VN February 2023

Vetnuus | Februarie 2023 40 Introduction Obesity is defined as an accumulation of excessive amounts of adipose tissue in the body and is reported as the most common nutritional disease of dogs in Western countries 1 . The incidence of obesity in dogs and cats worldwide ranges from 22% to 59%, depending on location. Obesity causes harm, morbidity, mortality, reduces life expectancy and negatively impacts on quality of life 2 . Furthermore, obesity is a significant financial burden on pet owners and, as is the case with human medical insurance, may prompt pet health insurance schemes to recognise pet obesity as a risk factor influencing pet insurance premiums. Whilst genetic factors are at play in obesity and breed predispositions, excess calorie intake in relation to calories spent is the overwhelming cause of obesity and can be easily controlled by pet owners. Companion animals are unable to make diet and feeding choices, and pet parents are directly responsible for these choices and consequences. Gonadal status plays a significant role in the development of obesity 3,4,5 . The effects of gonadectomy may be so large that a 30% decrease in energy intake is required to prevent weight gain in ovariectomised Beagles 6 . The situation may be more complex. Current theories propose that LH-hypersecretion following gonadectomy in males and females may be involved in gonadectomy-associated conditions, also termed “LH-disease” 7 . This manuscript briefly discusses how obesity in companion animals leads to functional impairment through metabolic derangements, endocrine disruption and alteration in inflammatory processes, ultimately leading to a myriad of obesity-associated comorbidities. The impact of obesity on fertility and reproduction is also discussed. Recognising obesity and correcting it is good practice and increases both quality and quantity of life for our pets. Obesity assessment and causes The reasons why many well-meaning pet parents overfeed pets may be related to the owner’s lifestyle and own diet, anthropomorphisation of animals and personal belief system 8 . Therefore, addressing pet obesity may be challenging for veterinarians to address with their clients if the veterinarian themselves or their client or both may be considered overweight. Additionally, societal norms have increased socially accepted body mass index acceptable mean in man. It is fair to speculate that the same may have happened in companion animals. Obesity in dogs is associated with the number of meals and snacks fed, the feeding of table scraps and the dog’s presence when its owners prepare or eat their own meals. Pet parents look upon breeders as role models that provide guidance and set an example. The norms of breeders regarding body condition scores may also have been influenced by societal norms, as 19 – 26 % of dogs were considered obese at European dog shows 9 . Measurement of obesity (adiposity) in companion animals involves defining body composition. The main conceptual division of importance is between fat mass and lean body mass. Dual-energy X-ray absorptiometry and deuterium oxide dilution are objective means of body fat estimation and showed good correlation to clinical evaluation methods by using the body condition score based on visual observation and palpation 10 . The nine-point body condition score has been universally adopted by the veterinary community for dogs and cats to clearly, simply, quickly and accurately assess their patient’s body condition and communicate the finding with their clients 11, 12, 8 . The pathological importance of obesity As is the case in man, obesity has detrimental effects on the health and longevity of dogs and cats. Diseases reported to be associated with obesity in companion animals are tabulated ( refer to table on the next page ), and some are discussed in more detail 2 . Obesity and adipokines Adipose tissue comprises numerous cell types, including adipocytes, fibroblasts, macrophages, and endothelial cells. Although the primary role of adipose tissue is to store energy in the form of lipids, it is also metabolically active, releasing adipokines which act systemically or locally to influence various metabolic reactions 19 . Adipokines are essential to normal physiologic function and are important in the regulation of diverse biologic processes, including energy balance, glucose and lipidmetabolism, inflammation, immune function, haemostasis, vascular function, and angiogenesis. There are more than 50 known adipokines, with leptin, adiponectin, interleukins (IL), tumour necrosis factor- alpha (TNFa), and interferon-gamma being best studied in animals. Increased fat mass has been implicated in the dysregulation of adipokine production and contributes to various obesity-related metabolic abnormalities 19 . Monocytes andmacrophages in adipose tissue have been identified as important contributors to obesity- related disorders because they are, together with adipocytes and endothelial cells, sources of proinflammatory, procoagulant and acute phase reactant cytokines. The most important cytokines are discussed. Leptin, also known as an anti-obesity hormone 20 , functions to decrease food intake, increase energy expenditure, and modulate glucose and fat metabolism but leptin resistance develops in obesity. Leptin is directly correlated to fat mass and is thus increased in obese animals, and subsequent weight loss leads to decreased leptin. Leptin concentration is considered a biomarker for the degree of obesity in dogs and cats, regardless of breed, sex, and age 21 . Pathological importance of obesity in pet owned dogs and cats and breeding animals - Part 1 By Kurt G.M. De Cramer BVSc MMedVet (Gyn) PhD