumbency to right or left lateral recumbency while maintaining an aseptic surgical field (Figure 1). While in dorsal recumbency, pneumoperitoneum was attained in a standard fashion (10 to 13 mm Hg) with CO2, a Verres needle, and a mechanical insufflator.ᵉ A 12-mm cannula positioned at the level of the umbilicus was used to insert an 11-mm operative laparoscope with a 6 X 114-mm operating channel (Figure 2).ᶠ Retraction of the spleen and intestines was facilitated by rotation of the patient to right lateral recumbency, which allowed vision of the abdominal viscera and identification of the left ovariouterine complex. The left ovary was grasped and brought to the body wall, which allowed percutaneous advancement of a transabdominal suspension suture (1.0 polydioxanone) with a CT-1 (large taper) needleᵍ to maintain exposure of the ovarian pedicle (Figure 3). With the lights diverted from the surgical field, transillumination of the region was evident. The needle was advanced through the body wall, becoming visible laparoscopically. The needle was directed through the ovariouterine complex, encircling the tissue, and directed out the abdominal wall; the suture was tied, effectively maintaining exposure of the ovarian vasculature.

In multiparous animals, additional transabdominal suspension sutures were placed as needed to retract the uterine horn and facilitate exposure of the ovarian pedicle. The suspensory ligament and ovarian vasculature were progressively cauterized and divided with a multifunction bipolar grasping forcepsh (Figure 4). The right ovarian pedicle was identified, exposure was maintained with a transabdominal suspension suture, and the pedicle was progressively cauterized and divided in a similar fashion. Retraction of the intestines and pancreas was facilitated by rotation of the patient to left lateral recumbency (Figure 1). After division of both ovarian pedicles, the patient was returned to dorsal recumbency. A 5- or 12-mm cannula was inserted via direct viewing at the caudal portion of the midline approximately 4 to 5 cm cranial to the pubis (caudal portal). Endosurgical grasping forceps were introduced into the caudal midline portal, and the right horn of the uterus and associated ovary were grasped (Figure 5). The transabdominal suspension suture was released, and the right ovary and associated uterine horn were exteriorized through the abdominal wall via the caudal portal (Figure 6). The caudal portal was enlarged as necessary to allow ease of exteriorization of the ovary. The left ovary and associated uterine horn were exteriorized in a similar fashion. The body of the uterus was ligated, transfixed, and divided in a standard fashion. The ligated uterine stump was reintroduced into the peritoneal cavity through the caudal portal and inspected with the laparoscope for hemostasis and entrapment of regional tissues. The portal sites were closed in 2 layers with monofilament absorbable suture and nylon. Surgical time of OHE was recorded from the initiation of the skin incision to the final skin suture. Surgical time of LAOHE was recorded from the initiation of the pneumoperitoneum to the final skin suture. Total anesthesia time for both groups was from time of induction and intubation to time the vaporizer was set at 0% at the end of the procedure. After surgery, recovery occurred in an isolated environment and blood samples were obtained at 1, 2, 4, 6, 12, and 24 hours after extubation. Morphine was administered after surgery (0.2 mg/kg, SC) to all dogs prior to extubation. Pain scores were assigned on the basis of increase from baseline of heart rate, respiratory rate, mean arterial pressure, behavior, and response to wound palpation at 1, 2, 4, 6, 12, and 24 hours after extubation by 1 of 2 nonblinded technicians (Table 1).¹⁸ Patients with scores > 6 were given additional morphine (0.2 mg/kg, SC).

Statistical analysis—All statistical analyses were performed by use of statistical software.i Mean and SD values were calculated. Age, weight, surgical time, and total anesthesia time were compared between treatment groups with an unpaired t test. Two-way ANOVA for repeated measures was used to compare the effects of treatment group and time on pain scores. The proportion of patients that required mechanical ventilation during anesthesia and additional morphine was compared between treatment groups with the Fisher exact test, and relative risk was calculated. One-way ANOVA for repeated measures was used to compare differences within treatment groups for blood glucose and cortisol concentrations obtained at various times. If a significant effect was detected, the Dunnett multiple comparison test was used to compare preoperative values with values obtained at each subsequent measurement point. For all comparisons, significance was set at α = 0.05.

