Indications for Ovariectomy/Ovariohysterectomy

Elective ovariectomy (OVE) or ovariohysterectomy (OHE) of dogs and cats is one of the most commonly performed surgical procedures in small animal practice.¹ In addition to reducing pet overpopulation, elective neuter also prevents spread of disease and animal suffering.² Because laparoscopic surgery is associated with reduced tissue trauma and pain, laparoscopic OVE and/or OHE have become popular in veterinary patients.^3,4

Pyometra is defined as septic, suppurative inflammation of the primed uterus, which occurs under the influence of progesterone. Progesterone levels increase during diestrus. Increasing progesterone levels cause: 1) reduction in uterine motility, 2) increase in glandular secretions and 3) constriction of the cervix. These effects create and ideal environment for growth of bacteria should the region become inoculated. Inoculation of the vagina and uterus occurs from skin, perineal and rectal microflora.

Pyometra affects approximately 25% of intact female dogs by 10 years of age.⁵ While medical management can be attempted in dogs intended for breeding, recurrence is reported.⁶ Surgical management with ovariohysterectomy, is the treatment of choice.⁷

Ovariohysterectomy is typically performed via an open ventral midline celiotomy but minimally invasive techniques are becoming standard practice and both laparoscopic and laparoscopic-assisted techniques are described.^3,4,8-10 Four-port,⁸ three-port⁹ and single-port¹⁰ laparoscopic-assisted OHE techniques for dogs with pyometra have also recently been described.

Pyometra

Dogs with pyometra deserve special consideration prior to undergoing laparoscopic OHE. Preliminarily dogs should be systemically stable and able to tolerate anesthesia and pneumoperitoneum. Intravenous fluid resuscitation is often required due to prior inadequate voluntary intake and polyuria which results from interference of antidiuretic hormone at the distal tubule and collecting ducts. Additionally, broad- spectrum antimicrobial therapy should be initiated and continued perioperatively. Escherichia coli is the causative agent in the majority of dogs with pyometra, thus a potentiated penicillin or second-generation cephalosporin are good antimicrobial options.

Diagnostic evaluation should include a complete blood count, serum chemistry, urinalysis and abdominal ultrasound or radiography. Two recent studies have demonstrated feasibility of laparoscopic OHE in dogs between 2 and 40 kgs with uterine diameters less than 4 cm.^9,10 Dogs with uterine diameters greater than 4 cm, especially if smaller (<10 kg), should be approached cautiously if considering a laparoscopic approach as feasibility in larger diameter uteri has not been demonstrated.

Positioning and Port Location

A number of different port locations for ovariectomy and ovariohysterectomy have been described in the veterinary literature.^3,4,9,10-12 Although a four-port technique has been described for OHE, the most common techniques utilized for both OHE and OVE are three-, two- and single-port. In a recent study, a two-port laparoscopic OVE technique was associated with less postoperative pain but equivalent surgery time compared to a three-port technique; and equivalent postoperative pain and a shorter surgery time when compared to a single-port technique.¹¹ Thus, a two-port technique appears to balance the benefits of surgical efficiency and minimization of tissue injury.¹¹

All patients are positioned in dorsal recumbency and clipped from xiphoid to pubis and dorsally past the level of the 13th rib. A wide clip is necessary to accommodate placement of the trans-abdominal suspension suture or weighted hook. The abdomen is aseptically prepared as for traditional laparotomy.

A skin incision no larger than the size of the intended cannula is made using a surgical blade. The subcutaneous tissues are dissected down to the linea.

To circumvent placing a Veress needle, the Hasson technique can also be used. The Hasson technique is performed by creating a mini-laparotomy. A 5.5-mm cannula with blunt trocar is preferred. The size of the skin and linea incision is no larger than the intended camera port (usually 5 mm). Stay sutures are placed on both sides of the linea incision to allow traction during insertion of the blunt trocar. The trocar is inserted at an approximate 30-degree angle, towards the right caudal abdomen, to avoid iatrogenic injury to the spleen. Once the cannula is inserted, the obturator is removed and the CO₂ tubing attached. The abdomen is insufflated to a pressure of 10 mm Hg. All subsequent instrument trocars are placed under direct laparoscopic visualization to avoid intra-abdominal visceral injury. A two-port laparoscopic OVE/OHE technique will be described here.

