osteochondrosis

“Watch out, little foal! Don’t slip and make yourself vulnerable to osteochondrosis!”

If we adhere to the latest research on osteochondrosis development in young horses, this might be our new warning to the babies in the barn. Recent study results suggest small but significant differences exist between how much foals slip and slide when standing and osteochondrosis incidence in Warmbloods. Whether environmental factors are causally related to these differences, however, remains to be seen.

“We hypothesized that rapidly growing foals with their rapidly increasing height, housed on conventional, slippery flooring would develop osteochondrosis significantly more frequently,” said prof. dr. Machteld VanDierendonck, of the Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, in the Netherlands.

Researchers know that piglets developed osteochondrosis more frequently when they were housed on slippery flooring and overfed, so the researchers sought to determine if that finding might hold true for horses, as well. Other study results have shown that many modern domestic horses—Warmbloods, in particular—grow faster than evolution “designed” them to. This phenomenon—caused by practices such as overfeeding and selective breeding for height, among others—is also associated with developmental orthopedic disease (DOD), the researchers said.

“The aberrant standing-up behavior, characterized by abnormal limb movements that displace the limbs out of their natural sagittal plane (level posture), may cause excessive changes in peak pressure on joint surfaces,” VanDierendonck said. “This could damage the vasculature of juvenile cartilage, resulting in early avascular necrosis, and, hence, osteochondrosis.”

In her study, VanDierendonck and fellow researchers compared osteochondral lesions in 48 Dutch Warmblood foals at 6 and 12 months of age at five breeding farms. They correlated lesion presence and severity with foals’ standing-up (and sliding) behaviors between the ages of six and nine months. The researchers filmed each foal for 24 hours (in a series of three- to four-hour recordings) at its home farm.

They found that, on average, foals slid 29% of the time when they were getting up. But that percentage varied considerably from farm to farm (0% to 50%) and was probably related to management techniques. They slid less when they had more time to anticipate getting up, the team added. For instance, if a human walked into the stall suddenly, they got up quickly and would be more likely to slip. But if they saw another foal approaching from a distance, they seemed to prepare their movement better and slide less frequently.

Nonetheless, at six months of age, there was a tendency for foals getting up “bovine-style”—like a calf, with their hind end first—to have an association with osteochondrosis of the hock, she said. By 12 months of age, however, the rates had evolved, and foals with osteochondrosis were less likely to slip. This could be because the affected foals were learning to adapt because of pain associated with their condition, VanDierendonck said.

More research is needed to determine whether environmental factors such as footing are causally related to differences in standing behavior and osteochondrosis, the team said.

The study, “Quantitative and qualitative aspects of standing-up behavior and the prevalence of osteochondrosis in Warmblood foals on different farms: could there be a link?” was published in BMC Veterinary Research.