[table id=12 /]

Results

Mean ± SD age was 1.5 ± 0.93 years and 1.45 ± 0.78 years for the OHE and LAOHE groups, respectively (P = 0.444). Mean ± SD weight was 22.1 ± 5.0 kg (48.6 ± 11.0 lb) and 22.0 ± 5.6 kg (48.4 ± 12.3 lb) for the LAOHE and OHE groups, respectively (P = 0.488). Mean ± SD duration of surgery for LAOHE was 20.8 ± 4.0 minutes, and mean duration of surgery for OHE was 18.6 ± 3.9 minutes (P = 0.133). Mean ± SD duration of anesthesia for LAOHE was 46.3 ± 10.0 minutes, and mean duration of anesthesia for OHE was 44.0 ± 9.6 minutes (P = 0.303).

One dog in the OHE group required treatment for hypotension (mean arterial pressure, < 60 mm Hg) with volume expansion (10 mL/kg [4.5 mL/lb], IV bolus) and ephedrine (0.1 mg/kg [0.05 mg/lb], IV). Six dogs (3 in the OHE group and 3 in the LAOHE group) required mechanical ventilation to maintain ETCO2 < 55 mm Hg. During anesthesia, subjective assessment revealed inadequate depth of anesthesia during insufflation of the abdominal cavity with CO2 in 3 of 10 patients in the LAOHE group. Similarly, signs of inadequate depth of anesthesia were detected during digital breakdown of the ovarian pedicle in 9 of 10 patients in the OHE group. Signs of inadequate depth of anesthesia were not detected in any patients during bipolar cautery division of the pedicles.

Surgical complications were not encountered in any dogs in the LAOHE group. In 1 dog in the OHE group, the ovarian pedicle was torn during digital breakdown of the suspensory ligament, which required extension of the incision to locate the bleeding vessel and provide hemostasis. Packed cell volume was not significantly different between or within groups at any time point (P = 0.856).

Pain scores were higher at all points for the OHE group, compared with the LAOHE group (P = 0.001; Figure 7). Nine of 10 dogs in the OHE group required additional pain medication on the basis of pain scores, whereas none in the LAOHE group did (P = 0.001; relative risk, 10.0 [95% confidence interval, 1.6 to 64.2]). Measurements of surgical stress were tabulated (Table 2). Blood glucose concentrations were significantly increased from preoperative concentrations in the OHE group at 1, 2, 4, and 6 hours and in the LAOHE group at 1 hour. Cortisol concentrations were significantly increased from preoperative concentrations at 1 and 2 hours in the OHE group. Cortisol concentrations were not significantly increased in the LAOHE group.

[table id=13 /]

Discussion

Laparoscopic-assisted ovariohysterectomy as described provided rapid exposure of the ovary and uterus by changing position from dorsal recumbency to lateral recumbency with the use of a specially designed table. Although the table was not necessary to change position, it was useful in maintaining an aseptic surgical field by facilitating rotation from right to left lateral recumbency. Head-down or Trendelenburg positioning was not used. Previously described⁹⁻¹² laparoscopic neutering techniques use 3 or more ports to allow passage of endosurgical graspers or retractors to locate and maintain exposure of the ovariouterine complex during ligation and transection of the ovarian pedicle. Those techniques are inherently time-consuming and can be frustrating if surgical assistance is provided by someone inexperienced in laparoscopic surgery. The use of transabdominal suspension sutures to maintain exposure of the ovarian pedicle eliminated the need for additional portals and a surgical assistant to maintain exposure.²⁰ Additionally, exteriorizing of the uterine horns through the caudal portal and performing extracorporeal ligation and division of the uterine body further simplify the procedure.

Surgical complications were not encountered in the LAOHE group; however, this technique is not without potential complications. Improper use of cautery and transabdominal suspension sutures can bring the structures being transected too close to the abdominal wall, increasing the likelihood of collateral thermal injury, particularly in the hands of an inexperienced laparoscopic surgeon. Strict adherence to proper technique and use of bipolar cautery are important to prevent collateral injury. For example, after grasping the tissue and prior to application of the cautery mode, the tissue must be retracted away from the abdominal wall and other adjacent structures to prevent collateral thermal injury. The complication of subcutaneous migration of CO2 did not occur in the LAOHE group. This was likely because of the method used to create the portal (ie, the closed method), the minimal distension pressure (13 mm Hg), and the short duration of the procedure. Use of an open method to create a portal can increase the risk of this complication if the skin incision is smaller than the body wall incision.19 Additionally, increased distention pressures approaching 15 mm Hg can increase risk. In another veterinary study,⁹ subcutaneous accumulation of CO2 has been reported. In our clinical experience, this is not associated with substantial discomfort and it typically resolves spontaneously without treatment. Careful monitoring and cessation of the laparoscopic procedure are required if subcutaneous emphysema leads to pneumomediastinum or pneumothorax.

