PPID DIAGNOSTIC TECHNIQUE ADVANCES

Year-round diagnosis of pituitary pars intermedia dysfunction (PPID, also known as Cushing’s) just got easier, thanks to the joint efforts of equine researchers in England and mathematicians in Australia.

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Caused by an enlarged and overactive pituitary gland, PPID is characterized by overproduction of adrenocorticotrophic hormone (ACTH). This hormonal imbalance can lead to a slew of complications, including a long-haired, slow-to-shed coat, muscle weakness and compromised immunity. PPID also increases susceptibility to laminitis. Although typically found in horses 15 years old or older, PPID can also occur earlier in life.

PPID diagnosis usually requires tests that measure the ACTH levels in a horse’s blood. These levels naturally fluctuate by season, however, which can make interpreting results difficult. “The pituitary gland controls several processes that are seasonally variable---such as reproductive hormones,” explains Andy E. Durham BVSc, MRCVS, of the Liphook Equine Hospital in England. “Exactly why the pars intermedia (a specific areas of the pituitary gland) changes activity through the year is not understood. It might be that this is a process that has simply remained during evolution and is of no value or benefit to the horse.”