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A healthy weight starts with healthy habits

Innovative approaches emerging...

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01 April 2009, at 12:00am

Susan McKay reviews a problem of increasing magnitude

Pet obesity is a complex issue but one that we have become so accustomed to dealing with that there is a temptation to think we have heard it all before. But today there are more interested parties than ever who are keen to take on the hot potato of managing our couch potatoes. As a result, a range of innovative approaches is emerging.

 Taking a darker view, while some prefer to incentivise pet owners with “carrots”, there are increasingly powerful sticks to threaten those who fail to act. In January of this year two Labradors weighing 63kg and 52kg respectively were seized by the RSPCA upon authorisation from the police who suspected an offence under the Animal Welfare Act 2006. All of this despite claims from their owner that she had previously managed to reduce the dogs’ weights – in one case by as much as 23kg1.

 The Kennel Club has also got in on the act. Under its “Fit for Function: Fit for Life” campaign, the organisation has reviewed its breed standards.

 “One of the examples of a suggested amendment to a breed standard was the Labrador Retriever which included the preclusion of excessive weight,” explains Caroline Kisko, the Kennel Club’s spokesperson. While recognising that not every Labrador is overweight, the Kennel Club says it wants to “…encourage breeders and owners to think about their pet’s weight before it becomes a problem.”

Those vets who have seen Labradors in the show ring that they would consider distinctly porky will be relieved to think that judges will no longer be encouraged to believe that big is necessarily beautiful.

 Of course, some breeds face larger problems than others. There is some evidence to show that while some breeds regulate their energy intake to their requirement, that ability seems to have been lost in other breeds. Some breeds, such as the Newfoundland, have a lower energy requirement for their size, while the Great Dane has a relatively higher requirement and many factors can overwhelm the controls that do exist2.

 Very palatable food has been blamed by some as a causative factor and it has also been demonstrated that offering different foods causes many dogs to increase their intake. In other words, there’s always room for a yummy dessert even after you have eaten your fill of the main course.

 Fettman et al reported that body weight and food intake increased in cats three months after neutering3. In male cats this has been largely attributed to increased voluntary food intake, while in female cats there is a distinct slowing of the metabolic rate4,5. In dogs there is some evidence to suggest that fasting energy expenditure is reduced post neutering2.

Treatment options

 After the not insignificant challenges of persuading owners that their pet’s weight is a problem and getting their buy-in and commitment to a weight management programme, setting the target weight is the next obstacle.

 In many cases the target weight is established by rule of thumb methods, using breed standards. A more accurate measure may be to call our patients back in for a weight check when they have attained their adult body weight to establish a baseline against which future weight checks can be evaluated.

 In an ideal world a food log would be reviewed to help the clinician establish a suitable dietary programme and it would give some idea as to how many calories are required to support the current bodyweight.

 As a rough guide, in dogs reducing the calories to 50-60% of that required to support the ideal weight should result in weight loss and in cats reducing the calories to 50-80% of maintenance at the ideal weight. In reality, on-pack instructions for weight loss foods are likely to follow this model.

 Safe weight loss is accepted to be in the region of 0.5 to 2% per week and the calorie intake can be re-evaluated at intervals dependent on whether this target is met.

Diet

 Weight reduction diets have been extensively described and current thinking appears to suggest that using a higher protein diet is one of the more successful strategies. Hill’s Pet Nutrition points out that optimised protein levels increase satiety through stimulation of cholecystokinin secretion and independent of the protein intake, high levels of lysine and L-carnitine help maintain lean muscle mass.

 The role of fibre in satiety continues to be hotly debated and while the role of fibre in diluting the energy content of the food is easy to understand, the effects of various fibre types may eventually show that this is a much more complex story than it initially appears. Recent evidence suggests that a balanced fibre source, containing higher levels of soluble fibre rather than the traditional higher levels of insoluble fibre, can also stimulate satiety through glucagon-like peptide-1 secretion from the large intestine.

 Nutrigenomic studies, looking at multiple metabolic markers in blood, suggest that newer weight loss diets not only stimulate weight loss through calorie and satiety control, but have the potential to make animals become metabolically leaner as well as physically leaner6.

 This opens up the possibility of better, quicker weight loss programmes followed by more successful long-term weight control and reduced risk of rebound weight gain.

Exercise 

Although increasing exercise has long been advocated as part of a weight management programme, the calorie burning effects are relatively meagre. Embracing an exercise programme has other benefits however, such as increased access to the outdoors and increasing the pet’s muscle strength and flexibility.

 Many dogs that are overweight also suffer concurrent illness but can benefit from a tailored exercise programme that matches their individual needs.