Laparoscopic Assisted OHE

Laparoscopic-assisted OHE is performed similarly to laparoscopic OVE with the exception that the caudal cannula be placed in a more caudal location (over the uterine body) and the uterine body is ligated extracorporeally via the caudal port site. Additionally, because the uterine body is ligated extracorporeally, the author prefers to use an 11.5-mm cannula in the caudal location for larger (>10 kg) dogs. The general location for the caudal cannula should be approximately 1/3 of the distance between the umbilicus and the pubis. The cranial cannula can be placed 2–3 cm cranial to the umbilicus as for laparoscopic OVE. Once the cannulas have been placed, the dog is repositioned into lateral-oblique recumbency and both ovarian pedicles ligated and divided as described for laparoscopic OVE. Dissection of the broad ligament to approximately midway between the ovarian pedicle and uterine body is all that is typically required prior to elevation from the caudal cannula site. Once both ovarian pedicles have been divided and the broad ligament dissected, the dog is positioned in dorsal recumbency and the left proper ligament is grasped with the Babcock forceps and brought to the base of the caudal cannula. If needed, the caudal port incision is lengthened directly over the cannula while maintaining the grasp of the proper ligament. The cannula is then removed over the Babcock forceps and the ovary and uterine horn extracted from the abdomen. If further dissection of the broad ligament is needed, this can be done extracorporeally with the bipolar devise. The contralateral uterine horn and ovary is easily traced and extracted similarly to the left. Once the uterine body has been well exposed the uterine body can be ligated in standard fashion. The uterine stump is inspected for bleeding and returned to the abdominal cavity. The port sites are closed according to the the guidelines described for laparoscopic OVE.

Complications

Complications from laparoscopic ovariectomy and ovariohysterectomy are rare but can include: hemorrhage, subcutaneous emphysema, visceral organ injury (e.g., spleen), inability to complete the procedure requiring conversion to laparotomy, pain, seroma formation, and rarely infection.

References

1.  Greenfield CL, Johnson AL, Schaeffer DJ. Frequency of use of various procedures, skills, and areas of knowledge among veterinarians in private small animal exclusive or predominant practice and proficiency expected of new veterinary school graduates. J Am Vet Med Assoc. 2004;224(11):1780–1787.

2.  Detora M, McCarthy RJ. Ovariohysterectomy versus ovariectomy for elective sterilization of female dogs and cats: is removal of the uterus necessary? J Am Vet Med Assoc. 2011;239(11):1409–1412.

3.  Hancock RB, Lanz OI, 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;34:273–282.

4.  Devitt CM, Cox RE, Hailey JJ. Duration, complications, stress and pain of open ovariohysterectomy versus a simple method of laparoscopic-assisted ovariohysterectomy in dogs. J Am Vet Med Assoc. 2005;227:921–927.

5.  Egenvall A, Hagman R, Bonnett BN, Hedhammar A, Olson P, Lagerstedt. Breed risk of pyometra in insured dogs in Sweden. J Vet Intern Med. 2001;15:530–538.

6.  Gobello C, Castex G, Kilma L, Rodriguez R, Corrada Y. A study of two protocols combining aglepristone and cloprostenol to treat open cervix pyometra in the bitch. Theriogenology. 2003;60:901–908.

7.  Fransson BA. Ovaries and uterus. In: Tobias KM, Johnston SA, eds. Veterinary Surgery: Small Animal. St Louis, MO: Elsevier; 2012:1871–1890.

8.  Minami S, Okamoto Y, Eguchi H, Kato K. Successful laparoscopy assisted ovariohysterectomy in two dogs with pyometra. J Vet Med Sci. 1997;59:845–847.

9.  Adamovich-Rippe KN, Mayhew PD, Runge JJ, et al. Evaluation of laparoscopic-assisted ovariohysterectomy for treatment of canine pyometra. Vet Surg. 2013;42:572–578.

10. Wallace M, Case JB, Singh A, et al. Single incision, laparoscopic-assisted ovariohysterectomy for mucometra and pyometra in dogs. Vet Surg. 2015;44:66–70.

11. Case JB, Marvel SJ, Boscan P, Monnet EL. Surgical time and severity of postoperative pain in dogs undergoing laparoscopic ovariectomy with one, two, or three instrument cannulas. J Am Vet Med Assoc. 2011;2:203–208.

12. Dupré G, Forbianco V, Skalicky M, Gultiken N, Ay SS, Findik M. Laparoscoppic ovariectomy in dogs: comparison between single portal and two-portal access. Vet Surg. 2009;7:818–824.