A Systematic Review and Meta-Analysis of Serum Adiponectin Measurements in the Framework of Dog Obesity

SIMPLE SUMMARY: Adiponectin is a molecule with biological activity that is closely linked with obesity and obesity-related problems. Despite some literature publications, there is a lack of consensus about how adiponectin changes in canine obesity. Therefore, a meta-analysis is performed here to assess the global performance of adiponectin concentrations in terms of obesity in dogs. After considering 20 different studies, including a total sample size of 366 dogs with obesity and 349 normal weight dogs, the meta-analysis indicates that adiponectin in serum is lower in obese dogs compared with normal weight dogs and increases after weight loss programs. ABSTRACT: Adiponectin is an abundant plasma protein that is closely related to obesity and obesity-related pathologies. The molecule can be found in three different isoforms, each with different biological activities. Studies on canine obesity have suggested that adiponectin concentrations are decreased in obesity; however, no canine meta-analyses have been performed that feature all the required data. The aim of this study is to perform a systematic review and meta-analysis of studies that pertain to total and high molecular weight (HMW) adiponectin in relation to canine obesity. From 20 different studies, a total of 366 dogs with obesity and 349 normal weight dogs are included in the meta-analysis. Client-owned dogs were most represented, accounting for 54.3% of the dogs used, while experimental dogs enrolled in the studies made up the remaining 45.7%. The concentrations of total adiponectin in dogs with obesity were significantly lower compared with normal weight dogs. Additionally, adiponectin concentrations were significantly higher in dogs after a successful weight loss protocol compared to the start of the protocol and were significantly lower in dogs after gaining weight. In conclusion, although caution should be taken due to the relatively low number of studies that exist and the high heterogeneity between them, this meta-analysis indicates that adiponectin is decreased in obese dogs.