The BSAVA recognises obesity as disease in dogs and cats. Obesity fits formal definitions of the term “disease”, for example those of the American Medical Association.1 In companion animals, obesity has a significant adverse effect on health and welfare including: associations with various additional and often concurrent conditions or diseases, reduced life expectancy, functional impairment and poor quality of life. As a result, the BSAVA encourages veterinary surgeons and owners to be very proactive in addressing obesity and its consequences, in order to improve the health and welfare of the pet.
The BSAVA recommends that vets in practice use a one-to-nine (1-9) body condition score (BCS) scale in dogs and cats. Although many different BCS systems have been developed, the 9-unit scale is the most extensively validated and the one recommended by the WSAVA Global Nutrition Panel. Dogs and cats with a BCS of 6 or 7 are “overweight”, whilst those with a BCS of 8 or 9 are classified as having obesity, which is equivalent to at least 30% excess weight. Other complementary methods of illustrating obesity can also be used to help improve client engagement; examples include: simplified condition scoring systems, photographs, and the use of tape measures. Although measuring bodyweight is not a reliable method of determining body composition, it is precise and accurate. Therefore, the use of repeated bodyweight measurements in the same animal can identify small increases in weight that can then prompt early intervention.
For dogs and cats that are already overweight or have obesity, the BSAVA recommends weight management, comprising a period of controlled weight loss and subsequent weight maintenance. The key components of successful weight management include decreasing energy intake whilst ensuring all essential nutrient requirements are met and increasing physical activity, coupled with regular monitoring and support from a veterinary professional. Evidence suggests that purpose-formulated diets improve owner compliance and many weight loss outcomes (e.g. rate of weight loss, percentage weight loss, chances of reaching target weight). At the same time, they reduce the risk of nutrient deficiencies developing during the process, and also decrease the chances that regain of weight will occur after target weight is reached. The intake of additional food items (e.g. food rewards and table scraps) should be minimised to ensure that the overall diet does not become unbalanced. If treats are used, these should be incorporated into the daily food requirement calculation. Although increasing physical activity does not lead to meaningful weight loss in isolation, it is associated with other benefits including minimising loss of muscle.2 Where there are significant health concerns as a result of obesity, refusal by an animal owner to act on weight management advice is a welfare concern and might constitute a breach of the Animal Welfare Act (2006).
Currently, no licenced pharmaceutical agents for weight management in companion animals are available in Europe, and insufficient evidence exists to make any recommendation on the off-label use of drugs licensed for weight loss in people. Although bariatric surgery is the most effective method of weight loss in people with obesity,3 similar techniques are not routinely used clinically in dogs and cats and, therefore, cannot be recommended or be regarded as normal veterinary practice.
The BSAVA emphasises the need for veterinary surgeons to focus on prevention of obesity as well as management. Given that rapid growth is associated with future risk of obesity in both dogs and cats, prevention strategies should start early in life. A monitoring programme of weight and BCS should commence during a puppy’s growth phase, taking account individual breed variability.4 As a minimum, weight and BCS checks should be conducted at least once a year, but more frequently if feasible, with details recorded in the clinical records. More frequent weighing is strongly advised in animals at risk of obesity (e.g. predisposed breeds, neutered animals, and those that have previously been overweight). Such a strategy would often highlight unwanted weight gain, which can then be addressed early in the disease process through adjustments to diet and exercise. Home weighing (for example, using bathroom scales or weighing in a pet carrier with digital luggage scales) is an alternative where an owner is reluctant to bring their pet to the clinic for weight checks.
For the prevention of obesity, a complete and balanced diet should be fed that is appropriate for the life stage and lifestyle. The amount fed should be measured accurately (e.g. using scales) and adjusted according to changes in bodyweight and BCS. Particular care should be taken when feeding high energy diets (i.e. diets designed for working dogs), which would not be a suitable choice for most pet dogs. Given that neutering is a risk factor for weight gain, veterinary professionals should be extra vigilant in monitoring body weight during the two years after neutering.
The BSAVA would encourage veterinary surgeons to hold supportive, non-judgemental conversations with owners of pets who have obesity. Care should be taken when holding conversations about obesity with owners, since this is a highly stigmatised condition and a considerable societal “fat prejudice” exists. Although studies have not yet been undertaken in cats and dogs, evidence in humans suggests that stigmatising people with obesity threatens health and interferes with effective obesity management.5 Therefore, conversations should be empathic, use non-stigmatising terms and, above all else, facilitate the access of pets with obesity to the veterinary care that they need to improve their health and welfare.
