Ask The Vet: Equine Reproduction

Courtesy of AAEP

Question: If a mare is overly fat when in foal, would that cause her to prolapse at foaling time?

Answer: There is no evidence to suggest that obesity, at the time of foaling, increases the incidence of uterine prolapse.

Question: I have a 20-year-old broodmare that last foaled in 2008. She was in foal after one artificial insemination (AI) cover in 2005,07 and 08. We have been unsuccessful in getting her into foal since, trying three times in 2009, five times in 2010, using two different studs. Our veterinarian did a complete work up and found nothing wrong with her reproductively and is very healthy according to our veterinarian. We have spent thousands in our attempts. Many people say live cover is the only way to go. What would you suggest? Thank you for your assistance as we are at our wits end!

Answer: Your mare represents a bit of a diagnostic challenge. When I approach cases such as yours, there are several things I eliminate first before moving on to more complicated things. First, I would make sure to get a good representative culture. By that I mean, a culture obtained when the mare has at least a 35mm follicle and good uterine edema. If that is negative, I would check her thyroid levels and if she displays symptoms (obesity, cresty neck etc.) check her for metabolic disease. If these tests are normal, and you have been ensuring that ovulation occurs within 24 hours of breeding, I would next examine the semen closely. It is good that you tried two different stallions. Did you determine the progressive motility and the total number of cells you were breeding with? If you have bred with at least 1 billion progressively motile cells and have still come up empty, I recommend you try embryo transfer.

There is a possibility that your mare may be conceiving and then losing the pregnancy before you are even able to visualize it ultrasonically. The incidence of early embryonic death increases with age and could be the cause of your problems. If you fail to get an embryo when attempting to transfer, it is possible that your mare could be suffering from occlusion of one or both oviducts.

If this is the case, your options are greatly reduced, with oocyte transfer being your best chance at producing a pregnancy. The only advantage of live cover over AI is the extremely high number of sperm cells provided at the time of insemination. This always increases your chance of a successful fertilization. However, if you are breeding with properly prepared cooled semen, I don’t consider live cover to be a big advantage. I hope this helps answer some of your questions and good luck with your mare.

Question: I have a mare that is 18-years-old and has never had a foal due to using her in performance. Now that she is retired because of arthritis in her front right leg and blind in her left eye, would you consider her too old to have a first foal?

Answer: I do not consider your mare too old to carry her first foal. There are some things to consider when breeding the older maiden mare, which we have addressed with other people so check out some previous answers for those. That being said, your mare presents some additional considerations. Most importantly, you need to consider her potential mothering ability due to the loss of sight in one eye. If she only recently lost sight in that eye, I would recommend you wait until a little later in the breeding season so that she has had time to adjust. If she has been blind in that eye for quite some time, I would not be as concerned.

However, do not forget after she has foaled, she will not be able to see her foal on that side, which can present problems when the foal is first trying to nurse. I would strongly recommend you monitor her foaling and be there as the foal attempts to nurse as it may be necessary to either hold the mare still or encourage the foal to stay on the sighted side until both mother and foal are comfortable with the whole process. The arthritis doesn’t concern me unless it is so severe that she has a very difficult time getting around. If that is the case, I would strongly recommend embryo transfer.