The durations of LAOHE and OHE (20.8 vs 18.6 minutes, respectively) were not significantly different. Our study was designed to detect > 15% difference in duration of the procedures with a power of 80%. This difference was chosen as a conservative clinically relevant difference. In a recent comparison10 of laparoscopic OHE versus OHE, the duration of conventional OHE was found to be significantly shorter than laparoscopic OHE (69 vs 129 minutes, respectively). The authors of that study suggest that with experience, consistently performing a laparoscopic OHE in < 1 hour is realistic. Laparoscopic neutering is routinely performed in Europe. In a recent report11 of a large number of dogs that received laparoscopic ovariectomy, the duration of surgery and complications with use of monopolar or bipolar cautery were compared. Duration of surgery was reduced by the use of bipolar cautery to a mean surgical time of 41 minutes. The duration of our method of LAOHE compared favorably with other reported methods of laparoscopic neutering.

Techniques of laparoscopic neutering performed with a harmonic scalpel, vascular clips, or endosurgical suturing methods to secure the ovarian pedicle and the uterine body have been described.⁹,¹⁰ Although an effective and efficient endosurgical tool, a harmonic scalpel is expensive to acquire and use. Bipolar electrocoagulation is a safe, less expensive alternative to the harmonic scalpel. Its use has been reported¹¹,²¹ in horses and dogs for cauterization and transection of the ovarian pedicle. The bipolar forceps used in the dogs of the present study were designed to have multiple functions including grasping, cauterization, and transection of vascular tissue. As such, cumbersome instrument exchanges can be avoided, which further simplifies complex maneuvers and minimizes the number of ports used for the procedure.

Evaluation of postoperative signs of pain is inherently subjective. Postoperative composite pain scores were used to provide a simple method to determine the need for additional pain medication. Mean composite pain scores were significantly lower at all points postoperatively for the LAOHE group, compared with the OHE group. Nine of 10 patients in the OHE group required additional morphine, whereas none of the dogs in the LAOHE group required additional morphine. Relative risk of requiring additional postoperatively administered pain medication in the OHE group was 10 times greater than in the LAOHE group. Unfortunately, no method of pain evaluation is perfect. We used a scoring system used most recently by Walsh et al¹⁸ and used in pediatric human studies²² and veterinary studies.²³ The system is based on increases of easily measured physiologic variables (heart rate, respiratory rate, and mean arterial pressure) and categories of behavioral responses. At each time point, physiologic variables are measured without patient interaction and compared with baseline values. Behavioral responses are categoric and leave little opportunity for introduction of subjective biases. Baseline data were obtained in a standard fashion in all dogs prior to randomization into groups. The advantage of this system is that it is easily applied by technical staff with minimal subjective analysis and training. One disadvantage of this system is the difficulty of applying this method of pain evaluation in clinical practice in other than elective procedures. Other systems, such as a visual analogue scale, would have been more difficult to use to obtain information for the purposes of our study. Visual analogue scale scores are based on the evaluators’ past experiences and perceptions of an animal’s pain. A visual analogue scale would be difficult to apply in a busy private practice setting and would require additional training.

Intuitively, the smaller incision required for the LAOHE would seem to account for differences in pain with laparoscopic or laparoscopic-assisted procedures, compared with open procedures. Pain that occurs after an open procedure is also attributed to desiccation of exposed viscera and disruption of the peritoneal surface.²⁴ Less pain associated with LAOHE, compared with OHE, is also attributed to the relatively atraumatic nature of bipolar cauterization and transection of the ovarian pedicle, compared with digital disruption of the suspensory ligament. Digital disruption of the suspensory ligament extends to the peritoneal attachment and exposes retroperitoneal space. During this procedure, 9 of 10 patients in the OHE group had signs of pain. In contrast, similar signs of pain were not detected during bipolar cauterization and division.

