Contributors: David Godfrey, Rob Lofstedt, Rosa Ragni

 Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading


  • Excision of ovaries and uterus - normally performed simultaneously.



  • Prevention of estrus.
  • Control of breeding by sterilization.
  • Prophylaxis of mammary neoplasia  Mammary gland: neoplasia (Overley et al, 2005).

Ovarian disease

Uterine disease - nongravid

Uterine disease - gravid

Vaginal disease

Mammary gland disease


Hair regrowth after a flank approach may be darker - this may be unacceptable to some owners - a ventral midline approach should be used as an alternative in these instances.

Alternative Techniques

Time Required


  • 15 min.


  • 15-20 min.

Decision Taking

Criteria for choosing test

Always inform owner that OHE is major surgery.

Timing - before first estrus

  • Usually 6-12 months old although spaying from about 8 weeks old has become standard in some practices.
  • Decreased surgical risk.
  • Maximum health benefit in prevention of mammary neoplasia.
  • Increased risk of hypoplastic genitalia causing urinary incontinence (significance unknown) Urinary incontinence.

Timing - mature female

  • The queen has numerous follicle waves in spring and summer. She can be ovariectomized at any time, even during a peak of follicle activity without significant risk.
  • Post partum, after the kittens have been weaned.

Risk assessment

Increased risk

  • Geriatric.
  • Obesity Obesity.
  • During pregnancy.
  • Diabetes.
  • Animals with family history of bleeding disorders.
  • Within 3 weeks of vaccination.

Preoperative evaluation - normal young (<5 years)

Preoperative evaluation - older female

Preoperative evaluation - animals with previous/family history of bleeding disorders

Systemic disease


Materials Required

Minimum equipment


Site Preparation


  • Flank approach usual in UK Laparotomy: flank Ovariohysterectomy 01: prepared flank  Ovariohysterectomy 02: draped surgical site  Ovariohysterectomy 03: towel clips .
  • Impossible to recover a slipped ovarian pedicle from this approach.
  • Midline is standard in North America Laparotomy: midline.
    Hair regrowth after a flank approach may be darker - this may be unacceptable to some owners - a ventral midline approach should be used as an alternative in these instances, especially in cats with points.
  • Midline approach where increased exposure required or as above.





Step 1 - Incision

Midline approach

  • Same as standard laparotomy Laparotomy: midline
  • Incise the middle third of the distance between umbilicus to pubis on ventral midline.

Flank approach

  • Usually performed from left flank (right lateral recumbency) Ovariohysterectomy 04: skin incision  Ovariohysterectomy 05: abdominal fat  Ovariohysterectomy 06: sublumbar fat.
  • Hind limbs are extended caudally and tied.
  • Landmarks = cranial edge of ilium wing and greater trochanter.
  • The starting point of the incision is the third vertex of an equilateral triangle with the two above landmarks as the other vertices.
  • Incise skin, subcutaneous fat, and external aponeurosis in a dorsoventral direction. Alternatively, the incision can be oblique from dorsocranial to ventrocaudal.
  • Avoid the deep circumflex iliac vessels, located ventrally to the cranial iliac tip.
  • Identify the internal and transverse abdominal oblique muscles and enter them with a grid approach, incising along the muscle fibers.
  • Incise the peritoneum.

Core Procedure

Step 1 - Locate left uterine horn and ovary

Midline approach

Either Locate left ovary just caudal to the left kidney.
Or  Find cervix/uterine bifurcation to the bladder and follow it cranially to the left ovary.

Flank approach

  • Identify the retroperitoneal fat encountered entering the abdominal cavity and roll it updwards using two dressing forceps: the left uterine horn is found underneath.
  • Follow the left uterine horn cranially to the left ovary Ovariohysterectomy 01  Ovariohysterectomy 02.

Step 2 - Rupture the ovarian suspensory ligament (to give better visualization of ovarian vessels)

  • Retract ovary and gently stretch mesovarian ligament with finger/thumb Ovariohysterectomy 08: traction applied to uterine horn .
    Blood vessel within suspensory ligament may bleed in the mature female, pyometra or pregnancy.

Step 3 - Fenestrate left mesometrium

  • Create fenestration in mesometrium (the broad ligament immediately behind the ovarian vessels) Ovariohysterectomy 09: fenestration .
    Take care not to tear ovarian artery - risk of severe hemorrhage.
  • Create ovarian pedicle containing the uterine branch of the ovarian artery as well as the ovarian artery itself.
    The queen and bitch do not have a middle uterine artery and the cranial blood supply to the uterus is ligated automatically when the ovarian pedicle is ligated.

Step 4 - Ligate ovarian artery and vein

  • Place two clamps below the ovary, only closing it 1 click of the ratchet, to prevent tissue tearing Ovariohysterectomy 10: clamped ovarian pedicle .
  • Ligate the ovarian blood vessels with a surgeon's knot  dorsal (below) the clamps, using 3/0-2/0 absorbable suture material such as polyglactin 910 or monofilament (polyglyconate, polydioxanine, glycomer Suture materials: absorbableOvariohysterectomy 11: ligation  Ovariohysterectomy 12: ligated pedicle .
  • Avoid including any other tissue in the ligatures, as this may cause adhesions and/or slipping of the tissue through the ligature.

Step 5 - Resect all ovarian tissue

  • Close the clamp ratchets completely then transect the tissue between them.
  • It is also possible to tear the tissue (at the same location) by a rotating/twisting motion; this will increase vasospasm and decrease risk of hemorrhage.
  • Release clamp slowly and release pedicle in the abdominal cavity checking for hemorrhage.
  • A recent article (Watts, 2018) advocates the use of bipolar electrocautery for hemostasis during open ovariectomy of bitches and queens.
  • All ovarian tissue must be removed, this is easier in the queen than the bitch as the ovary of the queen is not covered with an ovarian bursa as it is in the bitch.
  • It is possible to leave ovarian blood vessel ligatures long to allow easy checking of vessels before abdominal surgery.

