Ovary: ovariectomy - laparotomy approach in Horses (Equis) | Vetlexicon
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Ovary: ovariectomy – laparotomy approach

ISSN 2398-2977


  • Ovaries are removed from mares for two reasons: pathologic changes or management practices.
  • A number of different approaches and techniques are available to the surgeon.
  • Ovariectomy is associated with a higher frequency of peri-operative complications than some other elective surgical procedures.


  • Removal of ovaries bilaterally from mares not intended for breeding, ie behavior-related management reasons or to use the mare as a 'jump mare'.
  • Removal of ovarian neoplasia Ovary: neoplasia - overview.
  • Removal of ovarian hematoma.
  • Removal of ovarian teratoma.


  • Treatment of choice for removal of ovarian neoplasia.


  • High frequency of peri-operative complications, some of which can be life-threatening.
  • Technically difficult to exteriorize ovary and ligate it.

Alternative techniques

  • Management of female horses not required for breeding may involve hormonal therapy or different management/handling practices. Ovariectomy should be the last resort.
  • No viable alternative for neoplasia of the ovary except euthanasia Euthanasia.
  • There are 3 recognized approaches:

Time required


  • General anesthetic induction and maintenance: 20 min.
  • Aseptic preparation: 10-15 min.


  • Unilateral: 60 min.
  • Bilateral: 75 min.

Decision taking

Criteria for choosing test

  • See Ovary: neoplasia - overview.
  • Management of behavioral problems are preferably treated by changes in practices or hormonal therapy which are easily administered, eg Altrenogest Altrenogest (Regumate), transient and carry little risk.
  • Choice of approach:
    • Ovariectomy by colpotomy Ovary: colpotomy is a viable approach for elective ovariectomy in normal mare.
    • Via laparotomy Abdomen: laparotomy is preferred for ovarian tumors especially large ones, and can be used for elective bilateral ovariectomy.
    • Laparoscopy Abdomen: laparoscopy:
      • Limitation in the size of ovary to be removed.
      • Provides a useful alternative to laparotomy where facilities are unavailable for general anesthetic administration or the patient is a general anesthetic risk.
      • Minimally invasive with much less problems with wound healing, less post-operative care and complications, faster return to normal management and exercise.


Materials required

Minimum equipment

  • Standard surgical kit.

Ideal equipment

  • Either a TA90 stapler or emasculator.

Minimum consumables

  • Doubled 1 or 2 synthetic absorbable suture material, eg polyglactin 910 or polydioxanone Surgery: suture materials - overview.
  • 2 and 2/0 or 0 synthetic absorbable suture material, eg polyglactin 910 or polydioxanone Surgery: suture materials - types.
  • Skin staples or 0 or 2/0 synthetic non-absorbable suture material, eg polypropylene.
  • Stent bandage.



Dietary preparation

  • Withold food for at least 24 h (usually 48 h) to decrease gut contents bulk, but maintain hydration.

Site preparation

  • Surgical approaches include:
    • Colpotomy or vaginal (dorsal vaginal wall) approach.
    • Standing or recumbent flank (paralumbar fossa) approach.
    • Ventral midline or paramedian approach.
    • Oblique paramedian approach.
  • Selection is based on mare temperament, size of ovary, unilateral or bilateral removal, personal preferences, economics.

Other preparation


  • General anesthesia Anesthesia: general - overview with horse in dorsal recumbency for the ventral midline or paramedian approaches and kin lateral recumbency with the ovary to be removed uppermost for the recumbent flank approach.
  • The flank approach can be performed with the mare standing for good-tempered mares, in which case it is necessary to have the mare sedated, restrained in stocks and with her tail wrapped and held clear of the surgical site .



Step 1 - Incision

  • A flank approach is rarely used except occasionally in a very short ovarian pedicle: grid incision in ovaries <10 cm diameter; muscle transection if larger Abdomen: surgical approaches.
  • Ventral midline incision beginning just cranial to the mammary gland, proceeding 25-35 cm cranial Abdomen: laparotomy. Useful in elective bilateral ovariectomy and large tumors.
  • Oblique paramedian approach: 20 cm incision on a line from the base of the mammary gland toward the cranial aspect of the fold of the flank, starting 10 cm cranial to the udder. Incise the external sheath of the rectum abdominis and separate the muscle bluntly in the same direction as the skin incision. Bluntly perforate the internal sheath and peritoneum.

Step 2 - Identify and anesthetize ovarian pedicle

Core procedure

Step 1 - Ovariectomy

  • Gently lift affected ovary/ovaries towards laparotomy incision.

Ovarian exposure can vary enormously - pressing the laparotomy edges downwards with the flat of the hand may help, particularly if the horse has been neuromuscular blocked.

Exposure and manipulation of the ovary, especially if enlarged, can be assisted by using stay sutures of umbilical tape or large diameter suture material, or by aspirating fluid from the cystic cavities in the ovary.

