Fertile Conformation
April 3, 2009
Breeding your mare will be much easier if she is built for the job.

The relationship between your mare's anus and vagina is especially important if you want to breed her.
From The American Quarter Horse Journal
Dr. Michelle LeBlanc has spent more than 25 years working on the mare side of equine reproduction. She knows that a mare’s external form counts when you’re assessing her ability to function as a broodmare.
Reproductive Conformation
The first thing Dr. LeBlanc looks at is the perineal conformation.
- The “perineum” is the group of muscles located between the anus and the vulva.
- Look at the vulva and the anus; they should be vertical with no tilt.
- If there’s a tilt, the rectum often looks sunken in and the vulva slants toward the mare’s head.
- It’s not uncommon for mares with a tilt to their perineal conformation to contaminate the vagina with fecal material.
When you breed your mare, there’s a good chance that you will use artificial insemination. AQHA’s “Artificial Insemination with Cooled Shipped Semen” DVD gives you a step-by-step look at the procedures for this popular breeding method. Be prepared during breeding season. AQHA members get a discount!
Another thing to look at is where the vulva sits in relation to the pelvis.
“There are some mares that may aspirate small amounts of fecal material into their vulva because there’s a large amount of the vulva that is open above the brim of the pelvis, even though they’re not tilted,” Dr. LeBlanc explains.
A mare with a tilt to her perineum or with too much of the vulva above the pelvic rim may require a Caslick’s procedure to prevent contamination. The veterinarian sutures shut the lips of the vulva down to the brim of the mare’s pelvis.
A mare with poor reproductive conformation can have:
- Vaginal contamination from air or feces
- Uterine infection/inflammation
- Urine pooling
- Difficulty foaling (resulting in rectal tears, etc.)
“If I have a mare that’s constantly dealing with infection and fluid in her uterus, the first thing I check is whether or not she needs a Caslick’s, based on her conformation,” says Dr. LeBlanc.
Causes of Poor Reproductive Conformation
Many factors can cause poor reproductive conformation. Perhaps the most common relate to physical changes in the mare that occur over time, due to aging and/or the number and size of a mare’s foals.
Physical Changes Over Time
- With age, and after carrying several foals, the broad ligaments that maintain stability in the uterus stretch, dropping the uterus further down into the abdomen.
- “If a mare has a large foal, then the uterus drops lower and eventually does not snap back, especially if the mare has had a lot of big and heavy foals.
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Foaling Injuries Can Be Caused By:
- Very large foals
- Pulling too soon before the mare has had time to relax
- Failure to open a Caslick’s
- Rips in a mare with a small vulva
Poor Body Condition
Simply being underweight can cause a mare’s perineum to tilt.
- Fat is necessary to maintain the proper relationship between the vulva and the pelvis.
- If a mare gets too thin, the lack of fat can cause the vulva and pelvis to shift out of position.
- Good body condition in broodmares is very important.
Genetics
“The other cause is that they’re just built that way,” Dr. LeBlanc says.
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3 Comments on “Fertile Conformation”
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April 10th, 2009 at 12:58 pm
I don’t think breed registries should allow horses with poor conformation to be registered. This would keep alot of these mares with a tipped vulva from producing other mares with the same problem.
April 16th, 2010 at 6:02 am
[...] several cycles before asking a veterinarian to examine her. Then they discover that the mare has a uterine infection or some other problem. By the time the condition is evaluated and treated, valuable time is lost [...]
May 21st, 2010 at 9:24 am
[...] the competency of her cervix. Maybe most important on an aged mare is the conformation of her vulva. As mares age, the top of the vulva tends to fall forward as the reproductive tract loses tone. [...]