Effects of neutering on food intake, body weight and body composition in growing female kittens

To understand the effects of neutering on food intake, body weight (BW) and body composition in kittens, data from an unrelated study were subjected to post hoc analysis. A total of twelve pairs of 11-week-old female littermates were randomly assigned to either a neutered group (neutered at 19 weeks old) or an entire group (kept entire) and offered free access to a dry diet until the age of 1 year. Neutered kittens exhibited increased food intake and increased BW after neutering (both P<0.00 001). Food intake (per kg BW) peaked 10 weeks after neutering; the mean intake of neutered kittens was 17 (95% CI 8, 27)% more than entire littermates (P=0.00 014). The intake was then reduced until there was no significant difference between the groups 18 weeks post-neutering. By 52 weeks of age, the neutered kittens were 24 (95% CI 11, 39)% heavier than entire littermates (P<0.0001) with a body condition score (BCS) 16.6 (95% CI 0.9, 34.8)% higher (P=0.0028). Neutered kittens continued to grow significantly fatter after neutering (all P<0.0014), while entire kittens showed no significant change after 18 weeks of age. As neutered kittens consumed similar amounts of energy to their entire littermates from 18 weeks post-neutering, while their BW, BCS and percentage fat continued to increase, we suggest that neutered kittens have a reduced metabolisable energy requirement, and should therefore be fed to maintain an ideal BCS rather than ad libitum. Moreover, to maintain an ideal BCS, entire kittens consumed 93 (95% CI 87, 100)% of their theoretical intake at 26 weeks of age, and 79 (95% CI 72, 87)% at 52 weeks of age, suggesting that the current energy recommendation is inappropriate for these kittens.