Body condition score and triglyceride concentrations and their associations with other markers of energy homeostasis in healthy, non-obese dogs

Serum triglyceride concentrations increase in dogs in overweight condition, which is typically assessed by body condition score (BCS). However, their associations with other markers of energy homeostasis are poorly characterized. The present study aimed to evaluate the associations between both BCS and triglyceride levels and other markers of lipid and glucose metabolism in healthy dogs in overweight condition. 534 overweight, but otherwise healthy, client-owned dogs were included. Serum concentrations of cholesterol, free fatty acids, triglycerides, insulin, glucose and fructosamine were measured. Dogs were assigned to lean (BCS: 3-5) or overweight (BCS: 6-7) categories, and linear models were used to assess the differences between BCS categories and the associations between triglycerides and the other variables, correcting for the effect of breed. Globally, "overweight" dogs had greater serum cholesterol (95% CI: 5.3-6.2 mmol/L or 205-237 mg/dL versus 5.1-5.4 mmol/L or 198-210 mg/dl, P = .003), insulin (95% CI: 17.5-22.1 U/ml versus 16.7-18.0 U/ml, P = .036) and were older (95% CI: 4.0-5.3 versus 3.4-3.7 years, P = .002) than lean dogs. Triglyceride concentrations were positively associated with fructosamine (r2 = 0.31, P = .001), cholesterol (r2 = 0.25, P < .001), insulin (r2 = 0.14, P = .003) and glucose (r2 = 0.10, P = .002), and negatively associated with free fatty acids (r2 = 0.11, P < .001). There was no association between triglyceride levels and age. In conclusion, both BCS and triglyceride concentrations were associated with other markers of glucose and lipid metabolism in overweight, but otherwise healthy dogs. Triglyceride concentrations were associated with an increase in insulin and fructosamine that might reflect an early-phase impairment in glucose tolerance which, surprisingly, was concurrent with lower basal free fatty acids.