Investigation of relationships between body weight and age among domestic cats stratified by breed and sex.

OBJECTIVE To evaluate mean body weight (BW) over the lifespan of domestic cats stratified by breed and sex (including reproductive status [neutered vs sexually intact]). ANIMALS 19,015,888 cats. PROCEDURES Electronic medical records from veterinary clinics in the United States and Canada from 1981 to 2016 were collected through links to practice management software programs and anonymized. Age, breed, sex and reproductive status, and BW measurements and measurement dates were recorded. Data were cleaned, and descriptive statistics were determined. Linear regression models were created with data for 8-year-old domestic shorthair, medium hair, and longhair (SML) cats to explore changes in BW over 3 decades (represented by the years 1995, 2005, and 2015). RESULTS 9,886,899 of 19,015,888 (52%) cats had only 1 BW on record. Mean BW for cats of the 4 most common recognized breeds (Siamese, Persian, Himalayan, and Maine Coon Cat) peaked between 6 and 10 years of age and then declined. Mean BW of SML cats peaked at 8 years and was subjectively higher for neutered than for sexually intact cats. Mean BW of neutered 8-year-old SML cats increased between 1995 and 2005 but was steady between 2005 and 2015. CONCLUSIONS AND CLINICAL RELEVANCE The large dataset for this study yielded useful information on mean BW over the lifespan of domestic cats. This could be a basis for BW management discussions during veterinary visits. A low frequency of repeated BW measurements suggested a low frequency of repeated veterinary visits, especially after 1 year of age, making engagement of cat owners in the health of their animals particularly relevant.