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Obesity in companion animals: reviewing the recent publications

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01 November 2011, at 12:00am

CATHERINE-MARY HOWARD believes veterinary professionals should play a key role in helping to change the mindset of owners through education on obesity recognition, diet and exercise

OBESITY: this is a disease that must be taken seriously! Achieving weight loss in overweight dogs and cats can be a real uphill struggle but in theory it should be a piece of cake (or maybe not if weight loss is the ultimate goal!). After all, we can easily control what goes into the food bowl of a dog or cat and if it is as simple as calories consumed versus calories expended, then surely we just need to reduce the number of calories our patients are offered and increase their exercise levels? Obviously, it isn’t as easy as that, otherwise we wouldn’t be seeing the massive increase in numbers of overweight and obese pets that can’t be missed within the UK. So where are we going wrong? Personally, I believe the first issue is actually getting the owner to appreciate that his or her animal is carrying too much weight. Show an owner a picture of an underweight dog or cat and he or she will be the first to tell you that the animal in question looks sick. However, show a picture of an overweight pet and the most common reaction you will get is one that the pet looks “cute” or “cuddly” (Figures 1-4). In fact, 80% of pet owners in the UK believe their pet is just the right weight, despite 30-60% of the pet population in the UK being overweight depending on which studies you read.15 This point just goes to reinforce the fact that pet owners don’t understand what normal looks like for their pets. So how can we help with this tricky situation? As veterinary professionals, our first duty of care is to inform and educate the owners about the serious consequences of obesity for their pets – it is a disease condition after all, just like any other illness they would expect our advice on. Therefore, we need to advise on what is normal, how to body condition score and how to notice and deal  with inappropriate feeding patterns and behaviours. Secondly, the next thing we mustn’t neglect is to advise an optimal exercise protocol for the pet in question, which may need to be changed significantly as the pet loses more and more weight and becomes more tolerant of higher exercise levels. Finally, if obesity is already an issue, we need to be recommending a diet that can help reduce some of the unwanted side effects that go hand in hand with dieting and weight loss. These side effects include: small feeding volumes, hunger, poor coat condition and begging behaviours that pets often show during weight loss. An excellent solution to the dietary issues is to use a high protein and high fibre diet, designed specifically for weight loss in companion animals, and there is a lot of recent research to back the use of diets of this sort. 