Blood glucose and serum cortisol concentrations are useful measures of surgical stress. Blood glucose remained significantly increased for 6 hours after extubation in the OHE group and only for 1 hour in the LAOHE group. Additionally, significant increases from baseline of cortisol concentrations occurred only in the OHE group. Laparoscopic and thoracoscopic procedures or other effective measures of pain control reduce surgical stress.¹⁸,²⁵⁻²⁷ Other causes of increased glucose and cortisol concentrations include the stress of hospitalization. Our patient population consisted of shelter dogs acclimated to kennel confinement. To minimize variations associated with hospitalization, all patients were hospitalized 24 hours prior to entering the study.

It is well accepted that preemptive analgesia is important to limit the overall degree of pain a patient has after a given procedure.²⁸⁻³⁰ Despite the advances in recognition and management of pain that have occurred in veterinary medicine, inadequate management of pain is commonplace.³¹,³² Many dogs ovariohysterectomized in general practice are managed as outpatients, with minimal additional pain relief. Results of the present study illustrated that minimally invasive surgery can be viewed as a maneuver to reduce or preempt pain after surgery. One may consider minimally invasive methods more appropriate in an outpatient setting typical of general practice.

The benefits of veterinary laparoscopy or laparoscopic-assisted procedures have been validated by an enormous amount of clinical experience with laparoscopic surgery in humans. Yet, minimally invasive procedures have been slow to gain widespread use in small animal surgery. Laparoscopic-assisted ovariohysterectomy as described is less complex than laparoscopic OHE because of the use of 2 ports, minimal instrumentation, and conventional extracorporeal techniques. Results of our study provided evidence for reduced postoperative pain, whereas duration of surgery and anesthetic and surgical complications were similar.

Since completion of this study, the first author has modified the LAOHE technique to use 1 portal. A pneumoperitoneum is established, a 12-mm cannula is placed on midline at the level of the fourth mammary gland, and the operative laparoscope is inserted into the abdominal cavity. Retraction of the spleen and intestines is facilitated by rotation of the patient to right or left lateral recumbency, which allows the surgeon to see the abdominal viscera and identify the left or right ovariouterine complex, respectively. The ovaries are grasped and brought to the body wall, which allows percutaneous advancement of a transabdominal suspension suture; the suspensory ligament and ovarian vasculature are progressively cauterized and divided. After division of both ovarian pedicles, the patient is returned to dorsal recumbency. The proximal portion of the uterus is grasped with the multifunctional grasping forceps approximately 0.5 cm caudal to the ovary, the transabdominal suspension sutures are released, and the secured uterine horn is retracted into the 12-mm cannula. The cannula, laparoscope, bipolar graspers, and proximal portion of the uterus are retracted out of the portal for exteriorization of the uterine horn and associated ovary. The opposite uterine horn is exteriorized by a hand-over-hand maneuver, exposing the junction of the uterine body and uterine horn and subsequently the ovary. The uterine body is transfixed, ligated, and divided in an extracorporeal fashion. The single portal site is closed in 2 layers with absorbable monofilament and nylon suture. This modification allows further reduction in the impact of the surgical procedure by elimination of extra entries into the peritoneal cavity and reduces the number of endosurgical instruments required.

a. Remedios A, Ferguson J, Walker D, et al. Laparoscopic versus open ovariohysterectomy in dogs: a comparision of postoperative pain and morbidity (abstr). Vet Surg 1997;26:425.

b. Venocath-16, Abbott Ireland Ltd, Sligo, Ireland.

c. Accu-Chek Advantage, Roche Diagnostic Corp, Indianapolis, Ind.

d. Coat-A-Count, Antech Diagnostics, Farmingdale, NY.

e. Surgassist, Biovision Technologies, Golden, Colo.

f. Operating laparoscope (11 mm), Biovision Technologies, Golden, Colo.

g. PDS, Ethicon, Sommerville, NJ.

h. Endoblade, Biovision Technologies, Golden, Colo.

i. GraphPad Prism, version 4.00 for Macintosh, GraphPad Software, San Diego, Calif.

References

1. Pollari FL, Bonnett BN, Bamsey SC, et al. Postoperative complications of elective surgeries in dogs and cats determined by examining electronic and paper medical records. J Am Vet Med Assoc 1996;208:1882–1886.

