effects of dexamethasone and prednisolone on pituitary and ovarian function in the mare

Summary Reasons for performing study: Persistent mating induced endometritis is among the most common causes of infertility in the mare. Recently, improved pregnancy rates have been reported when corticosteroids were administered to ‘problem mares’ specifically, to modulate the post mating inflammatory response; however, the effect of treatment on pituitary and ovarian function requires further study. Objectives: To evaluate the effects of prolonged treatment with glucocorticoids on pituitary and ovarian function. Methods: Eighteen cycling Quarter Horse mares in early oestrus were assigned randomly to one of 3 treatment groups: dexamethasone 0.05 mg/kg bwt i.v. twice a day, prednisolone 0.5 mg/kg per os twice a day, or placebo for 5 days. Mares were examined by ultrasound daily to evaluate reproductive function. Blood samples were collected daily to measure luteinising hormone (LH), progesterone and cortisol levels. Results: Dexamethasone treatment caused greater (P