  • Achieve hemostasis:
    Either By placing doubled (2 absorbable suture material) overlapping transfixion ligatures around the pedicle - alternately as partial transection of the pedicle proceeds using either scissors or an emasculator.

The ligatures should be tied while the tissues are under minimal tension.

Or Use a staple gun, eg TA90 (Ethicon).

  • Blood supply to pathological ovary may require extensive ligation.

Step 3 - Check for hemostasis 

  • Evaluate transected stump for hemostasis.

Step 4 - Bilateral procedure

  • If the other ovary is to be removed, repeat the procedure via the same (ventral midline) incision.


Step 1 - Wound closure

  • Close the abdomen routinely using doubled 2 absorbable suture material.
  • The oblique paramedian incision is closed by suturing the rectus abdominies muscle and external sheath with 2 absorbable suture material.
  • Close the subcutaneous layer using 2/0 or 0 absorbable suture material.
  • Close the skin using 2/0 or 0 non-absorbable suture material or skin staples.
  • A stent bandage can be applied if preferred.


Immediate Aftercare


  • Observe closely for first 12-24 h to detect signs of abdominal pain or intra-abdominal hemorrhage.


  • Post-operative pain is common peri- and post-operative (3-5 days), especially if considerable tension has been placed on the pedicle during transection. NSAIDs will decrease pain and swelling (ventral midline laparotomy).

Antimicrobial therapy

Other medication

Special precautions

  • Exercise should be restricted: stable rest plus walking in-hand for 2-4 weeks, followed by turn out in a small paddock only until c 60-90 days post surgery.

Potential complications

  • Excessive swelling, scarring and dehiscence of flank incisions.

Long term Aftercare

Follow up

  • Remove laparotomy skin sutures at 14 days.



Reasons for treatment failure

  • Failure to remove all ovarian tissue.


  • Depends upon primary reason for surgery.
  • Guarded for behavioral reasons: although normal estrus cycles are prevented, this may not alleviate the abnormal behavior.
  • Guarded for ovarian granulosa theca cell tumors Ovary: neoplasia - granulosa / theca cell.
  • Unilateral resection: mares return to estrus in mean of 8.5 months.
  • Once the normal cycle has started, fertility appears to be unaffected. Most must go through winter anestrum following tumor removal before normal cycle resumes.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Melgaard D T, Korsgaard T S, Thoefner M S, Petersen M R & Pedersen H G (2020) Moody mares - is ovariectomy a solution? Animals (Basel) 10 (7), 1210 PubMed
  • Pinna A E, Okada C T C, Ferreira C S C et al (2019) Double ovarian tumour in the mare: case report. Reprod Domest Anim 54 (6), 912-916 PubMed.
  • Kelmer G, Raz T, Berlin D, Steinman A & Tatz A J (2013) Standing open-flank approach for removal of enlarged pathologic ovaries in mares. Vet Rec 172 (76), 687 PubMed.
  • Alldredge J G & Hendrickson D A (2004) Use of high-power ultrasonic shears for laparoscopic ovariectomy in mares. JAVMA 225 (10), 1579-1580 PubMed.
  • Boure L, Marcoux M & Laverty S (1997) Paralumbar fossa laparoscopic ovariectomy in horses with use of Endoloop ligatures. Vet Surg 26 (6), 478-483 PubMed.
  • Gottschalk R D & Van den Berg S S (1997) Standing laparoscopically-aided ovariectomy in mares. J S Afr Vet Assoc 68 (3), 102-104 PubMed.
  • Hendrickson D A & Wilson D G (1996) Instrumentation and techniques for laparoscopic and thoracoscopic surgery in the horse. Vet Clin North Am Equine Pract 12 (2), 235-259 PubMed.
  • Ragle C A, Southwood L L, Hopper S A & Buote P L (1996) Laparoscopic ovariectomy in two horses with granulosa cell tumors. JAVMA 209 (6), 1121-1124 PubMed.
  • Ragle C A & Schneider R K (1995) Ventral abdominal approach for laparoscopic ovariectomy in horses. Vet Surg 24 (6), 492-497 PubMed.
  • Doran R, Allen D & Gordon B (1988) Use of stapling instruments to aid in the removal of ovarian tumors in mares. Equine Vet J 20 (1), 37-40 PubMed.
  • Nickels F A (1988) Complications of castration and ovariectomy. Vet Clin North Am Equine Pract (3), 515-523 PubMed.
  • Slone D E Jr (1988) Ovariectomy, ovariohysterectomy, and cesarean section in mares. Vet Clin North Am Equine Pract (3), 145-459 PubMed.
  • Moll H D, Slone D E, Juzmiak J S & Garrett P D (1987) Diagonal paramedian approach for removal of ovarian tumors in mares. Vet Surg 16 (6), 456-458 PubMed.

Other sources of information

  • Rodgerson D H & Loesch D W (2011) Ovariectomy. In: Equine Reproduction. 2nd edn. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D D. Blackwell Publishing Ltd, USA. pp 2564-2573.