Early Fetal Loss Low; Caterpillars Involved

According to Dr. Richard Holder, a practitioner with the Lexington, Ky., firm of Hagyard-Davidson-McGee who specializes in mare reproduction and fetal sexing, early fetal loss is occurring this year as it did last year, just at a much lower rate.

"It is out there," said Holder of early fetal loss associated with Mare Reproductive Loss Syndrome. "There is a low incidence. There are a lot of farms with no problems. And it appears to be caterpillar-related."

Holder said that even a month ago he was not a believer in the caterpillar theory, "But I am now. Those people who took the precautions of keeping mares up and minimizing exposure to pastures and spraying for caterpillars aren't having problems."

One complication to protecting horses, he said, is that even if a farm manager/owner does a good job on caterpillar eradication on his own property, adjacent land could be loaded with caterpillars that spill over onto the horse farm. "You can get them off your farm, but neighboring farms could cause problems," Holder explained.

However, Holder said there are some people turning mares out all night and think they have no caterpillars and have had no losses. He is keeping a close eye on those mares.

Holder is seeing some mares with cloudy placental fluids and compromised fetuses which don't survive, but again, it is a much lower incidence than last year.

One of the big questions is whether mares which had pregnancies affected last year during the crisis were at higher risk this year of losing foals. Holder said no.

"That doesn't seem to be a deciding factor if they were affected last year," said Holder. He said it seems to be more related to exposure and whether the mare was bred early and susceptible during a specific time.

"The good news," said Holder, "is that we think we know what the source is and it's definitely not as widespread. There are heavy caterpillars where the problems are." By Kimberly S. Graetz