The way forward

Recent publications have reported many benefits in using a high protein and high fibre (HPHF) diet in obese dogs and cats to promote weight loss, over a diet that is either solely high in protein or high in fibre.1,2,3 The main benefit found in both dogs and cats when a HPHF diet is used during weight loss, is improved satiety when compared to either a high protein (HP) or a high fibre (HF) diet on their own. It is important to recognise that different types of fibre have very different effects on satiety; for example, psyllium, one of the fibre types used in the HPHF diets (amongst others), has been shown to delay gastric emptying in dogs6 and humans5 and is hence thought to improve satiety in this way. Other insoluble fibres such as cellulose have fewer benefits on satiety. As vets and vet nurses, we are all very aware that weight gain and obesity are common in dogs and cats and predispose them to a variety of diseases and decreased longevity.4 The detrimental effects seen in obese dogs include orthopaedic disease, respiratory disease and urinary tract disorders.4,12,13 Interestingly, and more recently, insulin resistance has been confirmed in obese dogs, thought to be linked to TNFα production by the white adipose tissue, as is seen in obese humans. Significant improvement in resistance to insulin has been shown following weight loss in these dogs.14 Other insightful new findings reveal that levels of acute-phase proteins, such as haptoglobin and C-reactive protein, reduce significantly following weightloss in dogs, suggesting that canine obesity may also be associated with a potentially detrimental subclinical inflammatory state.14 The revelations discussed in the paragraph above only reinforce the fact that weight loss should be taken more seriously in overweight pets. Experimentally, it has been shown that it is relatively easy to induce weight loss in overweight and obese animals but in practice this can be much more difficult.8 A major hurdle is the fact that energy restriction causes hunger, leading to increased begging and scavenging activity by the pet, which can put major strains on the relationships between owner and pet. Strained relationships often lead to owner non-compliance or complete withdrawal from the weight-loss regime, something which would never become an issue in experimental models. Therefore, any advances that may result in an improvement in satiety during weight loss should be welcomed by veterinary practitioners with open arms! Concerns that have been reported over the use of any high fibre diets for weight loss in dogs and cats include the potential for reduced digestibility, particularly of the protein portion of the dietary ration. However, recent studies1 report that the use of high quality HPHF therapeutic diets readily available to veterinary practitioners do not result in reduced digestibility and it is speculated that this is due to the fact that the protein used is of such high quality, the index for indigestible protein is extremely low. Having such a low level of indigestible protein is of major benefit, because it means satiety is maintained, whilst the benefit of highly digestible protein levels minimise the risk of lean tissue loss during weight loss, instead promoting the beneficial loss of adipose tissue. When using a HPHF diet for weight loss, other benefits include a faster (but still safe) rate of weight loss in dogs3 alongside no deleterious difference in palatability of the diets in dogs1 and cats7. In cats, the way some therapeutic HPHF diets are packaged (as is readily available in general practice) has also been shown to greatly reduce the inconvenience the owners are put through. In terms of packaging, the manufacturers simply pre-measure and pre-pack the dry feline HPHF ration in aliquots for cats where either a whole or half sachet is used per meal, thereby ensuring exact compliance with measuring the quantity of diet and avoiding the potential for inaccuracies and incompliance.2 Owners have reported that this is preferable, by far, to having to use a measuring cup and/or scales every day to get the quantities correct.2 

Staying slim once the target is reached 

Regaining weight post-weight-loss is widely reported in humans9 and anyone who has ever tried to lose weight themselves (myself included!) may well be very familiar with the notorious rebound-effect following a period of successful loss! Until recently there was very little information available on this phenomenon in pet animals. Studies in humans show that up to 64% of participants on diet-based weight-loss strategies regain more weight than they originally lose.9 Some very recently published articles show that regain is also an issue in pet dogs following weight reduction10 and that this is thought to be due to the fact that the maintenance energy requirement (MER) of pet dogs decreases significantly after weight-loss.11 The current National Research Council MER recommendation for inactive adult pet dogs is 398-440kJ (95- 105Kcal)/kg 0.75/day, whereas obese pet dogs that maintain their target weight after successful weight-loss have an average daily metabolisable energy intake of 285kJ (68Kcal)/kg 0.75/day.11 Approximately half of the dogs in the recently published study demonstrating weight regain in pets10 regained significant amounts of weight after reaching their target. However, even in those dogs who regained weight, the majority (90%) regained less than half of the weight they had originally lost, thereby suggesting that postweight- loss rebound may be less common and less marked in dogs than in humans.9 Furthermore, the type of diet used during the maintenance phase following weight loss was found to be significantly associated with the likelihood of pet dogs showing regain.10 Switching to a standard maintenance diet post-weight loss significantly predisposed pets to regaining weight and this is thought to be due to the small dietary ration that is required for maintenance following weight-loss. The daily ration is likely to be too small to produce satiety, even though it fulfils the energy requirements of the pet. In the dogs that continued on a weight loss diet but at a ration of sufficient proportion to allow them to maintain their target weight, there was no significant change in their body weight. The study this information has been taken from involved a long-term follow-up of its patients (33 patients with a median duration of follow up of 640 days), so these findings may well result in significant changes to our future recommendations for dietary recommendations in post-weight-loss dogs. A further benefit that results from feeding a weight-loss diet longer term may include a reduced likelihood of nutrient deficiencies developing. This is because, whilst standard maintenance diets are designed to be complete and balanced when fed at National Research Council recommended maintenance levels for healthy adult dogs, they are not designed for feeding at the levels typically required by dogs post-weightloss. Weight-loss diets, on the other hand, are designed to be fed at lower energy levels and therefore have increased levels of protein, vitamins and minerals in relation to their energy content to compensate.

