Dr. Fairfield Bain monitors a sick foal at the Hagyard, Davidson, McGee Equine Clinic near Lexington, Ky.

Dr. Fairfield Bain monitors a sick foal at the Hagyard, Davidson, McGee Equine Clinic near Lexington, Ky.

Anne M. Eberhardt

2001 Breeding Season Crisis: Many Mares Losing Foals; Links to Related Stories

Published in May 12 issue of The Blood-Horse
By Kimberly S. Graetz, with additional reporting by Deirdre B. Biles, Dan Liebman, and Ray Paulick

Two "syndromes" of unknown origin that began in late April are causing Central Kentucky farms to lose an excessive number of foals and fetuses.

The first syndrome results in what broodmare owners know as "red bag," or premature placenta separation. The placenta comes out before the foal, often causing the foal to suffocate if the birth is unattended. The second syndrome was discovered a short time later, when veterinarians began to perform 60-day ultrasound fetal checks and found many mares either were not pregnant or in the process of ending their pregnancies.

Some farms have experienced losses from 25-75% of next year's foal crop. There is no evidence the problems are slowing down.

It is unknown how many foals/fetuses have been affected. Dr. Doug Byars of the Hagyard-Davidson-McGee veterinary firm near Lexington, said there were 14 "red bag" foals admitted to the clinic on May 4. Those foals have a high mortality rate, with only about 50% being saved.

Gus Koch of Claiborne Farm near Paris, Ky., called the situation "the biggest crisis we've ever faced in this industry since I've been around. What I'm hearing is this is devastating." Koch said a May 5-6 check of about 40 mares at Claiborne found 25% of them no longer pregnant. "Most of those were past 60 days," he said.

Dr. Lenn Harrison, director of the University of Kentucky's Livestock Disease Diagnostic Laboratory in Lexington, said his staff has performed an unusually high number of necropsies and tests on aborted fetuses and dead foals. The sudden nature of the problem has prevented the lab from compiling official numbers of incoming horses, but more than 60 have come in on some days. Normally, the average daily number of aborted fetuses sent to the lab at this time of year is five or six, with a slightly higher number of dead foals.

No one knows the cause of the excessive numbers of late-term abortions, stillbirths, and weak foals, or of the early embryonic losses. Harrison termed it a "significant" problem and suggested the late-term losses and early abortions probably trace to the same cause.

Byars said one abnormal occurrence associated with the late-term problem is that some mares start foaling while standing up. "Some foals are early, some at term, and some are overdue," Byars said. "The mares usually have developed an udder, but some are agalactic (don't develop an udder or produce milk normally). The foals don't want to breathe. There are a lot of stillbirths. Many of the foals that make it to the hospital have low white counts (the blood cells that fight infection), are septic (system-wide infections), and dehydrated."

There are many theories as to the cause of these two seemingly related problems, ranging from blaming this year's extreme tent caterpillar crop to mycotoxins or endophytes in the grass. Byars said the mycotoxin theory is the most plausible due to this year's unusual weather conditions.

"We went from spring to summer with a freeze in between, and that is good for fungus growth," Byars said. "The opportunity for fungus proliferation is extremely high, and the concentration of the toxins in the dried-out grass could contribute to the problem."

Similar weather conditions, including a late spring freeze, existed in 1980, when an unusually high number of abortions was reported at a small number of Central Kentucky farms. No cause was pinpointed.

Dr. David Powell, an epidemiologist at the University of Kentucky's Gluck Equine Research Center, has been involved in a series of meetings with breeders, veterinarians, and pasture management specialists since being alerted to the problem. "There's a lot going on at the Diagnostic Lab, concentrating on the possibility of an infectious disease agent," Powell said. "The other aspect being closely monitored is the possibility of some toxin in pasture. The investigation also includes looking at other aspects, including the phenomenal increase in caterpillars, or any other avenues."

Powell said on May 7 he had received unconfirmed reports of a similar syndrome in at least two other states north of Kentucky. "If that is true, it suggests we are not dealing with an infectious disease. My personal observation would be, based on the sudden nature of this, that it doesn't suggest we are dealing with a contagious disease."

Like Byars, Powell cited the unusual spring weather and its possible effect on pastures. "We know very definitely that fescue can be a problem," Powell said, "but we are seeing this condition on farms where there is little or no fescue. That's not to say there is no endophyte or toxins in other strains. We are not restricting our investigations into fescue toxins. We are looking at other pasture grasses."

Powell said no evidence suggests herpesvirus as a cause of the abortions.

Byars said current recommendations are to treat every foaling mare as a high-risk foaling situation. Veterinarians are administering domperidone and taking other steps to counteract some of the symptoms associated with the foaling problems.

He also suggested mowing pastures in spite of the drought conditions that currently exist in the region. "Many people stopped mowing when conditions got dry," Byars said. "I am suggesting mowing, although the damage may already be done."

The Taylor family's Taylor Made Farm near Nicholasville, Ky., first detected a problem in late April after some clients requested fetal sexing ultrasound exams of mares believed pregnant 60-65 days. The farm learned that an abnormal number of mares were showing up not in foal.

"Then we went and checked all those over 60 days and realized it was a problem," said Duncan Taylor. "Something wasn't normal." Taylor Made contacted the Gluck Center and the investigation began.

"We have tested the grass and water, drawn blood, tested fecal samples," Taylor said. "We called in our pasture management person and nutrition specialist. We wanted to leave no stone unturned...I can just say that the mares we have checked 40 days and above, there is about a 25% loss."

Among other farms that have confirmed having unusually high numbers of abortions are Three Chimneys Farm near Midway and Overbrook Farm near Lexington. One veterinarian suggested many breeders may be unaware that their mares have aborted because palpation checks may not determine whether a fetus is alive.

"I think what is called for at this point is a deliberate and rational approach," said Three Chimneys president Dan Rosenberg. "We need to gather information, and we need to give it to the Gluck Center (at the University of Kentucky), which I think is a great resource."

Overbrook Farm's Ric Waldman said the Lexington farm has experienced a "larger than usual" number of early fetal losses but no unusual pattern on late-term losses.

"I heard of one mare (that aborted) this morning that had been bred to Storm Cat," Waldman said. "I would assume no stallion is immune, as widespread as I'm hearing this is. This could have a widespread effect on stallion revenue, breeders' revenue, sale company revenue. No breeder would be immune to being affected by this."

Related Stories:

Interview With Dr. Byars on Foal Losses

Questionairre Seeks Information About Foal Losses

1980 Outbreak Eventually Discounted as 'Artifact Epidemic'

Epidemiologist Q&A on Foal Losses

Diagnostic Lab Seeks Answers

Farm Managers, Vets to Meet

UK Vet Science Department Memorandum to Farms.