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Obesity, Osteoarthritis and Nutrition

Obesity and Modern Lifestyle

Obesity is on the rise in developed countries, affecting adults, children and pets. The World Health Organisation has deemed obesity as a global epidemic and it is now being increasingly focussed on in the media. Statistics vary, but near half the human population in developed countries such as Australia, the USA and Great Britain is overweight or obese. It is generally thought that the trend towards weight gain is environmental, a result of decreased physical activity and a preliminary indoor lifestyle without appropriate adjustment to dietary intake. Everywhere we look there are aids to help us save time and energy. Our cities and town are so big that we have to drive to get to our destinations instead of walking of cycling, and then we are further aided by elevators and escalators so that we don’t have to walk up the stairs. At home, the children are watching TV and playing computer games instead of playing in the yard or neighbourhood, and the dog is housebound, not getting the exercise he needs. Our lifestyle has changed drastically in the last couple of decades with emerging technologies, and they are literally causing our demise.

Definition and Cause

Weight gain, when nutritional, is a response to a positive energy balance, where the energy input (food intake) exceeds that of the energy output or maintenance energy requirement (MER). MER is resting energy requirement (RER) or basal metabolism plus energy expenditure due to work done; i.e. exercise, housework, walking to work etc. Surplus intake, energy exceeding MER, is stored by the body as fat or adipose tissue. This is an evolutionary safeguard to help us through leaner times and reduced food intake, such as winter when pickings are few and we experience a negative energy balance. However, humans and domestic dogs in developed countries rarely encounter a natural lean period, and the weight gain becomes chronic.

Prevalence

The modern lifestyle is also affecting our dogs, as the canine population is now displaying the same weight gain tendencies as their human companions. Studies in several countries and by several authors reveal that a great proportion of dogs are overweight and/or obese. The numbers vary between studies, so it is hard to estimate a true figure, but they all convey the same picture. Colliard et al. (2006) reports of 38.8% overweight dogs in France and McGreevy et al. (2005) reports 41% in Australia.

Risk Factors

Risk factors of obesity have been studied, and the most prevalent are inactivity, neutering, female gender, rural or semirural dogs, breed (esp. Retrievers and Hounds) (McGreevy et al.) and owner profile (Kienzle et al., 1998). Neutering is thought to contribute to weight gain due to altered basal metabolism and also altered behaviour in dogs. Neutering reduces a dog’s proneness to wandering and display of territorial behaviours, affecting both basal energy requirement and energy expenditure. Kienzle et al. found that owners of obese dogs were often obese themselves. Obese owners mostly belonged to a lower socioeconomic group, fed the dogs a lower cost prepared food, and displayed several behaviours associated with interaction, bonding and feeding of their dogs. They also found that owners of obese dogs had less interest in canine nutrition than did the owners of normal dogs. Several studies have also looked at owners perceptions of their dogs’ body condition and found that owners of overweight or obese dogs generally underestimate their dogs’ body condition with about one point on a 9 point scale, therefore rarely recognising that their dog is indeed overweight or obese (Robertson, 2003, Laflamme, 2005, and Colliard et al.).

Complications of Obesity

Several studies have been done on the side effects of obesity. There is considerable evidence that above ideal weight in dogs contribute to the onset of diabetes, orthopaedic disease and injuries, endocrine and metabolic disease, cardiorespiratory problems, neoplasia and several others (German, 2006). Not only does obesity make clinical evaluation and examination of patients more difficult, it also increases risks associated with anaesthesia, which one is more likely to require if the dog is obese as it is more likely to suffer from a condition that may require surgery. Probably the largest study done on the effects of obesity on orthopaedic disorders and longevity was carried out by Nestle Purina, and Kealy et al. have written several papers on results obtained from the longitudinal, life-long trial. Diet restriction; maintaining dogs at an optimal body condition score, has been found to lower the incidence of hip dysplasia in growing dogs (Kealy et al., 1992), reduce prevalence and severity of OA in adult dogs (Kealy et al, 2000), increase the lifespan and delay the onset and degree of age-related changes and chronic conditions (Kealy et al., 2002).

Osteoarthritis

Osteoarthritis is a common complaint, especially in overweight dogs, and negatively affects the individual dog’s quality of life, as pain limits movement. In the previously mentioned Nestle Purina study, 77% of the control-fed (overweight) dogs developed OA in either 2 or 3 joints at 8 years of age (Kealy et al., 2000). Theories about the onset of OA vary somewhat in literature, and there might be more than one factor causing it. OA has been reported following trauma, either through direct joint injury or resultant alteration in biomechanics, and excessive loading of joints (obesity). Adipose tissue also releases inflammatory cytokines, and elevated levels of inflammatory mediators are found within obese subjects, and therefore obesity is thought to contribute to the onset of OA on a pathological level also, not just biomechanical. Obesity increases the oxidative stress on the body which is also associated with the onset of OA (Laflamme). So, in summary; obesity is probably the most important risk factor for OA, as it incorporates inflammatory, biomechanical and oxidative risk factors.

Prevention

Environmental obesity is obviously best avoided all together. Prevention of obesity is possible in humans through education promoting healthy eating habits and physical activity (Flodmark et al., 2006). Dog owners should therefore be made aware of the needs of their dog, such as the need for exercise, the need to maintain optimal body condition and nutritional needs. Most dogs attend a veterinary clinic regularly, especially as puppies for vaccinations. Familiarising an owner with a body conditioning chart (verbal and visual) and provision of verbal and written information from the veterinarian may prove useful. There has been suggestion in some literature that veterinarians may not affirm good body condition when encountered, suggesting that owners should be diligently praised for the condition of their dog if within an ideal range. This might motivate people to keep their dog in a good body condition, and it may be complemented on by the veterinarian at the next visit also. Treatment of the obese and arthritic patient is one that most animal physiotherapist will encounter. Quite likely, the patient will also present with lameness also, and OA may already be present in more than one joint.