2. Wallace MS. The ovarian remnant syndrome in the bitch and queen. Vet Clin North Am Small Anim Pract 1991;21:501–507.

3. Kyles AE, Douglass JP, Rottman JB. Pyelonephritis following inadvertent excision of the ureter during ovariohysterectomy in a bitch. Vet Rec 1996;139:471–472.

4. Coolman BR, Marretta SM, Dudley MB, et al. Partial colonic obstruction following ovariohysterectomy: a report of three cases. J Am Anim Hosp Assoc 1999;35:169–172.

5. Bradley KJ, Billet JP, Barr FJ. Dysuria resulting from an encapsulated haematoma in a recently spayed bitch. J Small Anim Pract 2000;41:465–467.

6. Merlo M, Lamb CR. Radiographic and ultrasonographic features of retained surgical sponge in eight dogs. Vet Radiol Ultrasound 2000;41:279–283.

7. Stocklin-Gautschi NM, Hassig M, Reichler IM, et al. The relationship of urinary incontinence to early spaying in bitches. J Reprod Fertil Suppl 2001;57:233–236.

8. Fingland R. Ovariohysterectomy. In: Bojrab M, ed. Current techniques in small animal surgery. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 1998;489–493.

9. Austin B, Lanz OI, Hamilton SM, et al. Laparoscopic ovariohysterectomy in nine dogs. J Am Anim Hosp Assoc 2003;39:391–396.

10. Davidson EB, Moll HD, Payton ME. Comparison of laparoscopic ovariohysterectomy and ovariohysterectomy in dogs. Vet Surg 2004;33:62–69.

11. Van Goethem BE, Rosenveldt KW, Kirpensteijn J. Monopolar versus bipolar electrocoagulation in canine laparoscopic ovariectomy: a nonrandomized, prospective, clinical trial. Vet Surg 2003;32:464–470.

12. Bailey J, Freeman L. Endosurgery. In: Bojrab M, ed. Current techniques in small animal surgery. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 1998;729–746.

13. Syrakos T, Antonitsis P, Zacharakis E, et al. Small-incision (mini-laparotomy) versus laparoscopic cholecystectomy: a retrospective study in a university hospital. Langenbecks Arch Surg 2004; 389:172–177.

14. Ros A, Gustafsson L, Krook H, et al. Laparoscopic cholecystectomy versus mini-laparotomy cholecystectomy: a prospective, randomized, single-blind study. Ann Surg 2001;234:741–749.

15. Alponat A, Cubukcu A, Gonullu N, et al. Is minisite cholecystectomy less traumatic? Prospective randomized study comparing minisite and conventional laparoscopic cholecystectomies. World J Surg 2002;26:1437–1440.

16. Bernstein MA, Dawson JW, Reissman P, et al. Is complete laparoscopic colectomy superior to laparoscopic assisted colectomy? Am Surg 1996;62:507–511.

17. Rawlings CA, Mahaffey MB, Bement S, et al. Prospective evaluation of laparoscopic-assisted gastropexy in dogs susceptible to gastric dilatation. J Am Vet Med Assoc 2002;221:1576–1581.

18. Walsh P, Remedios A, Ferguson J, et al. Thoracoscopic versus open partial pericardectomy in dogs: comparision of postoperative pain and morbidity. Vet Surg 1999;28:472–479.

19. Wright D, Serpell M, Baxter J, et al. Effect of extraperitoneal carbon dioxide insufflation on intraoperative blood gas and hemodynamic changes. Surg Endosc 1995;9:1169–1172.

20. Rosin D, Kuriansky J, Rosenthal RJ, et al. Laparoscopic transabdominal suspension sutures. Surg Endosc 2001;15:761–763.

21. Rodgerson DH, Belknap JK, Wilson DA. Laparoscopic ovariectomy using sequential electrocoagulation and sharp transection of the equine mesovarium. Vet Surg 2001;30:572–579.

22. Hannallah R, Broadman L, Belman A, et al. Comparison of caudal and ilioinguinal/iliohypogastric nerve blocks for control of post-orchiopexy pain in pediatric ambulatory surgery. Anesthesiology 1987;66:832–834.

