There are many challenges you might face when breeding maiden senior mares (mares 15 years of age or older that have not previously had a foal). In this video, we hear from reproductive specialist Karen Wolfsdorf, DVM, DACT (Diplomate of the American College of Theriogenologists). She is a partner in Hagyard Equine Medical Institute in Lexington, Kentucky.

(Editor’s note: The content of this video is the expert’s approach to the topic. Please consult with your practitioner if you have questions.)

Challenges of Older Maiden Mares

“You are starting from scratch in a mare that has never had a baby, and now she’s 15, 16, 18 years of age,” noted Wolfsdorf.

She said there are a couple of things that are the same in aging mares whether they have had a foal or not. One is the issues with aging oocytes (eggs) of the senior mare.

“The other thing that is going to change is the quality of the endometrium,” she added. “The ability of that mare to be able to feed the developing embryo properly and enough.”

Unique to the older maiden mare is that her cervix is never going to have been opened to foal, noted Wolfsdorf. “In older mares, their cervixes are very tight,” she said. “They don’t relax properly, and they can become a little fibrotic. So, they don’t allow fluid to go out normally.”

Wolfsdorf explained that mares have a natural inflammatory response in the uterus when they are in heat and when they are bred. The cervix in a normal mare opens to allow that fluid out of the uterus. In the older mare, the cervix doesn’t relax properly and the uterus might not be able to contract enough to push the fluid out.

Wolfsdorf said that senior maiden mare is going to need a lot more help in opening the cervix and pushing that fluid out pre- and post-breeding.

Bypass the Problems

Veterinarians have many tools to help these older maiden mares to get pregnant and produce a foal. However, there also are ways to bypass the senior mare’s reproductive problems in order to get a foal.

Mares can be bred and the embryo flushed out and transplanted into a recipient mare to carry to term. Intracytoplasmic sperm injection (ISCI) also can be used. This is where an egg is removed from the mare and a single sperm is injected into it before the fertilized egg is placed in a recipient mare.

“This way you are bypassing the older mare’s uterus, and we are using a younger mare to provide a nice environment where that embryo can grow,” noted Wolfsdorf.

Final Words

There are many tools in the reproductive veterinarian’s toolbox to help you successfully get a foal from a senior maiden mare. “Work together with your veterinarian, your nutritionist, your farrier, your dentist…and together to try and produce a happy, healthy foal,” said Wolfsdorf.

(Editor’s note: There will be more videos about reproduction in the senior mare and stallion coming soon!)

About Dr. Wolfsdorf

Dr. Karen Wolfsdorf attended veterinary school at the University of Florida and graduated in 1992. After completion of her DVM, she began an equine field service internship at North Carolina State University. In 1995, Dr. Wolfsdorf completed a residency in Theriogenology at the University of Florida and became board certified in Theriogenology. Before coming to Hagyard Equine Medical Institute, she spent time working in Australia with Dr. Pascoe at Oakey Veterinary Hospital. In 1996, Dr. Wolfsdorf joined Hagyard as an Associate and in 2002 she became one of the first two female members of the Practice. Dr. Wolfsdorf’s main area of interest is infertility in the mare and problems during pregnancy. She has authored many chapters on equine reproduction as well as lectured worldwide and published research regarding progesterone, retained endometrial cups and equine twin reduction with cranio-cervical dislocation.

Further Reading