EFFECT OF OVARIOHYSTERECTOMY ON MAINTENANCE ENERGY REQUIREMENT IN CATS

Objective-To determine whether maintenance energy requirement (MER) to maintain stable body weight (BW) is substantially lower for spayed fe male cats than for sexually intact female cats and to assess whether a n equation commonly used to estimate MER would accurately predict oric need in spayed cats. Design-Prospective study. Animals-10 spayed and 5 sham-operated young adult female cats. Procedure-During an acclimati zation period, initial daily food allowance was determined by estimati ng MER as 1.4 X (30 X BW + 70), then adjusted weekly to maintain BW wi thin 200 g of baseline. Ovariohysterectomy (OHE) or sham laparotomy wa s performed at week 7, and the study was continued for 15 additional w eeks (period 1). To correct for a presumptive effect of continued musc uloskeletal growth that resulted in some cats becoming unacceptably th in during period 1, the study was repeated over an additional 10 weeks (period 2), using a new estimate of MER calculated from BW measured a fter reestablishing normal body condition. Results-Substantial restric tion in food allowance was necessary to prevent BW gain in the OHE gro up during both periods. Caloric intake of spayed cats in dietary balan ce was significantly lower than that of control cats at the end of eac h study period. Sexually intact cats appeared to self-regulate food in take, whereas spayed cats tended to eat all food available to them. Si gnificant differences were not detected between OHE and control groups in observations of physical activity before or after surgery. The equ ation used to predict caloric needs overestimated the apparent MER for spayed and sexually intact cats. Clinical Implications-Ad libitum fee ding of spayed cats may be inadvisable, and careful monitoring of food allowance, relative to body condition, is suggested to prevent excess ive weight gain.