23. Conzemius MG, Brockman DJ, King LG, et al. Analgesia in dogs after intercostal thoracotomy: a clinical trial comparing intravenous buprenorphine and interpleural bupivacaine. Vet Surg 1994; 23:291–298.

24. Watson RW, Redmond HP, McCarthy J, et al. Exposure of the peritoneal cavity to air regulates early inflammatory responses to surgery in a murine model. Br J Surg 1995;82:1060–1065.

25. Naitoh T, Garcia-Ruiz A, Vladisavljevic A, et al. Gastrointestinal transit and stress response after laparoscopic vs conventional distal pancreatectomy in the canine model. Surg Endosc 2002; 16:1627–1630.

26. Marcovich R, Williams AL, Seifman BD, et al. A canine model to assess the biochemical stress response to laparoscopic and open surgery. J Endourol 2001;15:1005–1008.

27. Fox SM, Mellor DJ, Firth EC, et al. Changes in plasma cortisol concentrations before, during and after analgesia, anaesthesia and anaesthesia plus ovariohysterectomy in bitches. Res Vet Sci 1994; 57:110–118.

28. Bailey J, Pablo L. Anesthetic and physiologic considerations for veterinary endosurgery. In: Freeman L, ed. Veterinary endosurgery. St Louis: CV Mosby Co, 1999;24–43.

29. Lascelles BD, Cripps PJ, Jones A, et al. Post-operative central hypersensitivity and pain: the pre-emptive value of pethidine for ovariohysterectomy. Pain 1997;73:461–471.

30. Lascelles BD, Cripps PJ, Jones A, et al. Efficacy and kinetics of carprofen, administered preoperatively or postoperatively, for the prevention of pain in dogs undergoing ovariohysterectomy. Vet Surg 1998;27:568–582.

31. Hellyer PW. Treatment of pain in dogs and cats. J Am Vet Med Assoc 2002;221:212–215.

32. Wagner AE, Hellyer PW. Survey of anesthesia techniques and concerns in private veterinary practice. J Am Vet Med Assoc 2000; 217:1652–1657.

 

From the Veterinary Surgical Services, Veterinary Referral Center of Colorado, 3550 S Jason St, Englewood, CO 80110 (Devitt); the Deer Creek Animal Hospital, 10148 W Chatfield Ave, Littleton, CO 80127 (Cox); and My Pet’s Place, 9111 S Santa Fe Dr, Littleton, CO 80125 (Hailey).

Supported by Biovision Corporation, Golden, Colo.

Address correspondence to Dr. Devitt.

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MINIMALLY INVASIVE SURGERY: WHY IT’S NOT GOING AWAY AND WHAT IT MEANS TO YOU

J. Brad Case, DVM, MS, DACVS College of Veterinary Medicine University of Florida, Gainesville, FL

 

OVERVIEW

Minimally Invasive Surgery (MIS) is defined as any surgery that results in less tissue trauma or pain when compared with a traditional “larger” approach. Minimally invasive surgery is sometimes referred to as “keyhole surgery” to reflect the small incision(s) that are used.

Because MIS is relative, the philosophy can be applied to many, if not all, surgical procedures so long as there is a comparison in which one technique induces more trauma than the other. For example, open reduction and rigid plate fixation for appendicular fractures is now being performed routinely in a minimally invasive fashion in certain cases. The difference between a traditional approach and a minimally invasive approach has to do with the length of the required skin incision and the degree of manipulation and disruption of the fracture segments. This minimally invasive approach to fracture repair is referred to as minimally invasive plate osteosynthesis (MIPO) and often requires intraoperative imaging (i.e., fluoroscopy) to guide the procedure. Similar procedures are being performed in veterinary neurologic surgery including spinal fracture reduction and fixation, intervertebral disk fenestration, and hemilaminectomy. These procedures are performed via small incisions under the guidance of intraoperative fluoroscopy and/or endoscopic cameras.

Veterinary laparoscopy is a form of MIS and is further defined as surgery of the peritoneal cavity using a video-telescope and small instruments, which are manipulated from the outside of the abdomen. Similarly, thoracoscopy or video-assisted thoracic surgery (VATS) is MIS within the thoracic cavity. Both laparoscopy and VATS require significant working space within the abdomen or chest, respectively, and require insufflation with carbon dioxide gas (laparoscopy) or pneumothorax (VATS) in most cases. These procedures are minimally invasive in that they require only small (typically 5‒20 mm) incisions to complete the procedure, which is in contrast to a traditional, much larger laparotomy or thoracotomy.

