The Effect of Dietary Protein on Body Composition and Renal Function in Geriatric Dogs

Forty healthy geriatric beagles (≥10 years, initially 12.0 kg) were fed a control food during a 30-day pre-feeding period, and then blocked by age, gender, and body fat percentage. Dogs were randomly assigned to 1 of 4 foods (A = Experimental Food, B = Royal Canin Mature Medium Breed, C = Purina Dog Chow Senior, and D = Eukanuba Senior Maintenance) for the 6-month testing period. Blood chemistry, microalbuminuria, and DEXA were evaluated for changes in kidney health and body composition. At Day 180, body weight increased (P < 0.01) in dogs fed Food B and tended (P < 0.07) to increase in dogs fed Food A. No other differences in weight or changes in weight were detected (P > 0.13). Dogs fed Food B and Food D lost lean (P < 0.05) over the 180-day period. Dogs fed Food B also gained fat (P < 0.01) while the other 3 foods maintained fat. In addition, dogs fed Food B gained (P < 0.01) bone mineral content (BMC) while dogs fed Food C lost (P < 0.05) BMC. For kidney function markers, blood creatinine was unaffected by dietary treatment (P > 0.25). Dogs fed Foods B, C, and D had higher (P < 0.03) blood urea nitrogen (BUN) levels than dogs fed Food A. For BUN: creatinine ratio, dogs fed Foods B, C, and D had elevated (P < 0.02) ratios compared to dogs fed Food A. Dogs fed Food D had a greater percentage of animals with reduced kidney function (P < 0.05) as indicated by microalbuminuria analysis compared to dogs fed Food A. In conclusion, geriatric dogs fed experimental Food A with reduced protein/phosphorus showed less progression of kidney disease compared to the other commercial geriatric foods. In addition, dogs fed experimental Food A maintained lean and bone mass compared to other commercial formulations.