05/20/2001 11:00PM

Searching for hope and a heartbeat

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LEXINGTON, Ky. - Even under the best of circumstances, breeding Thoroughbreds can be a tricky business. A mare may or may not get in foal and, once a foal is born, the breeder must steer it past any number of dangers, from viruses to lightning storms.

Now central Kentucky breeders are fighting an enemy that hasn't even been identified but has killed at least 1,100 near-term foals and early fetuses some 60 days after conception. Veterinary researchers and pasture specialists theorize that the cause is a mycotoxin, a mold- or fungus-produced grass toxin that horses ingest when they graze. While research continues, horsemen are worriedly requesting ultrasounds for pregnant mares and hoping that the tiny fetuses, the future foal crop of 2002, will not disappear.

"There it is. See it?" Dr. Ed Fallon, a 45-year practitioner, is dressed in the veterinarian's standard khaki jumpsuit, with a syringe, a bottle of lubricating gel, and a white hand towel in his pockets. He points at the ultrasound screen. It shows white fluff surrounded by a black space of amniotic fluid, and near its center is a faint flicker, smaller than the nail on Fallon's little finger. That flutter is proof, for now, of a foal by Peaks and Valleys out of the stakes-winner Greatcaesar'sghost.

That's good news for Fred and Nancy Mitchell, the owners of Clarkland Farm and Greatcaesar'sghost. So far, they have been luckier than some of Lexington's other commercial breeding operations, which have acknowledged losses ranging from 25 percent to 80 percent of their mares' early fetuses. Their luck may be a temporary quirk of timing. As of Tuesday, they had had just five mares ready to ultrasound at or beyond the critical 60-day mark, and four of those were "empty," meaning they'd resorbed - basically, dissolved - their early fetuses. Clarkland has 13 other mares who haven't reached the two-month point yet. Fallon, reaching into a mare and feeling for the fetus, has pronounced them in foal, but the Mitchells know that in several weeks, they too may show up empty. For Fallon, the crisis has meant more ultrasounding of mares like Greatcaesar'sghost, whose two-inch long fetus is still alive at 49 days past conception.

"The ones we're worried about the most are the mares who were checked in foal at 30 to 45 days," Nancy Mitchell said. "We wonder, are they going to hold on or not?"

"We're ultrasounding mares that we normally wouldn't ultrasound," Fallon said. "Unless you are doing it for fetal sexing, most people don't ultrasound after 30 days past conception.

The ultrasounding takes about 10 minutes and is not stressful for the mare. Fallon inserts the ultrasound wand in the mare's rectum, right above the uterus, and scans downward, looking for the telltale flicker. Someone else, in this case Nancy, holds the portable monitor up for Fallon to see. As he looks for the fetal heartbeat, he's wary of loose white flecks floating in the amniotic fluid, which suggest the mare is resorbing the fetus.

A client's mare, named Betty Van, also registers a fetal heartbeat, but something makes Fallon suspicious of the palpation.

"We're still alive here, but I'm not crazy about the way it feels," Fallon said of the fetus. "It's not as big as I think it should be, and, it's hard to describe, but it's not as tense and doesn't have the tone I'd like to feel."

Betty Van, in foal to Artax, could be a candidate for progesterone, which breeders sometimes give a mare to help her maintain a pregnancy. But Fallon shakes his head at that suggestion. "The ones I've seen on progesterone during this, it kills the fetus right through that."

For now, the Mitchells will just continue to monitor this mare along with the others and hope the heartbeat doesn't vanish. If it does, they can take some comfort in the fact that the early-aborting mares seem to be coming back into heat. All four of Clarkland's empty mares already have been bred again and appear to have ovulated. Other farms have reported a similar phenomenon, an unexpected development in mares they thought would not come into heat for as long as 120 days. This has surprised veterinarians and offered hope to breeders that they can mitigate their losses by breeding for late foals rather than giving up on their mares for a year.

Like other central Kentucky breeders, the Mitchells are doing what they can to protect their mares. They feed them a supplement that includes yeast-cell extract, which vets say will render mycotoxins harmless. Fred Mitchell has had the farm's pastures mowed and is testing 100 acres of alfalfa, clover, and orchard grass for toxicity.

And they're waiting for answers.

"We have no idea whether this is over or not," Fred said. "If the mares picked something up in their systems, we don't know if it affected them before they were bred or after they were bred. If it is a toxin, we don't know how long it was on the grass or how long it stays with them."