Effect of prepubertal versus postpubertal castration on sexual and aggressive behavior in male horses

Males horses castrated prepubertally occasionally display stallion-like sexual and aggressive behavior as adults. A retrospective survey of 140 horse owners was undertaken to compare the effectiveness of prepubertal versus postpubertal castration on objectionable sexual and aggressive behavior. Of 94 geldings that had been castrated prepubertally (before 2 years of age), 20% to 30% displayed stallion-like sexual behavior and aggression toward horses, and 5% were aggressive toward people in a stallion-like manner. This occurrence of problem behavior was not significantly different from the occurrence of these behavioral patterns in 46 geldings that had been castrated as stallions (over 3 years of age). When castration was examined as a therapeutic measure to eliminate sexual and aggressive behavior in stallions in which the behavior had become objectionable, it was found that the operation was effective on sexual behavior and aggression toward people in 60% to 70% of horses and on aggression toward horses in 40% of horses.