Ovariohysterectomy

• Excision of ovaries and uterus - normally performed simultaneously.

Elective

• Prevention of estrus.
• Control of breeding by sterilization.
• Prophylaxis of mammary neoplasia Mammary gland: neoplasia if performed early - preferably before the first heat.
• Reduced prevalence of acquired inguinal hernias.

Ovarian disease

• Neoplasia Ovary: neoplasia.
• Abnormal estral cycles Prolonged pro-estrus and estrus.

Uterine disease - non-gravid

• Neoplasia Uterus: neoplasia.
• Pyometra/cystic endometrial hyperplasia (CEH) Pyometra.
• Acute metritis Acute metritis.
• Hemometrium.
• Subinvolution of placental sites.

Uterine disease - gravid

• Prolapse Uterine prolapse.
• Torsion.
• Rupture.
• Fetal death/mummification/maceration/dystocia Dystocia.
• Abortion Abortion / stillbirth.

Vaginal disease

• Hyperplasia/prolapse Vagina: prolapse.
• Benign vaginal tumors Vaginal neoplasia.

Systemic disorders

• Management of diabetes mellitus Diabetes mellitus.
• Management of epilepsy Epilepsy: idiopathic.
• Management of demodicosis Skin: demodectic mange.

Advantages

• Relatively safe procedure. Significantly reduces incidence of mammary gland tumors (the most common kind of cancer in dogs) if performed early.

Disadvantages

• May predispose to urinary incontinence and obesity.

• Ovariectomy, open or laparoscopic Laparoscopy: ovariectomy, is widely practiced in Europe and may be an acceptable alternative.

Preparation

• 20 min.

Procedure

• 20-45 min.

Criteria for choosing test

Timing - before first estrus (usually 6-12 months old); or prepubertal OHE is widely accepted and considered a safe alternative

• Decreased technical, surgical, difficulty and bleeding risk, but special anesthesia and care requirements post-operatively.
• Maximum health benefit in prevention of mammary neoplasia.
• Increased risk of hypoplastic genitalia (which may predispose to perivulvar dermatitis) and urinary incontinence Urinary incontinence, especially in predisposed breeds (significance unproven).

Timing - mature bitch (elective)

• When progesterone level is no more than 2 ng/ml (baseline) Progesterone assay, to avoid sudden drop of progesterone and consequent release of prolactin leading to phantom pregnancy. This occurs:
  • Either 2 or preferably 4 months after estrus (anestrus).
  • Or a minimum of 9 weeks post-partum.

Risk assessment

Increased risk

• During estrus.
• Geriatric.
• Obesity.
• During pregnancy.
• With concurrent diabetes mellitus Diabetes mellitus.
• Animals with family history of bleeding disorders.
  Routine surgical procedures should be avoided within 3 weeks of modified live vaccination; if possible, transient thrombocytopenia may result.

Pre-operative evaluation - normal young (<5 years)

• PCV Hematology: packed cell volume and plasma protein Blood biochemistry: total protein; urine specific gravity Urinalysis: specific gravity.

Pre-operative evaluation - older bitch

• Complete cell blood counts Hematology: complete blood count (CBC).
• Renal and liver function Renal function assessment Liver Function assessment.

Pre-operative evaluation - animals with previous/family history of bleeding disorders

• Screen using buccal mucosal bleeding time Buccal mucosal bleeding time.
• Platelet count Hematology: platelet count.
• Prothrombin time Hematology: prothrombin time.
• Activated partial prothrombin time Hematology: activated partial thromboplastin time.
• Von Willebrand factor measurement Von Willebrand's factor.

Systemic disease

• Pyometra Pyometra : full investigation, including urinalysis and abdominal ultrasonography.

Minimum equipment

• Standard laparotomy pack Surgical instruments.

Ideal equipment

• Abdominal retractor .

• Fast animal for 4-8 h prior to anesthesia (depending on age and breed) to prevent reflux esophagitis and nausea/vomiting during induction and recovery.

Approach

• Midline approach usual.
  Adequate laparotomy incision (from umbilicus to pubis) decreases risk of ovarian and uterine bleeding by facilitating recognition, exposure and ligation of individual blood vessels. However, usually the incision starts just caudal to the umbilicus and extends halfway between umbilicus and pubis.
• Flank approach rarely used.

• General anesthesia General anesthesia: overview.

Step 1 - Incision

• Same as standard laparotomy Laparotomy: midline .
  Ovarian tissues are better visualized by extending incision up to or even beyond the umbilicus.
• Rarely is it necessary to extend incision caudally beyond halfway between umbilicus and pubis.