 Rehabilitation specialist Lowri Davies of The Smart Clinic describes how she would approach such a case. “There are many considerations when designing an exercise regime for the obese animal, the primary one being not to exacerbate any on-going problem. An obese dog is enough of a challenge but an obese dog on three legs with a ruptured cruciate is a major problem.

 “Therefore, exercise with caution, put the groundwork in to strengthen the postural muscles first and improve proprioception and balance before any extensive walking regime. Aim to exercise at low heart rates, preferably monitoring the pulse and build up to at least 40 minutes daily.” 

Medication 

The use of medication to treat obesity has proved to be controversial and no doubt the ensuing debate about the rights and wrongs has helped to raise awareness of the pet obesity “epidemic”.

 Both Slentrol (dirlotapide) and Yarvitan (mitratapide), the treatments available in the veterinary channel, are selective microsomal triglyceride transfer protein (MTP) inhibitors. Both act at the level of the enterocyte to stop lipid absorption and have a locally generated effect on satiety.

 Annelies Hall of Pfizer Animal Health explains, “Slentrol partially decreases absorption of fat from the intestine into the systemic circulation. Digested fat is absorbed by enterocytes and packaged into chylomicrons with the help of MTP. In the presence of Slentrol, some of the dietary fat remains trapped in the intestinal cell and is sloughed with the intestinal cell every few days.

 “This ‘fat trapping’ triggers a satiety signal (via increased Peptide YY and other satiety hormones secreted by endocrine cells of the intestine into the bloodstream and acting on the hypothalamus in the brain) and subsequently reduces food intake.” 

Janssen Animal Health, the maker of Yarvitan, recommends that the certain situations: to help dogs suffering from co-morbidities (such as osteoarthritis) to reduce their clinical signs, as a short-term adjunctive therapy to “kick-start” a weight loss programme, to help re-motivate pet owners where traditional programmes have not succeeded alone and for dogs who are in need of surgery but are at a high anaesthetic risk as a result of their excess weight.

 The duration of treatment for Yarvitan is for two 21-day periods with a 14-day rest period between treatments. Slentrol can also be given for short periods, but it is also licensed for administration for up to 12 months duration, which suggests that this might be a particularly good option for those pets suffering profound weight gain where a shorter period of treatment may not give the desired results.

 Rebound weight gain is very likely to occur if a good dietary regime is not well established by the time the course of treatment comes to an end. Perhaps one consideration might be that this can be instituted near the end of the treatment course when owners have already been able to see the benefits of the pet being leaner and thus are better equipped to commit to a long-term weight maintenance programme.

 Compliance remains the key issue for most clinicians. Programmes such as the Hills VNA programme provide e-mail alerts for the client to attend weigh-ins and an on-line weight tracker. Pfizer Animal Health has also developed an action-centred approach to the management of obesity which categorises clients as “hikers” (those who have lapsed or failed), “sunbathers” (those who realise the problem but have taken no action) and “new arrivals” who are unaware that there is a problem. On this basis a range of communication techniques is suggested which will help to give food for thought.

 There are also some excellent resources, including weight management algorithms, available from the Weight Advisory Group (WAG) at www.canineobesity.info. Obesity in pets is increasingly appreciated to be a pathological state and as our understanding of the condition grows, so our approach should become accordingly more sophisticated.

 With an increasing array of new solutions available, it may pay to revisit practice protocols to see if more can be done to help these patients and their owners, particularly given their recidivist tendencies. An obese cat. Before and after photos of Barley, a regional winner in a Hill’s Pet Slimmer of the Year contest.

1. http://www.telegraph.co.uk/news/uknews /4331467/Fat-dogs-seized-by-RSPCA.html.

2. Small Animal Clinical Nutrition, 4th edition, 2000. Eds: Hand, M. S., Thatcher, C. D., Remillard, R. L. and Roudebush, P. Topeka, Mark Morris Institute.

3. Fettman, M. J., Stanton, C. A., Banks, L. L., Hamar, D. W., Johnson, D. E., Hegstad, R. L. amd Johnston, S. (1997) Effects of neutering on bodyweight, metabolic rate and glucose tolerance of domestic cats. Res. Vet. Sci. 62: 131-136.[Medline] 

4. Kanchuk, M. L., Backus, R. C., Calvert, C. C. et al. (1998) Neutering induces changes in food intake, body weight, plasma insulin and leptin concentrations in normal and lipoprotein lipase-deficient male cats. J. Nutr. 132: 1730S-1732S.

5. Hoenig, M. and Ferguson, D. C. (2002) Effects of neutering on hormonal concentrations and energy requirements in male and female cats. Am J Vet Res 63 (5): 634-639.

6. Yamka, R. M., Franz, N. Z. and Friesen, K. G. (2007) Effects of 3 canine weight loss foods on body composition and obesity markers. Intern. J Appl. Res.Vet. Med. 5: 3.

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