Confused about Cushing’s Disease/PPID testing and if your horse needs it? No fear! Here is a quick summary of testing options and recommendations.
PPID stands for Pituitary Pars Intermedia Dysfunction and is also known as equine Cushing’s disease. In a nutshell, it is an age-related condition of glands in the brain (specifically the pituitary gland) that leads to the production of abnormal levels of hormones.
PPID is diagnosed by measuring hormone levels in the blood. ACTH is the hormone we use as a marker for pituitary function in regard to PPID. Insulin is also measured to screen for insulin resistance/dysfunction, a common consequence of PPID.
ACTH can be measured two ways. Basal/baseline testing is when we take a single blood sample to measure levels present under normal conditions. This is the recommended testing level in fall months and is also often performed to check levels on horses who are receiving treatment for PPID.
TRH stimulation test is recommended for diagnosing PPID in the non-fall months. This consists of taking two blood samples, one before and one 10 minutes after giving a medication called TRH. In horses with PPID, the administration of TRH will cause the ACTH levels in the second blood sample to be significantly elevated.
PPID testing is recommended in geriatric horses (~14+ years old), especially those with a history of laminitis, recurrent infections, non-healing wounds or soft tissue injuries, muscle loss, abnormal body fat distribution, reduced performance, drinking or urinating more than normal, or have an abnormal haircoat. Does that seem like a long, varied list of clinical signs? That’s because PPID presents differently in each horse depending on severity of the disease and how their pituitary function is changing.
PPID testing can be performed at the same time as your horse’s spring vaccine/wellness appointment! Just let the front office know you’re interested in testing while scheduling the appointment so they can discuss feeding instructions for the day of testing.
Get more information about the management of equine metabolic disorders from the Equine Endocrinology Group.