Prevention of Estrus in Queens by Chlormadinone Acetate Implant

Abstract

The effect of subcutaneous implantation of a silicon implant containing 20mg chlormadinoneacetate (CMA)(Doses implanted: 5.3-9.1mg/kg) on the prevention of estrus was investigated in 10 queens. Estrus was completely prevented during 13.4 months at a minimum dose of 5.3mg/kg. At removal of the implant, the ovaries had no functional corpus luteum and all follicles were atretic, and the uterus showed endometrial hypertrophy and proliferated uterine glands. A slight cystic hyperplasia of the endometrium was observed in 3 queens. In 3 queens implanted with CMA prior to the pregnant mere serum gonadotropin (PMSG) treatment, estrus was prevented, whereas ovulation was not prevented in 3 queens implanted with CMA wasafter estrus induction by PMSG.