Obesity in small animalsadvances in biomarkers and its relationship with human obesity

Resum

The objectives of this thesis were to increase the knowledge in biomarkers of obesity in dogs such as C-reactive protein (CRP), adiponectin (ADP), glucose, fructosamine and insulin. In addition, the relationship with human obesity around European countries was assessed. To carry out the CRP study, an analytical validation of a commercially available heterologous immunoassay for automated measurements of canine CRP and compare it with three different homologous immunoassays were performed. In addition, its capability to detect inflammation in canine serum and the variation of CRP measurements using individual or pooled samples for validation purposes was assessed. ADP was investigate by developing a high-sensitive assay to measure this protein in saliva and serum of dogs with obesity and leishmaniosis. In addition, a specific protease digestion technique for ADP isomers isolation in dog serum was accomplished. The glucose homeostasis biomarkers in dog saliva were studied through the validation of automated assays for glucose and fructosamine measurements and an ELISA assay for insulin determination. The assays were employed to assess the changes in saliva of dogs after an experimental glucose administration. Finally, to investigate dog owner perceptions about obesity among themselves and their dogs, and identify common factors and possible social, environmental and economic drivers that could relate to obesity in dog-owners and their dogs, a cross-sectional questionnaire-based study was performed across multiple European countries. The results of the articles compounding this thesis indicate that the heterologous assay for CRP determination showed similar results to the homologous assays in the analytical evaluation that indicated that the assay was precise and accurate. In addition, it was able to detect higher CRP values in dogs with inflammatory conditions compared to healthy dogs. Moreover, the new ultrasensitive method was able of measure ADP in serum and saliva of dogs with high repeatability and sensitivity, adding a limit of quantification lower than commercially available ELISAs. ADP concentrations determined by this assay were decreased in obese dogs compared with lean dogs and correlation between serum and saliva were observed. In addition, dogs with leishmaniosis presented decrease levels of ADP. The use of selective protease digestion detected the different ADP isomers in canine serum and the HMW and LMW forms were increased in Beagles dogs after an experimental weight loss program. Finally, the common factors associated with obesity in owners and their dogs identified by the obesity-case study were age, gender and owners' attitudes to diet and physical activity. Remarking that dog-owners who did not consider obesity to be a disease were more likely to have obese dogs