Administration of the medication pergolide for the treatment of equine Cushing's Disease or Pituitary Pars Intermedia Dysfunction (PPID) is now permitted by the United States Equestrian Federation (USEF) during competition. As of December 1, 2018, horses can be granted a Therapeutic Use Exemption (TUE) for pergolide, allowing no withdrawal prior to competition. The TUE will be considered by the USEF after a veterinarian submits medical records using the USEF medical records form. Additional details on this USEF policy change can be found at USEF Pergolide Therapeutic Use Exemption Press Release.

PPID affects 20% of the equine population over 15 years of age and geriatric horses in particular. PPID is caused by a benign enlargement of the middle lobe of the pituitary gland, called the pars intermedia, which compresses adjacent structures including the hypothalamus. Characteristic clinical signs of PPID include excessive hair growth (hirsutism) with reduced shedding, polyuria and polydipsia, muscle wasting, immunosuppression and laminitis. 

The endocrinology section of the Cornell Animal Health Diagnostic Center (AHDC) offers several diagnostic options for the diagnosis of PPID, most commonly an ACTH baseline or TRH Response test is used. The TRH response test requires the veterinarian collect a Pre (or baseline) blood specimen into a purple-top (EDTA) tube, then inject TRH intravenously and collect a second EDTA blood specimen exactly 10 minutes after injection. For both the ACTH baseline and TRH response test, EDTA plasma must be separated from the red blood cells within 4 hours of collection. For additional information on proper sample handling for PPID testing at the Cornell AHDC please read AHDC Equine Cushing's Tests.

Contact Dr. Barbara Schanbacher in the AHDC Endocrinology Section with further questions (607) 253-3578.