In dogs, overweight and obese status is associated with a shorter median lifespan,6,7 poorer quality of life,8,9 various comorbidities,9,10 metabolic derangements11-13 and significant functional impairment (most notably respiratory, cardiovascular and renal).14-16 Overweight status in cats is also associated with comorbidities11,17-19 and metabolic derangements,11,20 but only a obesity (with a BCS of 9) is associated with a shorter lifespan.21 In both species, obesity is a significant financial burden on owners.22
The exact food used for weight management is a matter of choice for the owner, after a discussion with a veterinary professional, with the key priorities being to ensure that it is both safe (i.e. ensuring all essential nutrient requirements are met) and effective. If the dog or cat is in BCS of 6 and being fed a complete and balanced diet, a modest reduction (20% maximum) in intake of their current food might be effective. However, successful weight loss for dogs and cats with a BCS 7 and above usually requires marked energy restriction for a prolonged period,23-25 and feeding a diet designed for maintenance in such circumstances (including those marketed as “light’ diets) can potentially lead to essential nutrient deficiencies.26,27 Nutrient deficiencies are far less likely when a diet is fed that is purpose-formulated for weight loss.28,29 This can either be achieved by feeding a manufactured weight management diet or a home-prepared diet to a recipe formulated by an appropriately-qualified veterinary clinical nutritionist. As well as reducing the risk of nutrient deficiencies, other benefits include decreasing voluntary food intake30,31 and reducing the risk of weight regain after target weight is reached.32
The degree of energy restriction required for successful weight loss, rate of weight loss and duration of the weight loss phase varies amongst individuals. Although rates of weight loss of between 0.5% and 2.0% per week are reported,23 average rates are usually <1% per week in pet dogs and cats.24,25 Marked energy restriction increases the rate of weight loss, but has been associated with a greater loss of muscle mass in cats.33 Furthermore, loss of muscle mass increases as percentage weight loss increases in both cats and dogs.24,25 Therefore, weight loss targets should prioritise health and wellbeing benefits rather than rates or percentages of weight loss. Whilst suitable targets for weight loss are not well defined, modest amounts of weight loss (i.e. 6-9% of existing body weight) can be sufficient to produce measurable benefits to health.34 However, weight management might be unsuitable in some cats and dogs, such as those with another significant life-limiting disease (e.g. metastatic neoplasia, end-stage liver or kidney disease).
1. American Medical Association House of Delegates. Recognition of obesity as a disease. Resolution 420 (A-13). https://www.npr.org/documents/2013/jun/ama-resolution-obesity.pdf?t=1544195051473
2. Vitger AD et al. J Am Vet Med Assoc 2016; 248: 174-182.
3. Colquitt JL et al. Cochrane Database Syst Rev 2014; 8: CD003641. DOI: 10.1002/14651858.CD003641.pub4.
4. Salt C et al. PLOS One 2017. https://doi.org/10.1371/journal.pone.0182064
5. Puhl RM, Heuer CA. Am J Public Health 2010; 100: 1019-1028.
6. Kealy RD, et al. J Am Vet Med Assoc 2002: 220; 1315-1320.
7. Salt C et al. J Vet Intern Med. 2018; 1–11: https://doi.org/10.1111/jvim.15367
8. German AJ et al. Vet J 2012; 192: 428-434.
9. Yam PS, et al. Prev Vet Med 2016; 127: 64-69.
10. Lund EM et al. Int J Appl Res Vet Med 2006; 4: 177-186.
11. German AJ et al. Vet J 2010: 185: 4-9.
12. German AJ et al. Domest Anim Endocrinol 2009; 37: 214-226.
13. Tvarijonaviciute A et al. BMC Vet Res 2012; 8: 147.
14. Tvarijonaviciute A et al. J Vet Intern Med 2013; 27: 31-38.
15. Mosing M et al. Vet J 2013; 198: 367-371.
16. Tropf M et al. J Vet Intern Med 2017; 31: 1000-1007.
17. Scarlett JM et al. J Am Vet Med Assoc 1998; 212: 1725-1731.
18. Lund EM et al. Intern J Appl Res Vet Med 2005; 3:8 8-96.
19. Teng KT et al. J Sm Anim Pract 2018; 59: 603-615.
20. Tvarijonaviciute A et al. Domest Anim Endocrinol 2012; 42: 129-141.
21. Teng KT et al. J Fel Med Surg 2018; 20: 1110-1118.
22. Bomberg E et al. J Comp Pathol 2017; 156: 310-325.
23. Linder DE & Mueller M. Vet Clin N Amer 2014; 44, 789-806.
24. German AJ et al. J Vet Intern Med 2007, 21: 1174-1180.
25. German AJ et al. J Fel Med Surg 2008; 10: 452-459.
26. Linder DE et al. Vet Quart 2012; 32: 123-129.
27. Gaylord L et al. J Sm Anim Pract 2018; 59: 695-703.
28. Linder DE et al. BMC Vet Res 2013; 9: 219.
29. German AJ et al. BMC Vet Res 2015; 11: 253.
30. Weber M et al. J Vet Intern Med 2007; 21;1203-1208.
31. Hours MA et al. BMC Vet Res 2016; 12: 274.
32. German AJ et al. Vet J 2012; 192: 65-70.
33. Butterwick RF, Hawthorne AJ. J Nutr 1998;128: 2771S-2775S.
Marshall WG et al Vet Res Commun 2010; 34: 241-253.
Other statements and resources
Reviewed by members of BSAVA Scientific Committee 2019 with minor update May 2022