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Effect of Early Neutering on Physeal Closure in Cats

Clinician's Brief (Capsule)


|July 2014

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Androgens and estrogens accelerate physeal closure by allowing calcium deposition at the physes. In cats, physes have been shown to close at 4–9 months of age, but studies have shown delayed closure secondary to early neutering. This retrospective study sought to further establish this database, focusing on several pelvic limb physes, with a hypothesis that male and female neutered cats would have open physes at a later age than do intact cats.

Pelvic and femoral radiographs (n = 783) of cats were evaluated for physeal closure at the greater trochanter, proximal femur, distal femur, and proximal tibia. Date of birth, gender, breed, and neuter status were recorded, but age at time of neuter was not available.

The only significant differences noted were later closure in neutered males, as compared with intact males, at the greater trochanter, distal femur, and tibial tuberosity. No significant differences were found in female cats at any physis. Clinical consequences should be further evaluated.


Slipped femoral capital epiphysis (SFCE) remains an interesting yet elusive topic; the body of evidence in domestic animals would suggest that removal of sex steroids by gonadectomy delays physeal closure. As with SFCE in children, other genetic and environmental features play a role.

This study provided findings that varied based on the physis examined. Interestingly, no difference was noted between gender or gonadectomy for the main area of interest in cats, the proximal femoral physis, based on radiographic review at 9 months of age. As only small subsets of each gender and gonad status were compared, the power of the statistical analysis was limited. Clearly, more work is needed to understand the intertwined relationship between sex hormones and physeal closure as it pertains to SFCE.—Jason Bleedorn, DVM, DACVS


Effect of neutering and breed on femoral and tibial physeal closure times in male and female domestic cats. Perry KL, Fordham A, Arthurs GI. J FELINE MED SURG 16:149-156, 2014.

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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