A 3-year old horned buck of the Toggenburger breed was referred to our
clinic with signs of gynecomastia. Cytogenetic abnormalities could no
t be detected in the karyogram and compared to control animals the buc
k had normal plasma concentrations of testosterone and estradiol but n
ot prolactin. Hyperprolactinemia has been considered the cause of gyne
comastia leaving the semen quality undisturbed.