The list of laparoscopic and VATS procedures being performed in veterinary surgery is extensive and is continuously evolving as surgeons gain more experience and as technology facilitates development of newer procedures. For example, the introduction of bipolar energy-based vessel/tissue sealing and dividing technology has facilitated an explosion of new applications in both laparoscopic and VATS surgery, including ovariectomy, ovariohysterectomy, cryptorchiectomy, splenectomy, ureteronephrectomy, adrenalectomy, cholecystectomy, pericardectomy, peripheral lung lobectomy, and cranial mediastinal mass resection. Precision manufacturing of surgical implants has also facilitated the advancement of endoscopic and intravascular minimally invasive procedures: for example, tracheal stent placement for tracheal collapse, percutaneous coil embolization of intrahepatic portosystemic shunts, bland embolization and chemoembolization of visceral tumors, glue and coil embolization of vascular malformations and palliative stenting for malignant obstructions, to name a few. The combination of advances in imaging technology and high precision implant manufacturing has led to the development of a new discipline in both human and veterinary surgery, namely interventional radiology. Now, procedures that once required an open thorax and/or abdomen and risky vascular surgery are performed completely via an introducer through a peripheral artery or vein.

This shift to minimal surgical approaches has and will continue to occur in veterinary surgery just as it has in human medicine. For example, over the past 15 to 20 years, laparoscopic cholecystectomy has become the gold standard for the most common abdominal procedure performed in humans. Now days, if a medical doctor offers open cholecystectomy for elective cases, it is recommended that the patient get a second opinion, to put it kindly.

Although there are few differences between humans and veterinary patients, perhaps the most important similarity is the perception of physical and emotional distress and pain. There should be little doubt that reducing the degree of tissue injury in humans and animals will result in less pain and improve the quality of recovery for the patient. Laparoscopic cholecystectomy in humans has reduced the average hospital stay from 5 to 7 days to less than 24 hours and has resulted in significantly fewer complications including incisional failure and blood loss. Perhaps the most analogous procedural evolution in veterinary surgery is ovariectomy and the development of laparoscopic ovariectomy. Numerous studies have demonstrated less postoperative pain with few or no complications in dogs undergoing laparoscopic ovariectomy, which has made it the procedure of choice for many veterinarians. The same relationship exists for laparoscopic gastropexy (Figure 1) compared with open gastropexy (Figure 2). Because laparoscopy currently has the most applicability to general practice, the remainder of this article will discuss MIS as it relates to laparoscopy, specifically.

LAPAROSCOPIC INDICATIONS

At the current time, numerous indications for laparoscopy exist in veterinary medicine and surgery. The astute clinician would be wise to become comfortable with the ideas and principles of MIS as to provide refined surgical options to their clients. Minimally invasive surgery is not just for specialists. Rather, the most common procedures could be and are readily adaptable to general practice assuming the practitioner is dedicated to developing the skills necessary to become successful. Common indications for laparoscopy in general practice include ovariectomy (OVE), ovariohysterectomy (OHE), cryptorchidectomy, gastropexy, liver biopsy, pancreatic biopsy, lymph node biopsy, and intestinal biopsy. These procedures are being performed safely and effectively in many practices and the demand for them is increasing rapidly. Although there are geographic and demographic limitations this trend will continue into the future and will likely have significant economic consequences in veterinary practice.

LAPAROSCOPIC CONTRAINDICATIONS

A significant learning curve exists with performing laparoscopy. Well-developed psychomotor skills are a prerequisite but so is appropriate training. Many laboratories and courses are offered each year and should be attended if considering performing laparoscopy in practice. Thus, the first contraindication to MIS is inexperience or lack of comfort with procedures. Inexperienced or untrained staff is another contraindication, which is remedied by adequate training. Inadequate instrumentation is also a contraindication. When starting out, all laparoscopic procedures should be performed on an elective basis only. This will help to insure adequate planning and preparation so as to increase the chances of a successful outcome. Advanced procedures and procedures that require exploration of the abdomen are also not appropriate for the beginning endoscopist; traditional surgical approaches should be performed in these cases. One of the major limitations with traditional laparoscopy is the inability to feel or palpate organs. Instead, the laparoscopist relies on his or her ability to see and/or palpate with a probe the tissues of interest, which limits assess-ability.

