How owners manage pastures and seasonal consumption of grass carbohydrates can significantly affect horses with Cushing's disease, according to researchers from the University of Tennessee's College of Veterinary Medicine. And, while the researchers' study did not focus directly on laminitis, owners could avoid laminitis by heeding its findings.

Horses with Cushing's disease, a relatively common hormonal disturbance in older animals, tend to be susceptible to other ailments, but the most life-threatening is laminitis, according to Nicholas Frank, DVM, PhD, Dipl. ACVIM, lead author of the study on the effects of seasonal grazing on Cushing's horses. Laminitis is inflammation of the laminae, which connect the hoof wall to the coffin bone inside the hoof.

"Laminitis is the worst complication and the most common reason a horse with Cushing's would be euthanized," said Frank. He noted there are several theories on why horses with Cushing's could be predisposed to laminitis. Cushing’s could weaken the hoof structure, and it could affect delivery of blood and nutrients to the foot, possibly making hooves more susceptible. Researchers also theorize that insulin resistance (IR) is more likely to occur among Cushing's horses, making them more likely to develop laminitis, Frank said.

The researchers examined the glucose and insulin levels of eight horses with a Cushing's diagnosis and nine control group horses when turned out to pasture and again after they were confined to stalls over the course of a year. Investigators also examined carbohydrate levels of the pasture grasses to determine if there was a seasonal correlation with insulin and glucose levels in the study population