Effects of Oral Altrenogest on Testicular Parameters, Steroidal Profiles, and Seminal Characteristics in Young Stallions

Altrenogest is being administered to young stallions in racing and performance to decrease sexually aggressive behavior, although the effects on fertility are unknown. In young stallions, treatment with altrenogest significantly decreased sperm output, testicular size, and hormone production. Eight weeks was not sufficient for recovery. Authors’ address: Dept. of Animal Science and Food Technology, Box 42141, Texas Tech University, Lubbock, TX 79409. r 1997 AAEP.