Spaying mares: A method to permanently manage behavior
January 28, 2013
Some people may have a preference in owning a certain sex of horse such as geldings, mares or stallions. There are obvious advantages to owning mares and stallions due to being able to not only use the horse for recreational or performance needs but possibly additional income through reproduction. Granted, some owners may prefer a gelding over a mare or stallion simply due to the fact the gelding will not display certain reproductive behavior that maybe annoying, distracting or even dangerous in some situations. Many mare owners who use their horses for performance purposes such as showing, rodeoing or racing may actually attempt to alter the mare's estrus or heat cycle. When a mare comes into estrus, the time that she is receptive to being bred to a stallion, it's not unlikely that she may "horse around." Meaning, she maybe behave differently when in estrus and squeal, kick, frequently urinate and or display winking of the vulva. Riding or competing on such a horse can be difficult hence the use of methods to control her heat cycle such as using an oral prescribed substances called Regu-mate which makes the mare's body think she is in foal due to a high concentration of circulating progesterone supplied by the medicine.
However, some mare owners may resort to a more permanent method of controlling unreasonable estrus behavior and consider "spaying" their mare. When a mare is spayed the ovaries are removed. By removing the ovaries, estrus behavior typically deceases due to a decrease in various hormones such as estrogen that promote such behavior. An owner may choose to have their veterinarian spay or perform an ovariectomy on a mare if she has an ovarian tumor – at that point only one ovary may have to be removed. Typically, the ovary will be removed if the tumor continues to grow and infertility problems exist. In terms of how an ovariectomy is performed it will depend on the veterinarian performing the surgery. Keep in mind that spaying a mare is similar to castrating a stallion and should only be performed by a veterinarian. The surgery was first performed in the early 1700's by French veterinarians by actually crushing the ovary, an approach called ecrasuer (crusher) and they would go through the vagina or by making a small incision in the flank of the mare. The procedure was considered quite extreme and dangerous and later a French law prohibited spaying mares unless it was a unique case.
One of three surgeries can be performed when removing the mare's ovaries: colpotomy, flank grid or ventral midline celiotomoy and laparoscopic ovariectomy. The reported surgery of choice by most practioners seems to be the laparoscopic ovariectomy and is preferred to be performed with the mare standing. The procedure allows the surgeon to make an incision in the abdominal wall in the vaginal cavity and then through a series of procedures the ovary or ovaries are removed. The procedure is considered to be a major but elective surgery and carries some risks and some mares may continue to cycle and display behavioral problems. More importantly this procedure can allow a mare to typically return to work within two weeks. There are myths associated with spaying mares such as the mare will not longer appear to look feminine or like a mare and the mare may gain excessive weight. There is no scientific data to support either claim. However, mares undergoing the flank method surgery may have scarring or permanent blemishes. As with any surgery there are always risks involved but because this surgery can be performed while the mare is standing, recovery time is generally fairly short. A mare just coming out of surgery will generally be placed in a stall to allow any sedation or tranquilizers to wear off.
Postoperative care generally includes a daily dose of antibiotics such as penicillin for five days, water can be immediately offered and feed should be held for a few hours after surgery (two to four hours, depending on consultation with your veterinarian). Some mares may also require a NSAID (non-steroidal anti-inflammatory drug) such as phenylbutazone or flunixin meglumine (Bananime) for severe pain. Approximately a week later and depending on your veterinarian's recommendation the mare should be examined to determine the status of how the incision is healing. If the incision has closed, the mare can return to light work and pasture. As with any surgery some complications may exist such as delayed healing or hematoma or abscess may form. In some cases an incision made to close to the cervix may cause a tear as well as abdominal adhesions, which could lead to colic. Death is rarely reported as complication from this surgery but always a potential risk when performing a surgery.
If you are considering having your mare spayed first consider if you will ever want to breed her and be sure to onsult your veterinarian. The practice is more commonly performed in mare/molly mules that are used for riding purposes. Female mules like mare horses will express signs of heat and maybe very temperamental during estrus. Many mule owners have elected to spay their mare/molly mules to discourage such behavior. Keep in mind this is a permanent procedure and in some reports not all mares discontinued their ill behavior, which maybe learned behavior, so consider all options prior to committing to the surgery.
Amy McLean is the University of Wyoming Equine Specialist