Effect of Pergolide Therapy on Semen Parameters in a Stallion With Pituitary Pars Intermedia Dysfunction

Abstract

A 23 year-old Warmblood stallion with pituitary pars intermedia dysfunction (PPID) was treated with 0.002 mg/kg body weight pergolide orally once a day, starting in July. Semen collections during five consecutive days each were performed before starting and at 90 days after initiation of the therapy in order to assess the effect of the therapy on semen volume, concentration, total sperm count, motility and viability. The only changes observed were lowered semen volume compensated by increased semen density resulting in an equal total sperm count. Possible causes for these observations include altered prolactin levels, the influence of season, or pergolide acting directly on the ejaculation process. This case report provides first evidence, that pergolide therapy in PPID may alter semen parameters, but these changes are unlikely to affect fertility. However this observation in a single individual must be confirmed with experiments on multiple stallions.