Summary

The findings from the recent studies discussed in this brief review reveal that a HPHF diet is not only beneficial during weight-loss for maintaining satiety, but may also be beneficial post-weight-loss to help maintain the pet at its target weight. HPHF diets have been  developed as a result of the on-going excellent research and are a good choice to start with when recommending a weight-loss programme for your client’s pets. The only reasons not to choose a HPHF diet are if larger feeding volumes are undesirable or the greater stool volume associated with higher fibre diets is not convenient. If this is the case, there are also high protein, moderate fibre weight loss diets available, which also have great success levels in patients on weight lost regimes. 

Acknowledgements

The author would like to thank Dr Alex German from the University of Liverpool and Dr Pauline Devlin of Royal Canin for their support, advice and valuable comments.
  1. Weber, M., Bissot, T., Servet, E., Sergheraert, R., Biourge, V. and German, A. J. (2007) A high-protein, high fibre diet designed for weight loss improves satiety in dogs. J Vet Intern Med 21 (6): 1,203-1,208.
  2. Bissot, T., Servet, E., Vidal, S. et al (2010) Novel dietary strategies can improve the outcome of weight loss programmes in obese client-owned cats. J Fel Med Surg 12 (2): 104-112.
  3. German, A. J., Holden, S. L., Bissot, T., Morris, P. J. and Biourge, V. (2010) A high protein high fibre diet improves weight loss in obese dogs. The Veterinary Journal 183 (3): 294-297.
  4. German, A. J. (2006) The growing problem of obesity in dogs and cats. J Nutr 136 (7 Suppl): 1,940S-1,946S. 
  5. Bergmann, J. F., Chassany, O., Petit, A. et al (1992) Correlation between echographic gastric emptying and appetite: influence of psyllium. Gut 33 (8): 1,042-1,043.
  6. Russell, J. and Bass, P. (1985) Canine gastric emptying of fibre meals: influence of meal viscosity and antroduodenal motility. Am J Physiol 249 (6 Pt 1): G662-667.
  7. Servet, E. et al (2008) Ability of diets to generate  satiety” in cats. (abstract). J Vet Int Med 22: 1,482.
  8. German, A. J., Holden, S., Bissot, T., Morris, P. J. and Biourge, V. (2008) Changes in body composition during weight loss in obese client-owned cats: loss of lean tissue mass correlates with overall percentage of weight lost. J Fel Med Surg 10 (5): 452-459.
  9. Mann, T., Tomiyama, A. J., Westling, E. et al (2007) Medicare’s search for effective obesity treatments: diets are not the answer. Am Psychol 62 (3): 220- 233.
  10. German, A. J., Holden, S. L., Morris, P. J. and Biourge, V. (in press) Longterm follow-up after weight management in obese dogs: the role of diet in preventing regain. The Veterinary Journal e-pub ahead of print, May 2011.
  11. German, A. J. et al (in press). Low maintenance energy requirements of dogs after weight loss. British Journal of Nutrition.
  12. Lund, E. M., Armstrong, P. J., Kirk, C. A. and Klausner, J. S. (2006) Prevalence and risk factors for obesity in adult dogs from private US veterinary practices. Intern J Appl Res Vet Med 4 (2): 177-86.
  13. Bach, J. F., Rozanski, E. A., Bedenice, D. et al (2007) Association of expiratory airway dysfunction with marked obesity in healthy adult dogs. Am J Vet Res 68 (6): 670-675.
  14. German, A. J., Hervera, M., Hunter, L. et al (2009) Improvement in insulin resistance and reduction in plasma inflammatory adipokines after weight loss in obese dogs. Domest Anim Endocrinol 37 (4): 214-226.
  15. Taken from the Pet Food Manufacturer’s Association website: www.pfma.org.uk/_assets/images... general/file/PFMA_WhitePaper% 20Final.pdf.
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