LAPAROSCOPY EQUIPMENT

A variety of instruments are available and designed to be used with veterinary laparoscopy. A list and brief description of the more common instruments is included here:

• Camera: The camera is attached to the telescope and light source and is used to capture and transmit imaging from inside the abdomen to a video screen. There are two types of cameras used in veterinary endoscopy, 1-chip and 3-chip. In general, the 1-chip cameras have fewer pixels per unit area and reproduce color to a lesser degree than do 3-chip cameras. That being said, 1-chip cameras are significantly cheaper and produce images almost as bright and colorful as 3-chip cameras.
• Telescope: The telescope is a long rigid instrument, which attaches to the camera and is used to explore the peritoneal cavity. Typical telescopes are either 5 or 10 mm in diameter and either 0 or 30 degrees oblique. The most common scope in veterinary surgery is a 5 mm 0 degree.
• Light source: The light source most commonly used in veterinary surgery is xenon and is powered up to 300 Watts. The larger the wattage, the brighter the image.
• Insufflator: The insufflator is an automatic pump, which controls the flow rate and intra-abdominal pressure during the laparoscopic procedures. Carbon dioxide gas is used and is sourced from a high-pressure tank. Air is not used as it may result in air embolism.
• Cannula: A cannula or port is the instrument used to obtain and maintain access to the peritoneum. The cannula serves as a sleeve for the insertion and removal of the telescope and instruments.
• Trocar: Trocar refers to the combination of an obturator and cannula together.
• Obturator: The obturator is the inner component of the trocar and is either sharp or blunt. The obturator is removed once the trocar has been positioned correctly in the abdomen.
• Veress needle: A Veress needle is a small-gauge needle, which has an outer sharp edge and a spring-loaded, blunt inner obturator. It is used to penetrate the peritoneal cavity for insufflation prior to insertion of laparoscopic trocars.
• Surgical instruments: A variety of laparoscopic surgical instruments should be available:
  • 5-mm blunt probe o 5-mm Babcock forceps
  • 5-mm Clamshell biopsy forceps
  • 5-mm Punch biopsy forceps
  • 5-mm Kelly dissecting forceps
  • 5-mm Metzenbaum scissors
• Bipolar Energy Devices: Either a LigaSure or Harmonic Scalpel should be included in a laparoscopy set. These are specialized instruments used for combined vessel/ tissue sealing and division. They are more effective at hemostasis and surgical efficiency compared with monopolar and earlier bipolar systems (e.g., Patton HotBlade). Both the LigaSure and Harmonic Scalpel systems come with a variety of hand pieces, which makes them incredibly versatile. The LigaSure is effective in sealing vessels <7 mm while the Harmonic Scalpel seals vessels <5 mm.

STERILIZATION

A number of different sterilization modalities are available. Typically, the scopes, cameras, light cables, and energy-based sealing devices are gas sterilized (e.g., ethylene oxide) as this improves instrument life. However, steam sterilizers can also be used for steel instruments. Most laparoscopic surgery instruments are composed of steel and can be sterilized in traditional steam sterilizers. Cold sterilization using 2% glutaraldehyde solution is also described for laparoscopic telescopes. The camera head can either be sterilized overnight in a gas sterilizer or can be reused by use of sterile sleeve covers. Because laparoscopic instruments tend to be made of small fragile components, careful cleaning practices are required to prevent damage and incomplete disinfection/sterilization.

CONCLUSION

In summary, MIS is an ever-evolving discipline that relates to most facets of surgery. Further, minimally invasive approaches are being requested with greater and greater frequency by animal caregivers just as they are by patients in human surgery. After all, human patients are frequently our clients and they often expect the same level of care for their pets. Minimally invasive veterinary surgery include many benefits such as less tissue trauma, less pain and quicker recovery are extremely desirable to our clients and the astute veterinarian would be wise to become familiar with these concepts and procedures so as to be able to offer the highest standard of care to his or her clients and patients. Many routine abdominal procedures can be and are currently being performed readily in general practice provided that the practitioner has invested in the appropriate equipment and training, and is committed to successfully performing routine procedures with regularity.