Yearling Prices for LI-Infected Horses Lower

But the bacterial disease doesn't affect their earnings potential on the racetrack.

There is some bad news for the sellers of young Thoroughbreds that have suffered from Lawsonia intracellularis (LI) infection, according to Dr. Michele Frazer, one of the speakers during the American Association of Equine Practitioners convention in Las Vegas Dec. 5-9. But there is good news for the buyers of those horses.

Frazer, who performed a study at Hagyard Equine Medical Institute in Lexington, reported that LI infection negatively impacts the prices of yearlings sold at public auction but doesn’t affect their future earnings potential.

LI infection first was recognized in horses in the 1990s and has been diagnosed increasingly in Central Kentucky, other parts of this country, and Canada, Frazer said. It causes a disease of the intestines that most commonly affects foals or weanlings three to eight months of age, but the problem also has been diagnosed in older horses. Sick horses are lethargic, experience weight loss, and have a rough hair coat. Their body condition is poor, and they have a pot-bellied appearance. 

Frazer reviewed the medical records of Thoroughbreds diagnosed with LI from January 2002 through January 2008 at Hagyard. There were 116 horses in the group. Thirty-six of them were sold at public auction as yearlings, 30 raced, and 12 both were sold at public auction and raced. Frazer obtained the sale and race records for the horses, and each horse’s results were compared to the results for the other progeny of its sire.

The LI-infected horses sold for prices that were significantly lower than the average for their sires’ other progeny. However, for the ones that  raced, their earnings were not significantly different than the average for their sires’ other offspring.

Based on the study, buyers shouldn’t avoid purchasing young horses previously infected with LI, which is a bacterium, because they are worried about the illnesses’ long-term effects. But the animals’ sellers face a challenge in finding them new homes because their lower prices suggest that they don’t look as good physically as yearlings as other horses.