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Spaying—surgically removing the female reproductive organs—is routinely done in small animals like dogs and cats. It keeps the animals from coming into estrus, and is a fail-safe method of preventing pregnancy. Spaying in dogs and cats is generally safe, not terribly expensive, and allows rapid healing with few complications.

In horses, spaying is not common, and means removing the ovaries rather than the uterus and ovaries as in dogs and cats. Owners generally learn to accept that their mares may show some behavioral and personality changes during heat periods. Though some mares don’t seem to show significant signs of being in heat, others become moody, sensitive, and distracted. Mares in heat may squeal, kick, flinch when touched over the loin and flank, tend to buck or bolt when ridden, or display other behaviors that can be serious enough to make the horse unusable for several months during the spring season. Besides being difficult to ride, a vocalizing mare in heat can also distract any stallions (and sometimes even geldings) within sight or hearing.

These behaviors often diminish after the strong estrous cycles of spring and early summer, and mares resume their normal behavior. Ovarian tumors or abscesses can sometimes produce behavior similar to what is seen during estrus, but at another time of the year. If this happens, owners should have a veterinarian check to see whether the mare has this type of problem, and if so, whether spaying is a suitable treatment.

Owners considering spaying to alleviate undesirable behavior must consider several factors. First, spaying is permanent, and spayed mares will never be able to ovulate, so the owner should be certain that this is understood and accepted. Second, spaying is expensive, requires some hands-on aftercare, and includes a period out of work during recovery. Third, there may be complications like hemorrhage, infection, colic, herniation, or damage to internal organs. Finally, if the spaying is being done to reduce behavior problems, there is always a chance that the mare’s behavior has actually been a result of her personality or a training flaw, and in these cases spaying will have little or no effect on how she acts in hand or under saddle.

Once the decision to spay has been made, the owner should discuss options with the veterinarian who will perform the surgery. Spaying can be done under local or general anesthesia and by using a vaginal, flank, or ventral incision. Each method has a different cost and a varied set of risks, and some approaches are better than others for removing enlarged or diseased ovaries. Owners should understand the risks and have all questions answered before scheduling this surgery for their mares.


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