Metabolic and hormonal response to a feed-challenge test in lean and overweight dogs

Obesity and obesity-related metabolic dysfunctions are increasing in humans as well as in dogs.1,2 Obese dogs become affected by chronic diseases at young age, have a decreased quality of life and a shorter life-span.3 The aim of the study was to describe the metabolic and hormonal response to a feed-challenge test in lean and overweight dogs. Twenty-eight healthy intact male Labrador retrievers aged 5.2 ± 1.5 years with varying body condition score (BCS, scale 1-9) were included. Twelve dogs were classified as lean (BCS 4-5), ten as slightly overweight (BCS 6) and six as overweight (BCS 6.5-8). An overnight fasting period and blood sample collection was followed by a high fat meal. After food intake, blood samples were collected hourly for four hours. A Glucagon ELISA was validated for use in dogs. The assigned BCS was supported by positive association with serum leptin concentrations. Postprandial triglyceride concentration was significantly higher in the overweight group. A tendency to higher cholesterol concentration was seen in the overweight group but cholesterol was not affected by food intake. Glucagon concentration rose after food intake and resembled the response seen in humans after a mixed meal. Glucose and insulin concentrations followed the same pattern while free fatty acids had declined one hour after the meal. In this study, the metabolic and hormonal response to a high fat meal was similar between lean and slightly overweight dogs, whereas the response of overweight dogs differed. Studies on the health significance of postprandial hypertriglyceridemia in dogs are warranted.