Spaying a mare

Spaying a mare

The spaying of a female horse, also known as a mare, is an operation called an ovariectomy which is the surgical removal of the ovaries and so preventing the continuation of the oestrus cycle. The tremendous risk of major surgery on a horse, which can be fatal, means that spaying a female horse is extremely rare in the UK. Only where the operation is absolutely required if it becomes a life saving operation, if it is due to the interference of oestrus in the mare’s performance in sports such as racing and polo, or if the mare has an hereditary condition does it is it even become considered. The very high costs of major operations on horses also act as a factor for not spaying a mare.

At what age should a female horse be spayed?

Mares are usually spayed if the operation is to remove a tumour as opposed to preventing pregnancy. It is for this reason that there is little evidence of guidelines as to the youngest age to perform the surgery. However, if a large tumour is present then it is suggested that the operation can be undergone at any age.

The operation and the post operative care

There are various methods which can be used when performing spays on mares. These include creating a ventral midline incision under general anaesthetic, creating two flank incisions under a local anaesthetic and entering through the vagina under a local aesthetic.

Ventral Midline Incision

At present this is the most used option as it is more widely available across the country than the other two methods. It is considered a major operation since the abdominal cavity is entered and a general anaesthetic is required. An incision is made along the ventral line starting from the umbilicus as is usual with the majority of spay surgeries. The major vessels connecting the ovaries are crushed and the ovaries removed using a chain loop ecraseur. This method has the longest recovery time taking up to thirteen weeks before the horse can work again. During the first two weeks of this time, the veterinary surgery will keep the horse for observation. Along with the cost of the operation, this hospitalisation is another reason as to why this method is the most expensive.

Two Flank Incisions

The horse is sedated using a tranquiliser and a local anaesthetic is given. The horse must be standing due to the fact that both sides are required to make an incision on each. The ovaries are removed using a chain loop ecraseur. This method is slightly more complicated than above but is less expensive. The horse only needs to be observed by a vet for generally one day and movement must be restricted for two weeks before the mare can begin training again in around five weeks time.

Entering Via the Vagina

The vagina is entered via a small incision by a skilled surgeon following sedation and a local anaesthetic. Due to the complicated procedure that this method presents, although this is the cheapest option, it is not widely available. Antibiotics must be administered to prevent infection. Once again, a chain loop ecraseur is used to remove the ovaries.   The horse is prevented from lying down following the surgery for up to two days with easy hand held exercise and boxed for a week. The horse can then start working again. Arguably the most favourable method, not many veterinarians have not been adequately trained to perform the surgery.


Spaying my female horse will make her fat

Female horses or mares will not become overweight as a result of the operation. There will be no decreasing of the mare’s metabolic rate. Overfeeding from the owners of the spayed horse is the most common reason for any weight gain that may be experienced.

My horse will no longer look like a mare

This is a worry many owners have when forced to make the decision as to whether or not to spay their mare. However, this is simply a myth. The mare will retain her femininity in terms of aesthetics, in other words, she will still look as much like a mare as she did before.

Spaying my female horse will get rid of any unwanted “mare-ish” behaviour

This is only true if the behaviour problems are associated with the horse’s hormones or ovaries and if the problems are a result of exhibiting oestrus behaviour. Horse behaviourists may be able to correct the unwanted behaviour without the need of an operation. It is known that many horses have been spayed for this reason but still continue to show unwanted behaviour. As a result, the owner must be absolutely certain that that spaying will overcome this problem if they want to go through with the procedure.


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