Obesity, its associated disorders and the role of inflammatory adipokines in companion animals

Obesity is characterised by an expansion of white adipose tissue mass that can lead to adverse health effects, such as decreased longevity, diabetes mellitus, orthopaedic and respiratory disease and neoplasia. Once thought a passive fuel depot, adipose tissue is now recognised as an active endocrine organ that communicates with the brain and peripheral tissues by secreting a wide range of hormones and protein factors, collectively termed adipokines. Examples include leptin, adiponectin, cytokines (tumour necrosis factor-α, interleukin-6), chemokines, acute phase proteins, haemostatic and haemodynamic factors and neurotrophins. Adipokines can influence various body systems, and perturbation of normal endocrine function is thought central to the development of many associated conditions. This review focuses on the medical consequences of obesity in companion animals, assesses the endocrine function of adipose tissue in disease pathogenesis, and highlights the potential role of adipokines as biomarkers of obesity-associated disease.