When to Spay
and What Spaying Involves
© 1999 Cherry Hill
removing a mare's ovaries is not as commonly performed as gelding,
there are circumstances in which spaying a mare can be advantageous.
Some breed registries allow a tentative registered mare to move up to permanent
registration when she is spayed.
If a mare has developed dangerous behavior as a result of hormone imbalances resulting
from an ovarian tumor, removing the ovaries can redeem the mare's chance
at a useful non-breeding role. Mares with granulosa tumors most often display
wicked habits such as squealing, biting kicking and exhibiting stallion-like behavior.
In 90-95% of the cases, surgical removal of the tumor and/or ovaries eliminates
the undesireable behavior. Mares that have developed cresty necks and voice changes
most often retain the characteristics after surgery.
Less dangerous mares, but those with irritable, fussy or silly periods every
month may be regarded as a nuisance in terms of show, race or ranch work.
If a mare is valued, but not for breeding purposes, spaying may provide
the necessary alternative to produce a more solid performer.
A non-surgical treatment for mares with undesirable estral behavior is the administration
of an oral synthetic progesterone, Regumate. Progesterone is the calming
female hormone responsible for maintenance of pregnancy. Regumate's inhibiting
effect on the occurrence of the estrous cycle might provide temporary help
during a prospective broodmare's show or race career.
If more permanent measures are required, the mare owner must look to surgical
alteration. Dr. Robert K. Shideler of Colorado State University's Veterinary
Teaching Hospital outlined three methods of removing the ovaries.
Major abdominal surgery under general anesthesia is the most expensive method
involving the longest recovery period, yet may be the only option available to
horse owners in many locations. The ventral midline incision made from the
umbilicus toward the udder gives the practitioner easy access to the ovaries.
The surgeon has absolute hemorrhage control which is essential when dealing with
the highly vascular ovary with a tumor. Major vessels are tied.
The patient usually remains in the hospital for observation for 10-12 days, then
is restricted to box-stall/paddock confinement for an additional 30 days.
It is usually 90 days from the date of surgery until the mare can return to training.
As with all major abdominal surgeries, there is the risk of anesthesia and post-operative
complications such as colic.
flank approach is usually performed with the horse standing in stocks, under the
influence of a tranquilizer and local anesthetic. Often a four inch incision
is made in both flanks to allow the surgeon easier access to each ovary.
Removal can be made with an emasculator, such as used in the gelding process or
with a chain loop ecraseur.
is quicker than with abdominal surgery. Beginning with one day for observation
in the hospital, the horse should spend 10-14 days in stall/paddock confinement
and a return to work 30 days from the date of surgery. Generally the flank
method provides few complications but does yield minor scars.
The vaginal approach is the fastest, most inexpensive method, costing about 1/4
that of abdominal surgery. However, the vaginal approach requires
a higher level of technical experience and may not have widespread availability.
Mares must be free from reproductive tract infection and are routinely put on
antibiotics before and after surgery.
It is especially important when choosing this method to fast the mare for 24-36
hours prior to surgery to ensure minimal intestinal fill. The mare
is restrained in stocks, under the influence of a tranquilizer and local anesthetic.
The surgeon makes entry through the vulva and a small incision is made in
the vagina. The ovaries are severed from their attachments by utilizing
a chain loop eraseur. No ligation of vessels is required and no vaginal
sutures are necessary. There is little trauma and jeopardy involved in the
the mare is usually kept standing in crossties for 24-48 hours because laying
down might allow protrusion of intestine through the incision. During
this time she should be periodically hand-walked for exercise. After 3-4
days in a box stall, she can be turned into a paddock for a week, and then returned
When to spay a mare depends
somewhat on the reason for the surgery and the subsequent method of choice.
Abdominal surgery would be necessary for the mare with a large ovarian tumor and
could be performed at any age. It would also be appropriate for routine
ovariectomy of the yearling as the longer recovery time would not interfere with
a performance schedule. From a technical standpoint, both the vaginal
and flank methods are best suited for a mare 2-3 years of age whose mature proportions
allow the surgeon room to operate.
Spayed mares no longer have estrous cycles, so do not exhibit estrous behavior.
Otherwise, there are no behavioral changes associated with an ovariectomy.
Likewise, other than the absence of ovaries and the decrease in estrogen production,
there are no physical changes. The mare's metabolism does not slow down;
she does not become an easier keeper; she does not gain weight more readily unless
the hand that feeds is too generous.
Spayed mares do not lose their feminine features. Your mare
will look as sweet as she did before surgery. More important, she will behave
Removing a mare's
ovaries is a permanent way of altering her estrous cycle and behavior. After
careful consideration of breeding potential and intended use, spaying may be the
answer to one of your mare management questions.