Multiple urogenital and ocular anomalies occurring in a litter of guinea pigs

Following an outbreak of proliferative pneumonia in a guinea pig breeding colony and subsequet treatment with Tylan, a litter of guinea pigs was found to have multiple urogenital and ocular anomalies. Subsequent mating of the parents produced no abnormal offspring. Chromosome typing on the litter showed no abnormalities. A review of normal developmental anatomy and reports of similar anomalies was made in order to elucidate the pathogenesis of the multiple anomalies seen. It was concluded that the teratogenic effect occurred after the formation of the masonephros. The teratogen may have been an infectious agent or the drug Tylan.