Step 1 - Locate left uterine horn and ovary, rupture of the ovarian suspensory ligament (SL) and fenestrate left broad ligament

Locate left horn and uterine ovary

• Retract descending colon to locate left ovary 2-3 cm caudal to the left kidney .
• Alternatively, find cervix/uterine bifurcation dorsal to the bladder.

Rupture of the ovarian suspensory ligament

• This releases ovary and extends pedicle.
• Identify suspensory ligament as the taut fibrous band at the ventral (ie the closest to the incision) margin of the ovarian pedicle and tear or stretch it by gentle retraction in a caudal medial direction, as cranially as possible (close to the kidney).

• Alternatively, it is possible to make a small incision with scissors in the suspensory ligament.
• Include suspensory ligament with ovarian pedicle ligatures if vascularity noted.
  Blood vessel within suspensory ligament may bleed in the mature bitch, pyometra or pregnancy.

Fenestrate left broad ligament

• Create fenestration in broad ligament immediately behind the ovarian vessels. Do not dissect through fat - find a clear area of broad ligament.
  Take care not to tear ovarian artery - risk of severe hemorrhage.
• Create ovarian pedicle .

Step 2 - Ligate ovarian artery and vein, resect all ovarian tissue

Ligate ovarian artery and vein

• Use 3 clamp technique to crush ovarian pedicle, all positioned below ovary, only closing it 1 click of the ratchet, to prevent tissue tearing.
• Place a first encircling ligature dorsal (below) the most dorsal clamp, and a second ligature around the most dorsal clamp (one tail of the suture above the clamp and one tail below). Close the ratchet completely, then remove the clamp as the ligature is tightened, so that the ligature sits in the crush of the clamp.
• Ligatures can be tied with a surgeon's knot , a Miller's knot or a transfixing ligature depending on the size of the pedicle and the preference of the surgeon Suture patterns.
• Maintaining appropriate tension on the first throw of a surgical knot around a vessel is crucial because the throw can be loosened by the tissue pressure when the suture ends are released to create the second locking throw.
• When using a transfixing ligature the needle has to be backed through the pedicle to avoid penetrating the vessels. Make sure to ligate around the vessels first, and then encircle the entire pedicle .
• For a Miller's knot, pass the suture under the pedicle, back in front of it and under the pedicle one more time. This creates a small loop of suture around the pedicle. The needleholder is passed through the loop and used to grasp the free end of the suture on the far side and pass it through the loop. A knot is placed and tightened, then completed by placing 3 or 4 more square knot throws .
• Ligate the ovarian blood vessels using absorbable suture material  preferably polyglactin 910 or monofilament (polyglyconate, polydioxanone, glycomer) in size from 0 to 3/0 depending on the size of the pedicle Suture materials.
• If using chromic catgut ensure adequate ligature tightness, as this suture is hydrophilic and will swell up and loosen with vessel oozing. Furthermore, its enzymatic degradation increases the inflammatory response.
• Avoid including any other tissue in the ligatures, as this may cause adhesions and/or slipping of the tissue through the ligature.
• A recent article (Watts, 2018) advocates the use of bipolar electrosurgery for hemostasis during open ovariectomy of bitches and queens.

Resect all ovarian tissue

• Transect or tear ovarian pedicle between the second and the third clamp .
• Grasp ovarian pedicle with thumb forceps and relax it toward the abdominal cavity.
• Release clamp slowly checking for hemorrhage; if none is seen, the pedicle is released.

Step 3 - Rupture broad ligament

• Break down/transect broad ligament lateral to the uterine vessels.
• Ligation with an encircling ligature is necessary in most cases in adult bitches.

The reduced blood pressure of general anesthesia may camouflage vessels which may hemorrhage post-operatively.

• Find right ovary by following the ipsilateral uterine horn to the bifurcation, then following contralateral horn cranially.
• Repeat above procedure for right ovary .

Step 4 - Ligate uterine arteries at level of cervix

• Idenitfy uterine bifurcation and cervix .
• There is no need to clamp the uterus, which can be friable and tear if clamped.
• Place two ligatures just cranial to the cervix, the kind of suture depending on the uterine body size (two encircling ligatures if small, two stick-tie ligatures if large/with prominent vessels).
• For a stick-tie ligature, pass the needle around the right or left uterine vessel and tie a square knot; the ligature then encircles the entire uterine body and is secured with a surgeon's knot.

  It is not advisable to enter the uterine lumen with the suture, as this may cause uterine vessels erosion with post operative bleeding.

