Equine Pituitary Pars Intermedia Dysfunction (Equine Cushing’s Syndrome) Cheyanne Eaton and Karl Hoopes, DVM
Equine Pituitary Pars Intermedia Dysfunction Pituitary pars intermedia dysfunction (PPID), also known as equine Cushing’s disease, is an endocrine disorder that affects a horse’s pituitary gland. This disease is particularly common in older animals, affecting up to 25% of horses aged 15 years or older. Common symptoms of PPID include delayed coat shedding, long curly hair, pendulous abdomen, muscle wasting, increased thirst and urination, insulin dysregulation, infertility, and lethargy. Involving a veterinarian early in the diagnosis and treatment of PPID will greatly enhance the horse’s welfare and longevity. A veterinarian diagnoses PPID by observing symptoms and testing blood. Treatments for this disease include medicinal intervention and dietary changes. Early disease recognition and treatment make it more manageable.
Disease Process
Quick Facts Pituitary pars intermedia dysfunction (PPID) is an endocrine disorder in horses. PPID affects up to 25% of older horses over age 15. A veterinarian can diagnose PPID through a hands-on exam and testing adrenocorticotropic hormone (ACTH) levels in the blood. Common PPID symptoms include delayed shedding, increased urination, increased water intake, immunosuppression, weight loss, muscle wasting, laminitis, and lethargy. Treatment includes medication and dietary management.
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The equine pituitary gland is located at the base of the brain where it is separated by a sheet of dura mater (a thick, fibrous membrane that • covers the brain and spinal cord). The pituitary gland is composed of four lobes. Each lobe produces hormones that regulate various bodily • functions. In horses with PPID, the regulatory processes within the pars intermedia (one of the four lobes of the pituitary gland) become disrupted (Figure 1). The pars intermedia in horses affected by PPID loses dopamine input due to the degeneration of dopamine-producing neurons in the hypothalamus. Without adequate dopamine, which 1