Steps you can take if your mare is still open late in the season.
By Megan Arszman
Breeding season is winding down, but your mare is still open, and you’re starting to ask questions. If you followed Dr. Margo Macpherson’s advice from the April Reiner, you asked your veterinarian to perform a breeding soundness exam (BSE) on your mare to determine why she’s struggling to get pregnant and carry to term. Once the results come back, you might find yourself asking, “What’s next?”
It’s time for another conversation with your veterinarian, according to Ryan Ferris, DVM, Dipl. ACT, who owns Summit Equine Clinic in Gervais, Oregon, with his wife, Dora Ferris, DVM.
“We look at what’s limiting the fertility of your mare,” he explained. “Sometimes, a breeding soundness exam can rule out some issues, but there are certain parts of the mare’s reproductive system that we just can’t evaluate very well with a BSE, like the oviduct.”
Most of the time, the issues revealed in the results of a BSE are treatable, but that can take time.
“Your mare might have a uterine infection, which can be treated within three to five days,” he explained. “Or, there are other issues that could take longer to treat. If it’s late in the breeding season, you might be breeding her in June, which means she’ll foal in May. That’s pretty late in the year.”
That situation creates a quandary for you as the breeder: either continue on the path to breed your mare this season, knowing you’ll have a late foal next year, or give your mare a year off from breeding to reset her cycle and plan to send her to the breeding shed the following year—well before June.
Ferris pointed out that not all hope is lost, though. There’s a way to have a foal next year, reset your mare’s cycle, and never miss a single year of foaling.
“There are a multitude of ways we can work with a mare that did not pass her BSE this year,” Ferris shared. “Most times, a negative result doesn’t have to mean the end of your mare’s broodmare career. It just means it pushes us to use additional reproductive technologies so we can hope to get a foal from that mare in the future.”
Breeding Technology
Two of the options Ferris offers to his clients are embryo transfer and in vitro fertilization.
“Some people might not realize that these technologies can be used as management tools while we look at treatment options,” he explained. “Not all hope it lost.”
Ferris noted that breeders need to look at the cost of everything involved with various options available at this point before making a decision about how to proceed.
“For most mares, breeding her to carry, even late in the season, makes the most financial sense, and it’s the most cost-effective way to produce a foal,” he said. “But, you also have to look at the management of the mare and what her breeding and foaling cycle will be from then on.”
The embryo transfer option provides many advantages when it comes to managing your broodmare. In this case, Ferris would collect an embryo from your mare and transfer it into a recipient mare that would foal the following May. Your broodmare would be able to take a year off from breeding and return to the breeding shed early the following season, while the recipient mare carries her foal to term.
Embryo transfer also allows more time to treat your mare for any issues that were evident on her BSE.
“For instance, if there’s a lot of inflammation in the mare’s endometrium, it may take several weeks to completely clear,” Ferris shared. “In that case, we may be more likely to recover an embryo in which the uterus only has to support the developing embryo for a few days as compared to supporting a pregnancy to full-term.”
That means your vet can perform an initial treatment to resolve the inflammation long enough to harvest an embryo from your broodmare. Then you and your veterinary team can spend the rest of the year performing necessary treatments and allowing her uterus to rest before the subsequent breeding season.
“Oftentimes, it’s much easier to get a mare to be successful for embryo transfer than to get her to carry a foal to term,” Ferris said.
The disadvantage? The cost. While the additional cost of an embryo transfer can be intimidating, it’s important to evaluate why you’re breeding: as a hobby or as a business. If you choose to look at your breeding operationfrom a business perspective, Ferris pointed out that the cost of feeding an open mare could be more than the cost of the embryo transfer itself. Ultimately, the decision should be based around your breeding goals.
If your mare’s BSE identified a severe issue that drastically lowers the odds of her ability to carry a foal to term or even being an embryo donor, you still have options. In that case, Ferris recommends in vitro fertilization or ICSI (intracytoplasmic sperm injection).
If you choose one of those options, your mare’s oocytes will be aspirated from her ovaries. Fertilization is performed in a lab, then the fertilized egg grows for five to seven days before the embryo is transferred to a surrogate mare.
The advantage is that your broodmare just needs to have normal oocytes to be a donor. This bypasses any abnormalities in the reproductive tract and enables you to get a foal from your mare.
Your Choice
Breeding options can be mind-boggling for any mare owner, especially when you’re faced with little time to make a decision. That’s when it takes teamwork and open communication with your veterinarian or reproductive specialist to find the best fit for your broodmare, your breeding goals, and your budget.
“It’s an exciting time with the reproductive technology available,” Ferris said. “We like to think of them as ways to overcome reproductive abnormalities detected in a BSE and to help effectively manage mares in the future.”