Efficacy, safety and reversibility of bisdiamine as a male contraceptive in cats.

Bisdiamines have potential as a male contraceptive due to their ability to arrest spermatogenesis. The bisdiamine WIN 18,446, has proven safe and effective in grey wolves, domestic dogs, rats, and humans, but the unique drug metabolism of cats make extrapolation to felids inappropriate. This study used domestic cats to test the efficacy and safety of bisdiamines in felids. Five domestic cats were given 150mg/kg WIN 18,446, mixed in food daily from Day 0 to Day 76, and were monitored until Day 152. Cats were observed daily and weighed weekly. Physical exam, hematology, clinical chemistry and urinalysis were conducted on Days 0, 7, 14, 28, 76, and 152 of the trial. Serum testosterone concentrations were measured on Days 0, 75, and 152. Unilateral orchectomies were performed on Days 76 and 152, and testes evaluated by histopathology. Spermatogenic arrest occurred in all cats during the treatment period, but normal spermatogenesis was restored by Day 152. Serum testosterone concentrations were lower on Day 76 (2.62 +/- 2.5 ng/ml; P < 0.01) than Day 0 (7.3 +/- 1.0 ng/ml), but returned to pre-treatment concentrations in four of five cats by Day 152 (6.16 +/- 2.1 ng/ml; P >0.05). Clinical pathology parameters remained within reference ranges during the treatment period; however, urine calcium oxalate crystals were noted only during treatment in three cats. Bisdiamine (WIN 18,446) was a safe and effective contraceptive for male cats, but testosterone concentrations decreased during treatment.