Observations on the effects of ICI compound 33828 (methallibure) on semen production in dogs.

THE CHEMICAL CONTROL of spermatogenesis in man and animals has been investigated in recent years as one of the methods for controlling the human population. The compounds which produce inhibitory effects on the testes fall into two general categories: (1) those which inhibit spermatogenesis only, without apparent influence on the endocrine function of the testes, and (2) those which inhibit both germinal and Leydig cell function by suppressing the secretion of the gonadotrophic hormones. In addition to steroids, various non-steroidal agents demonstrate this latter effect. Unpublished data (1) has illustrated that the non-steroidal ICI Compound 338281 (methallibure) when administered to dogs at the levels of 20, 50 and 80 mg./kg./day, inhibited spermatogenesis at the primary spermatocyte stage. The compound is considered to be a pituitary inhibitor. In addition to affecting spermatogenesis, the compound, when administered at high levels, has caused vomition and bloody diarrhea in dogs. This lasted for two to four days after initiation of treatment. The work reported in this study was undertaken to observe the effect of low levels of ICI Compound 33828 on the quality and production of dog semen, and any other effects.