Obesity

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Obesity is an excessively high amount of body fat or adipose tissue in relation to lean body mass. The incidence of obesity is increasing at a rapid rate in human beings and in pets. It is now considered the most common nutritional disorder of dogs, with approximately 55% of dogs in the U.S. considered overweight or obese[1].

Obesity in dogs concerns veterinarians because it increases the risk of other diseases, in particular, diabetes mellitus, skin diseases and lameness. Canine obesity is increasingly seen as a pressing animal welfare concern because of the implications of excessive weight gain for chronic diseases and a pet dog’s quality of life[2].

Weight gain is primarily caused by excessive caloric intake and minimal exercise. Evidence continues to emerge that canine health and activity levels in dogs often reflects the health and activity patterns of their owners[3].

It was, until recently, assumed that adipose tissue (fat) was involved only as a store for excess energy and insulation. Recent studies have shown that adipose tissue is also an endocrine organ. Hormones and proteins secreted from adipose cells, termed adipokines, affect systemic appetite levels, inflammatory responses, insulin sensitivity and metabolism. Many genes traditionally associated with lipid, protein and carbohydrate metabolism are not altered in obese versus lean dogs, but genes pertaining to endocannabinoid metabolism, insulin signaling, type II diabetes mellitus and carnitine transport are differentially expressed, suggesting that increasing body weight is responsible for gene-induced hormonal changes[4].

To date, over 50 adipokines have been identified, including leptin, resistin, and adiponectin[5]. Leptin levels increase with obesity and is thought to play a role in satiety. Adipoenectin appears to decrease with obesity and appears to have beneficial effects on the cardiovascular system.

As well as hormonal changes, rapid weight gain (becoming obese versus being obese) is also associated with cardiomegaly[6], impaired T-lymphocyte immune function[7], chronic renal disease[8] and changes in intestinal microbiota[9].

Age-related changes such as cognitive dysfunction syndrome and arthritis require addressing, as these are often aggravated in older obese dogs.

In so far as treatment is required, a low calorie diet and increased activity is essential. Different types of dogs have different exercise requirements to maintain optimal health and these must be assimlated into teh household's daily activity regimen[10].

Morbidly obese dogs may be candidates for suture or staple-based endogastric devices or endogastric mucosal suturing[11].

References

  1. de Godoy MR & Swanson KS (2013) Nutrigenomics: Using gene expression and molecular biology data to understand pet obesity. J Anim Sci Jan 7
  2. Lund EM et al (2006) Prevalence and risk factors for obesity in adult dogs from private US veterinary practices. Intern J Appl Res Vet Med 4:177–186
  3. Courcier EA et al (2010) An epidemiological study of environmental factors associated with canine obesity. J Small Anim Pract 51:362–357
  4. Grant RW et al (2013) Skeletal muscle tissue transcriptome differences in lean and obese female beagle dogs. Anim Genet Mar 12
  5. Lusby, AL & Kirk, CA (2009) Obesity. In Bonagura, JD & Twedt, DC (Eds): Kirk's current veterinary therapy XIV. Saunders Elsevier, St Louis. pp:191
  6. Pelosi A et al (2013) Cardiac effect of short-term experimental weight gain and loss in dogs. Vet Rec 172(6):153
  7. Van de Velde H et al (2013)
  8. Tvarijonaviciute A et al (2013) Effect of weight loss in obese dogs on indicators of renal function or disease. J Vet Intern Med 27(1):31-38
  9. Handl S et al (2013) Faecal microbiota in lean and obese dogs. FEMS Microbiol Ecol Jan 10
  10. Degeling C et al (2012) An investigation of the association between socio-demographic factors, dog-exercise requirements, and the amount of walking dogs receive. Can J Vet Res 76(3):235-240
  11. Légner A et al (2013) Mucosal Excision and Suturing for Obesity and GERD. Surg Innov Feb 18