This section is on equine reproduction. These are all questions that have been submitted or that I have been inspired to talk about because of a question submitted. If you have any topics that you would like to have discussed please feel free to email me with the topic or question.

I have heard that twins in mares are bad, why?

The uterus in domestic animals is comprised of a body and two horns that make a Y-shape. Mares, unlike the females of the other domestic species, have very short uterine horns and a large uterine body. Most mares simply do not have enough uterus to maintain two fetuses. They will carry the two fetuses until around eight months of pregnancy then abort both of them. Thus, it is imperative to diagnosis twins early in the pregnancy in order to remedy the problem before the mare aborts both of them.

How long are mares pregnant and when are foals weaned?

Mares are pregnant from 330 to 350 days. The weaning age of foals varies but most are weaned around six to nine months.

Hi my mare is due near the end of June and today I noticed one side of her udder was swollen. Her temp is normal. The udder isn't hot or painful. I didn't see any cuts bug bites or ticks. It wouldn't be filling with milk already would it??? If not do you have any idea as to what it may be?

Submitted by: Dina Minchey

I apologize beforehand but experience makes me ask this -- are you sure of the due date? Is this her first foal? Is it very swollen or slightly? Can you express any fluid out of the teat?

It is possible that the udder is already filling with milk. Some mares especially with the first foal start udder development as early as 3 months before the foal is due but that is not very common. And given that it is one side only, it seems a little unlikely. Since it does not seem to be a problem for her right now I would monitor it and see if it becomes hot, painful, more swollen, red and inflamed, etc. Watch the other side also and see if it becomes swollen. If it gets worse, I would have your vet check it.

One word of caution if it is indeed early milk production than there is a possibility that by the time the foal arrives the mare will not have any colostrum. If she is starting to produce milk now, I would have your vet check the foal 24-36 hrs after birth to make sure that is received adequate colostral antibodies.

I have researched and answered these questions to the best of my ability. But I am human and make mistakes. If there is any part of my answer that you feel is incorrect, please let me know. The last thing I want is to disseminate false or incorrect information.