Abstract

The treatment of normal male dogs with a depot preparation of medroxyprogesterone acetate (4 mg/kg) for 7 weeks reduced peripheral testosterone levels by 58%. No effects on testicular size and consistency, semen quality or libido were found.

PIP:

The effects of MPA (medroxyprogesterone acetate) on the reproductive processes in dogs was investigated to determine its therapeutic potential for future breeding of dogs. Testicular size and consistency, semen quality, libido and peripheral plasma testosterone levels were also assessed. 8 mature dogs of mixed sheep-dog ancestry 10-17 kg body weight were studied. Semen quality was assessed by Galloway's method. Semen was collected via manual stimulation of the penis in the presence of an oestrous bitch. Each of the characters except testicular size was studied before treatment (Test 1). The characters were reassessed 7 weeks later (Test 2). 4 mg/kg MPA were injected in 4 dogs. Wilcoxon's 2-sample test was used to test significant differences. There were no significant differences observed between testicular size, testicular consistency, or any other semen characteristics (p0.05). At Test 2, time from introduction to an oestrous bitch to first mount was significantly reduced (p0.05); there were no significant differences between the groups (p0.05) at this test. MPA treatment significantly and markedly reduced mean plasma testosterone levels. Normal dogs as used in this experiment do not seem to provide a good model for the assesment of efficacy of substances to reduce excessive or aberrant sexual behavior in dogs.