Carlos Gomez-Fernandez-Blanco ^1* DOMINIQUE PEETERS ¹ Frederic Farnir ² Katja Höglund ³ Vassiliki Gouni ^4,5 Maria Wiberg ⁶ Jakob Lundgren Willesen ⁷ Sofia Hanås ^3,8 Kathleen Mcentee ^10,9 Laurent Tiret ^4,5 Jens Häggström ³ Hannes Lohi ¹¹ Valérie Chetboul ^4,5 Merete Fredholm ¹² Eija Seppälä ¹¹ Anne-Sophie Lequarré ⁹ Alexander German ¹³ Anne- Christine Merveille ¹

• ¹ Department of Clinical Sciences, College of Veterinary Medicine, University of Liège, Liège, Belgium
• ² Fundamental and Applied Research for Animals and Health Research Unit, Faculty of Veterinary Medicine, University of Liege, Liege, Liege, Belgium
• ³ Swedish University of Agricultural Sciences, Uppsala, Uppsala, Sweden
• ⁴ INSERM U955 Institut Mondor de Recherche Biomédicale (IMRB), Créteil, France
• ⁵ INRA École Nationale Vétérinaire d'Alfort (ENVA), Maisons-Alfort, Île-de-France, France
• ⁶ Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Uusimaa, Finland
• ⁷ Department of Veterinary Clinical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Capital Region of Denmark, Denmark
• ⁸ Specialist Animal Hospital Stromsholm, Strömsholm, Sweden
• ⁹ Department of Equine Clinical Sciences, Faculty of Veterinary Medicine, University of Liege, Liège, Liège, Belgium
• ¹⁰ Faculté de médecine, Université libre de Bruxelles, Brussels, Belgium
• ¹¹ Department of Medical and Clinical Genetics, Faculty of Medicine, University of Helsinki, Helsinki, Uusimaa, Finland
• ¹² Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Capital Region of Denmark, Denmark
• ¹³ Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, North West England, United Kingdom

Serum triglyceride concentrations increase in dogs with obesity, which is typically assessed by body condition score (BCS), however little is known about changes that take place in non-obese dogs in overweight condition. Further, the associations of triglyceride levels with other markers of energy homeostasis are poorly characterized in healthy animals. The present study aimed to evaluate associations between both BCS and triglyceride concentrations with other markers of lipid and glucose metabolism in healthy, non-obese dogs, as well as to assess whether these markers change significantly in non-obese dogs with overweight as compared to their lean counterparts. Serum concentrations of cholesterol, free fatty acids, triglycerides, insulin, glucose and fructosamine were measured in 532 healthy, client-owned dogs, assigned either to ‘lean’ (BCS: 3-5) or ‘overweight’ (BCS: 6-7) categories. Generalized linear mixed models were used to assess associations between BCS categories, triglyceride concentrations and other variables, correcting for the effect of breed. Compared with lean dogs, overweight dogs had a greater serum cholesterol concentration (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=0.0032), insulin concentration (95% CI: 17.5-22.1 µU/ml versus 16.7-18.0 µU/ml, P=0.0374) and were older (95% CI: 4.0-5.3 versus 3.4-3.7 years, P=0.0005). Triglyceride concentrations were positively associated with fructosamine (r2=0.31, P=0.0012), cholesterol (r2=0.25, P<0.0001), insulin (r2=0.14, P=0.0030) and glucose (r2= .10, P=0.0014) concentrations, and negatively associated with free fatty acid concentrations (r2=0.11, P<0.0001). However, there was no association between triglyceride concentrations and age. In conclusion, both BCS and triglyceride concentrations were associated with other markers of glucose and lipid metabolism in non-obese healthy dogs, among which those with overweight showed metabolic changes as compared to their lean counterparts. Triglyceride concentrations were associated with an increase in insulin and fructosamine concentrations that might reflect an early-phase impairment in glucose tolerance which, surprisingly, was concurrent with lower basal free fatty acid concentrations.