Step 5 - Resect uterus at cervix

• Resect uterus 0.5 cm cranial to the most cranial ligature after having applied a clamp across the uterine body just cranial to the proposed transection sute.
• Hold edge of stump with forceps, observe for evidence of bleeding before releasing into abdominal cavity.

Step 1 - Check for hemorrhage

• Check for hemorrhage from ovarian blood vessels.
• Recheck uterine stump for bleeding by elevating the bladder.

Step 2 - Closure of laparotomy

• Same as standard laparotomy Laparotomy: midline.

Analgesia

• Use of NSAIDs Analgesia: NSAID immediately pre-operatively and continue for 3-4 days after surgery.
• Ensure adequate values of blood pressure intra-operatively (alternatively, can administer NSAIDs in the immediate postoperative period).
• Supplement with narcotic analgesics as necessary for first 24 hours.

Antimicrobial therapy

• None indicated for prophylaxis; if uterine infection or devitalization is present, use antibiotics according to culture and sensitivity results.
• Infection risk is increased for anesthetic time longer than one hour.

Wound Protection

• Use Elizabethan collar if dog is observed licking the incision.

Special precautions

• Restrict exercise until skin sutures are removed.

Potential complications

• Observe for evidence of intra-abdominal hemorrhage.
• Anesthetic recovery complications.

• Same as standard laparotomy Laparotomy: midline.

• Good when electively performed in healthy animal.

Obesity

Immature genitalia, vulvitis and immature behavior

• If spayed too young (?unproven folklore).

Exacerbation of urinary incontinence

• Due to urethral sphincter mechanism incompetence Urinary incontinence: urethral sphincter mechanism incompetence (USMI).

Hypogonadal syndrome

• Decreased activity, energy conservation, weight gain and altered feeding pattern.

Laparotomy failures

• Same as standard laparotomy Laparotomy: midline (dehiscence/hernias, seroma Seroma).

Recurrent estrus

• Failure to remove all ovarian tissue (usually right side).

Skin sinuses and granulomas

• Flank or per vagina.
• Due to use of braided non-absorbable suture material for pedicle/stump ligation, that becomes contaminated and serves as a nidus of infection.

Trapped ureter

• Inclusion of one/both ureters in uterine ligature, causing hydronephrosis or vagino-ureteral fistula with severe incontinence.

Adhesions

• Same as standard laparotomy Laparotomy: midline (very unlikely but could involve bladder, omentum, small intestine).
• Adhesions, occasionally encircling, beween distal colon and uterine stump.
• Uterine stump pyometra with retained ovarian tissue, or exogenous progestational compound administration.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Watts J (2018) The use of bipolar electrosurgical forceps for haemostasis in open surgical ovariectomy of bitches and queens and castration of dogs. JSAP 59 (8), 465-473 PubMed.
• Sundburg C R, Belanger J M, Bannasch D L et al (2016) Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study. BMC Vet Res 12 (1), 278 PubMed. 
• Leitch B J, Bray J P, Kim N J (2012) Pedicle ligation in ovariohysterectomy: an in vitro study of ligation techniques. JSAP 53 (10), 592-598 PubMed.
• Ball R L, Birchard S J, May L R et al (2010) Ovarian remnant syndrome in dogs and cats: 21 cases (2000–2007). JAVMA 236 (5), 548-553 PubMed.
• Miller D M (1995) Ovarian remnant syndrome in dogs and cats: 46 cases (1988-1992). J Vet Diagn Invest 7 (4), 572-574 PubMed.
• Wallace M S (1991) The ovarian remnant syndrome in the bitch and queen. Vet Clin North Am Small Anim Pract 21 (3), 501-507 PubMed.

Other sources of information

• Fingland R B, Waldron D R (2014) Ovariohysterectomy.  In: Current techniques in Small Animal Surgery. 5th edn. Ed M J Bojrab. Baltimore, Williams & Wilkins
• Fransson B A (2012) Ovaries and uterus. In: Veterinary Surgery Small Animal. 1st edn. Tobias K M & Johnston S A (eds). Philadelphia, Elsevier Saunders, pp 5657-5737.
• Tobias K M (2010) Ovariohysterectomy. In: Manual of Small Animal Soft Tissue Surgery. Hoboken, Wiley-Blackwell, pp 241-254.
• Hedlund C S (2007) Surgery of the Reproductive and Genital Systems. In: Small Animal Surgery. 3rd edn. Fossum T W (ed) St. Louis, Mosby Elsevier, pp 702-774.