Caesarean Section - Horse
Introduction
Caesarean section can be the best method of delivery for various types of dystocia in the mare, especially in cases where the foetus cannot be easily repositioned (transverse presentation), or where the foetus is grossly oversized relative to the mare's birth canal.
Congenital deformities such as schistosomus reflexus or arthrogryposis may also be an indication for caesarean section.
It may also be the safest method of delivery for dead foals, where foetotomy is difficult, or in cases of prepubic tendon rupture.
Caesarean section should not be considered as a last resort and should be carried out promptly, preferably within an hour of the onset of stage 2, because placental separation will be occurring at a significant rate.
Anaesthesia and Surgical Preparation
Foetal depression should be minimised during the anaesthetic.
The sites commonly used for caesarean section include:
- Ventral midline: which requires general anaesthesia and is a common surgical site
- Paramedian: can be useful if the midline has previous laparotomy incisions
- Low left flank: with the mare standing, but there is limited exposure and access
If the ventral midline approach is chosen, the mare is placed in dorsal recumbency and is clipped and prepared for aseptic surgery in a routine manner.
Fluid therapy should be given.
Surgical Technique
Through the ventral midline incision, the uterus is located and an incision site over a limb is chosen.
The area is exteriorised as much as possible to avoid contamination of the peritoneal cavity. The uterus is incised and the foal removed. The incision should be large enough to allow removal of the foal without tearing of the uterine wall.
The allantochorion should be left inside the uterus unless it has already separated or will lift off easily.
Haemostasis is ensured by retracting the allantochorion and placing a continuous suture around the entire margin of the uterine incision. This is necessary because the equine endometrium is only loosely attached to the myometrium, and there is little natural haemostasis for the large subendometrial veins.
The uterus is closed with a double inverting layer of sutures and the abdomen is closed routinely.
If the uterus has ruptured or contents have leaked into the abdomen, copious lavage with warm physiologic solutions is indicated.
Penicillin and gentamycin can be instilled in the final wash as a special precaution.
Post-Operative Management
Tetanus prophylaxis, antibiotics and oxytocin are administered and fluids are continued until the mare is recovered.
Colostrum should be obtained as soon as possible to administer to the foal and the foal should be introduced to the mare as soon as she is steady on her feet.
Rectal examination for the next 5-7 days will help assess uterine size and involution.
Common complications following surgery include:
- Retained placenta due to uterine atony following extended uterine manipulation: place on oxytocin drip
- Uterine and vaginal infections: gentle uterine lavage with saline
- Post-surgical ileus and constipation: ensure sufficient fluids and give motility-enhancing drugs
- Limb swelling: gradually increase hand walking and paddock turnout
- Incisional problems such as infection, dehiscence: treat accordingly
- Adhesions and colic: may need another surgery or adhesions may be broken down during rectal exam
The earlier the operation is carried out the better the prognosis, and caesarean sections can have very good outcomes with both mare and foal recovering. Successful outcome percentages fall as mares reach 20-25 years of age.
However all foals delivered by caesarean section are classified as high risk and have to be managed in specialist facilities.
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Equine Reproduction and Stud Medicine Q&A 20 |
References
Mair, T. (1998) Equine medicine, surgery and reproduction Elsevier Health Sciences
Knottenbelt, D. (2003) Equine stud farm medicine and surgery Elsevier Health Sciences
Turner, A. (1989) Techniques in large animal surgery Wiley-Blackwell
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