This hormone disease can cause diabetes-like syndrome, weight loss, chronic laminitis and a long, shaggy curly hair coat.
By Jennifer Walker in America’s Horse | January 12, 2011
Autumn’s chill does not just mean your horse will grow a longer coat. It can also mean he’ll have higher natural levels of the hormone plasma adrenocorticotropin, which, in conjunction with other factors, can lead to flare-ups of laminitis.
Cushing’s is a hormone disease that is the result of a pituitary gland tumor. The disease causes a variety of problems that can include diabetes-like syndrome; weight loss; chronic laminitis; and a long, shaggy, curly hair coat that fails to shed. There is no cure, but in some cases the signs can be lessened by the administration of medications to suppress overproduction of certain hormones and stimulate production of that neurotransmitter dopamine, according to the American Association of Equine Practitioners, an alliance partner of the American Quarter Horse Association.
Veterinarians recommend that owners test, monitor and manage horses with metabolic problems carefully during this time of year, realizing that ACTH levels and their effects can be horse dependent.
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Since high levels of ACTH can be indicative of Cushing’s disease, also called pituitary pars intermedia dysfunction, veterinarians often use that parameter as a test for the disease. However, the spikes in ACTH occur even in healthy horses from September until January and can cause false positives.
“We generally recommend not testing (for Cushing’s diagnostic purposes) during these months,” says Dr. Anne Wooldridge, assistant professor of equine medicine at Auburn University. Instead, she recommends that owners of older horses that exhibit any of the classic signs of Cushing’s during the fall months work with their veterinarians to determine whether they should test or treat horses until diagnoses can be confirmed.
Clinical signs of Cushing’s can include:
• Excessive hair growth
• Muscle wasting
• Abnormal fat deposition
Horses with Cushing’s disease are at particular risk of laminitis, but the condition can develop in normal horses as well. Beth Kennalley is with The Founder Rehab Ranch, a rescue organization near Clayton, California, that focuses on horses with laminitis and metabolic disorders. Beth says she avoids feeding hay that could cause a spike in ACTH levels, and she recommends having every batch of hay tested.
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“We shoot for less than 10 percent total sugar plus starch – nonstructural carbohydrates,” she says. If this is not feasible, soaking hay in cold water for an hour might remove up to one third of the sugar.
“Older horses and those starting to develop Cushing’s typically have higher rises (in hormone levels), which can lead to unexplained episodes of laminitis in the fall,” says Dr. Eleanor Kellon, co-owner of the Yahoo Equine Cushing’s and Insulin Resistance Group. “This may occur for years before the horse develops the classical coat changes or tests positive at other times of the year. I recommend treating these horses with pergolide (pergolide mesylate) at least during this high-risk period. Diet control alone won’t be enough.”