Biology of Reproduction, Vol 1, 41-48, Copyright © 1969 by Society for the Study of Reproduction

Methyl Testosterone-induced Female Pseudohermaphroditism in Dogs

¹ Department of Animal Science, Cornell University, Ithaca, New York; and Department of Large Animal Medicine, Obstetrics and Surgery, New York State Veterinary College, Ithaca, New York 14850

Female dogs were fed methyl testosterone (150 µg/kg body weight/day) alone or, with one of two concentrations of dieldrin (1.5 or 15.0 µg/kg body weight/day) in a meal type diet. The feeding of the chemicals began on the day of first mating and was continued through pregnancy, parturition, lactation and for 9 months thereafter. A total of 87 pups were born to 14 females fed methyl testosterone whether dieldrin was fed or not. Forty-two of the 87 offspring were intersexes whereas the remaining 45 were normal males. Nine "intersex" pups and nine of their apparently normal male litter mates from five litters were necropsied and their leukocytes were studied for karyotypes. All of the "intersex" pups were genetic females. There was no evidence that dieldrin influenced the number of abnormalities or their anatomical characteristics. The anatomical abnormalities observed are described.