Effects of prepubertal gonadectomy on physical and behavioral development in cats.

OBJECTIVE: To determine the effect of prepubertal gonadectomy on physical and behavioral development in cats.

DESIGN: Prospective controlled study of kittens randomly assigned to 3 treatment groups: group 1, neutered at 7 weeks of age; group 2, neutered at 7 months of age; and group 3, sexually intact controls.

ANIMALS: 31 clinically normal male and female kittens.

PROCEDURE: Age at distal radial physeal closure and mature radius length were determined radiographically. Six behavioral characteristics were recorded monthly. At 1 year of age, body weight was recorded and thickness of the falciform ligament was measured from a lateral abdominal radiographic view. Secondary sex characteristics were also examined at 1 year of age.

RESULTS: There were no differences between group-1 and group-2 cats for any of the study variables. Sexually intact cats (group 3) weighted significantly less than group-2 cats and had less falciform fat and earlier distal radial physeal closure than cats of both neutered groups. Group-3 cats manifested greater intraspecies aggression, less affection, and greater development of secondary sex characteristics than neutered cats.

CLINICAL IMPLICATIONS: Neutering cats at 7 weeks of age had similar effects on physical and behavioral development, compared with neutering at the more traditional age of 7 months. These data lend support to the concept of prepubertal gonadectomy, already performed by many animal shelters/humane organizations, as a method of enhancing the effectiveness of pet population control programs.