Advancements in Equine Reproduction Examined at KTFMC Meeting

LEXINGTON, KY–As the calendar turns over to June and the 2023 breeding season nears its close, the Kentucky Thoroughbred Farm Manager's Club (KTFMC) focused its monthly meeting on advancements in the equine reproductive field and how the latest research, as well as new treatments and diagnostic tests, might have practical application for farm managers at this point in the breeding season and on into next year. Held Tuesday evening at Copper Roux in Lexington, the event featured presentations from three equine veterinarians.

Dr. Emma Adam, who specializes in equine veterinary outreach for the University of Kentucky's Gluck Equine Research Center, provided an update on this year's breeding season. She discussed several issues that have been problematic for breeders this year and pointed out how farm managers can be involved in advancing research efforts addressing those concerns.

While Rotavirus was not nearly as prominent this year as it was during the outbreak in Central Kentucky in 2021, Adam said that some farms were hurt by the diarrheal disease in 2023. She explained that there is work being done this summer to test a new vaccine that would protect against the most recent strains of the virus and said that they are seeking the help of local farms as researchers are collecting blood samples from foals that developed Rotavirus this year.

“That is going to help us identify antibodies that naturally responded to the infection and [help us] move forward with the idea of producing synthetic antibodies that could potentially help us in the face of not having that vaccine to hand quite yet,” she said.

Current research efforts are also going toward addressing Nocardioform placentitis and Leptospirosis. Adam said that research is being conducted on mares that developed Nocardioform placentitis and initial results suggest that an early-warning diagnostic test may be available in the future. Meanwhile, a new serovar has been identified in North America for Leptospirosis and a number of asymptomatic horses are testing positive for the bacterial disease across Central Kentucky.

For managers that dealt with Nocardioform placentitis this year, or if they know of or suspect the presence of Leptospirosis on their farm, Adam urged horsemen to contact the Gluck Center's research team.

“This summer, if you have mares that don't have a good reason for being empty, please give us a call,” Adam said. “We would love to test them free of charge to try and see if these mares are potentially carriers of Lepto. We're only as good as the data that we get. When we get those samples into our diagnostic lab, that is the material we can use to help you not just from a practical basis of diagnosing and getting the material for us to do research on, but when we have those numbers, we can go to the grant funding agencies and say we need some money because this is 'this big' of a problem.”

Adam also shared that recent research on fescue is focused on its presence in pastures throughout the winter months. Fescue toxicity in mares is a common concern in the spring, but Adam noted that ergovaline–the alkaloid produced by fescue that causes the symptoms of fescue toxicity in mares–can be present in pastures year-round.

“In the winter, we normally think that our fescue isn't growing and that we don't have ergovaline to worry about in our pregnant mares,” she said. “That absolutely is completely and totally not the case. We had lots of farms this winter where the only thing growing was fescue and that fescue is hotter than Hades, so it has plenty of ergovaline.”

During the evening's second presentation, Dr. Maria Schnobrick of Rood & Riddle Equine Hospital discussed a new service that Rood & Riddle is offering to promote the regression of endometrial cups.

Endometrial cups, which form on the uterine wall at around 35 days of gestation to promote pregnancy, secrete eCG (equine chorionic gonadotropin) and prevent the mare from normal ovulation. These cups persist until 100 to 150 days of gestation regardless of the viability of the embryo.

Schnobrick and her colleagues have made progress in developing a treatment for regressing these endometrial cups when a mare loses a pregnancy so that she can return to a normal cycle in a shorter amount of time. Schnobrick said that current treatments, like laser treatment, have inconsistent results and only about a 50% success rate. However, she has found promising results from using Settle, an immune stimulant that is used to treat endometritis.

In an experiment conducted in collaboration with Dr. Carleigh Fedorka and Dr. Mats Troedsson, 16 mares were aborted at 40 to 45 days of gestation. One week later, they received their first injection of Settle. After another week, they received a second injection. The experiment produced statistically significant results when, an average of 23 days after their first treatment, 80% of mares were cycling normally compared to 33% of mares in the control group.

Schnobrick said that this year, she had three mares that experienced pregnancy loss at 60 days and were able to get back in foal after receiving this treatment at Rood & Riddle. She noted that she has also seen positive results when treating mares that have retained endometrial cups from the previous breeding season and are not cycling regularly.

Hagyard Equine Medical Institute's Dr. Kristina Lu presented on advancements in diagnosing endometritis using N-acetylcysteine and she also discussed the benefits of pregnancy monitoring at this stage in the breeding season.

According to Lu, the current methods for diagnosing endometritis through a swab culture or a lavage of the uterus produce inefficient results. She noted that about half the time, a mare can have endometritis but test negative in a swab culture.

Lu's research efforts have gone toward using N-acetylcysteine to help break up mucus and free bacteria from the endometrium in order to better test for the presence of infection. In one experiment, 59 mares were diagnosed for endometritis. Using a lavage diagnostic test, 81% tested negative. But when the same mares were tested after receiving acetylcysteine, only 27% tested negative.

Lu also discussed the importance of pregnancy monitoring and the benefits of compiling a list of “problematic mares” ahead of next year's breeding season.

She explained that placental abnormalities from this year's foaling could be one of the strongest indicators for potential issues ahead of next year's foaling season. A mare could have a normal foaling, but a slight issue with her placenta–like evidence of subtle ascending placentitis or if the cervical star did not rupture regularly–could prove to cause problems down the road.

“This mare is raising her hand saying, 'The next pregnancy, I might not be normal,'” Lu explained. “So this mare might go on your list. She's definitely one that is worth watching in the future.”

Also during Tuesday's KTFMC meeting, information was presented on the Gerry Dilger Equine Scholarship Foundation's Irish National Stud Scholarship. Learn more here. Also, Godolphin USA's Charities Manager Katie LaMonica discussed this year's Thoroughbred Industry Employee Awards. Nominations for those awards are open now through July 16 and can be accessed here.