All-season Cushing’s tests

You may have been told that testing for pituitary pars intermedia dysfunction (PPID, also known as Cushing’s) wasn’t reliable in the fall months. That’s no longer true.

A horse with PPID has a malfunctioning pituitary gland, which secretes excess levels of the hormone adrenocorticotropin (ACTH). This, in turn, triggers the adrenal gland to increase the production of cortisol. The resulting hormonal imbalances lead to the hallmarks of Cushing’s: a long, shaggy hair coat, loss of muscle mass, laminitis and susceptibility to infection.

Seasonal fluctuations in hormone levels once made testing for PPID difficult in the late summer and early fall, but research has led to a better understanding of normal reference values. Veterinarians can now interpret results from blood tests done in any season.

The medication pergolide successfully controls PPID in most horses. If you suspect your horse may have the condition, there’s no need to delay testing and, if necessary, to begin treatment as soon as possible.

This article first appeared in the September 2017 issue of EQUUS (Volume #480)

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