Rupture mesometrium

  • Use blunt dissection to separate the uterine horn from the mesometrium (broad ligament).
  • Ligate any blood vessels which may bleed/ooze (rare).
    The reduced blood pressure of general anesthesia may camouflage vessels which may hemorrhage postoperatively.

Ligate and resect right ovary

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

Resect uterus at cervix

  • Identify uterine bifurcation and cervix.
  • There is no need to clamp the uterus, which can be friable and tear if clamped.
  • Place ligature on uterine body, just cranial to cervix, including the caudal vascular supply to the uterus Ovariohysterectomy 22: tie uterine ligatures  Ovariohysterectomy 23: uterus ligated  Ovariohysterectomy 24: uterus ligated 2 . In case of a pregnant/large uterus it is preferable to place two ligatures, at least one of which is a stick-tie ligature.
  • 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.
  • 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 site.
  • Hold edge of stump with forceps, observe for evidence of bleeding before releasing into abdominal cavity  Ovariohysterectomy 03 .


Step 1 - Check for hemorrhage

  • Check for hemorrhage from ovarian blood vessels (can use long ends of ligatures to aid visualization, then cut ligature ends to standard length).

Step 2 - Closure of laparotomy



Special precautions


  • 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 Analgesia: opioid.

Antimicrobial therapy

  • None indicated for prophylaxis; if uterine infection of 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 cat is observed licking the incision.

Special precautions

  • Restrict exercise until skin sutures are removed.




  • Good when electively performed in healthy animal.

Reasons for Treatment Failure

Exacerbation of urinary incontinence

  • Due to urethral sphincter mechanism incompetence.

Hypogonadal syndrome

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

Laparotomy failures

Recurrent estrus

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

Fistulous tracts

  • Flank or per vagina.
  • Due to use of non-absorbable suture material.

Trapped ureter

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

Pyometra, abscessation/granuloma

  • Due to failure to remove uterine tissue to level of cervix.


  • Same as standard laparotomy Laparotomy: midline (may involve bladder, omentum, small intestine).
  • Adhesions, occasionally encircling, between distal colon and uterine stump.

Further Reading


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, 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 et al (2012) Pedicle ligation in ovariohysterectomy: an in vitro study of ligation techniques. JSAP 53 (10), 592-598 PubMed.
  • Little S (2011) Feline Reproduction: problems and clinical challenges. J Fel Med Surg 13 (7), 508-515 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.
  • Burrow R, Wawra E, Pinchbeck G et al (2006) Prospective evaluation of postoperative pain in cats undergoing ovariohysterectomy by a midline or flank approach. Vet Rec 158 (19), 657-660 PubMed.
  • Overley B, Shofer F S, Goldschmidt M H et al (2005) Association between ovariohysterectomy and feline mammary carcinoma. J Vet Intern Med 19 (4), 560-563 VetMedResource.
  • Al-Gizawiy M M & Rudé P E (2004) Comparison of preoperative carprofen and postoperative butorphanol as postsurgical analgesics in cats undergoing ovariohysterectomy. Vet Anaesth Analg 31 (3), 164-174 PubMed.
  • McGrath H, Hardie R J, Davis E (2004) Lateral flank approach for ovariohysterectomy in small animals. Comp Contin Educ Pract Vet 26 (12), 922-30 VetMedResource.
  • Slingsby L S & Waterman-Earson A E (2002) Comparison between meloxicam and carprofen for postoperative analgesia after feline ovariohysterectomy. JSAP 43 (7), 286-289 PubMed.
  • Coolman B R, Marretta S M, Dudley M B et al (1999) Partial colonic obstruction following ovariohysterectomy: a report of three cases. JAAHA 35 (2), 169-172 PubMed.
  • Kustritz M V (1999) Early spay-neuter in the dog and cat. Vet Clin North Am Small Anim Pract 29 (4), 935-943 PubMed.
  • Slingsby L S, Lane E C, Mears E R et al (1998) Post-operative pain after ovariohysterectomy in the cat: a comparison of two anaesthetic regimens. Vet Rec 143 (21), 589-590 PubMed.
  • Slingsby L S, Waterman-Pearson A E (1998) Comparison of pethidine, buprenorphine and ketoprofen for post-operative analgesia after ovariohysterectomy in the cat. Vet Rec 143 (7), 185-189 VetMedResource.
  • Howe L M (1997) Short-term results and complications of prepubertal gonadectomy in cats and dogs. JAVMA 211 (1), 57-62 PubMed.
  • Pollari F L, Bonnet B N, Bamsey S C et al (1996) Post-operative complications of elective surgeries in dogs and cats determined by examining electronic and paper medical records. JAVMA 208 (11), 1882-1886 VetMedResource.
  • Smith M C, Davies N L (1996) Obstipation following ovariohysterectomy in a cat. Vet Rec 138 (7), 163 PubMed.
  • Miller D M (1995) Ovarian remnant syndrome in dogs and cats: 46 cases (1988-1992). J Vet Diagn Invest (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.
  • Langley-Hobbs S J (2014) Female genital tract. In: Feline Soft Tissue and General Surgery. Langley-Hobbs S J, Demetriou J L, Ladlow J F (eds). Philadelphia, Elsevier Saunders. pp 458-463.
  • Fransson A B (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.