The Importance of Protein

Weight loss through diet and exercise is the most common and effective means of losing weight, however, it may be easier said than done as many factors must be considered, and it is not as simple as just feeding the dog a smaller serving of their normal food as this may lead onto other problems. Dogs require a relatively high proportion of protein in their diet, approximately 20% (Fleeman, 2006). Older dogs require higher levels of protein (+50%) to maintain nitrogen balance and to maximise their protein reserves (Laflamme, review). This is especially important to note, as this is also the patient group which is most prone to developing OA. On the other hand, they also have lower calorific needs. Weight loss can only be achieved through negatively balanced energy expenditure, i.e. calorie intake is less than total amount of energy requirement and expenditure. If the normal food is given in smaller amounts, proportion of protein may well fall below minimum requirement, and thus cause loss of lean body mass. Lean body mass, or fat free mass (FFM) as it is often referred to, is the proportion of the body that consist of core structures and organs such as the skeleton, muscles, skin, coat, nervous system, circulatory and respiratory system, and internal organs. It is never a goal to loose any of the lean body mass, but this can happen and quite quickly if protein containing essential amino acids is insufficiently supplied. The body can manufacture its own non-essential amino acids, but not essential ones which have to be provided in the diet. Lean body mass determines an animals RER. Consequently, if the lean body mass decreases, so will the dogs RER. Another important note is that MER is highly variable, and dependant on several factors such as; breed (hereditary proneness, gender (F>M), neutering status, activity level (work, size of yard, companion, amount of exercise) and age.

Protein is very important to the diet. The dogs body is made up from 50% protein (dry weight), and amino acids are crucial in maintenance, health and growth of the bodies tissues. Protein, broken down to amino acids, is used to produce enzymes, hormones and blood proteins, which are crucial to bodily functions such as digestion and absorption of nutrients, metabolism, regulation of glucose, and the immune system. Amino acids are also crucial in the synthesis of tissue protein, especially in relation to growth and healing, and are also a primary fuel for producing energy. The body also continuously breaks down and manufactures new body proteins, a process known as protein turnover, which obviously can only be done if there are available amino acids. Dietary protein deficiency reduces the protein turnover, and may thus affect any or all of the functions of the body that is dependant on amino acids, dictating the overall health of the animal.

From a physiotherapist’s perspective, primarily concerned with the musculoskeletal system, sufficient levels of highly digestible protein in the patient’s diet is of upmost importance. Physiotherapists ask the body to produce more work and gain strength, and often; tissues are also healing. Neither is possible unless protein intake is adequate. A dog’s body will simply not be able to provide the needed amino acids to build muscle bulk, if sufficient levels to do so are not present. Adipose tissue can provide fuel for energy, and therefore can be lowered in the diet, to promote utilisation of this. Similarly, intake of carbohydrates can be reduced, to encourage burning of body fat. To make up lost bulk of food, indigestible fibre is added to the diet so that the dog gains a sense of satiety, and is not left wanting for more. When reducing the calorie intake through adjusting a dog’s diet, the minimum requirement of RER is sought. Several authors report diet restriction as a percentage of MER, however, one must take care to maintain optimal nutrition, and aiming towards at least covering the animals RER seems the most appropriate. It may be wise to increase to proportion of protein to above 20%, as a physiotherapist will seek to also increase the lean body mass through work, and also take into account that healing needs to be optimised. Increasing the lean body mass will increase the basal metabolism, and therefore aid weight loss, in addition to priming the body’s capacities for the load it is carrying.

Hannah and Laflamme (1998) studied weight loss and loss of lean body mass with three dietary protein levels (20%, 30% and 39% of calories). They found that the group given 20% lost approximately twice the amount of lean body mass as the other two groups did, indicating that 20% is too low a level when on a calorie restricted diet, as much of the weight lost is of the lean body mass. Diez et al. (2002) found similar on their test groups, which were given 23.8% and 47.5%. Weight loss was greater in the lower protein group, but loss of lean body mass was also greater. Wakshlag et al. (2003) studied effects of protein ratios on normal dogs, and found that the group fed a 12% protein diet over 10 weeks had a significant loss of lean body mass and increased levels of fat mass. There were no alterations in the group fed 28% protein, despite same amount of calories fed. There were also no differences in weight, or body scoring for either group, before or after the study. This illustrates that it may not be evident from examination alone that a dog is protein deficient, as it may present a healthy. Yoo et al. (2006) found no difference between RER or change in body composition in groups of dogs fed a weight maintenance diet either high or low in fat. Both diets contained > 20 % protein, which may explain why there was no change seen. Blanchard et al. (2004) confirms that a low calorie food, with a high protein: energy ratio facilitates rapid weight loss whilst preserving lean body mass. They fed obese Beagles at 50% of MER, on a commercial, nutritionally balanced weight-loss food containing 26% protein.

It is clear that in order to loose weight effectively and safely, nutritional needs have to be met. Many people like to prepare the food for their dog themselves, but there are several disadvantages with this, as the food may not be nutritionally complete or balanced and it may end up like an advanced science project if it is to be done well. It might be time, cost and labour saving to simply purchase a quality purpose-specific commercial food from a reputable seller, such as a veterinary clinic. Many veterinary practices have weight loss clubs/classes these days and this is probably a good environment for owners of obese or overweight dogs to attend for education and feedback.

Treating the Overweight and Arthritic Canine Patient

An overweight dog suffering from osteoarthritis will have painful joints, exacerbated by the excessive weight he is carrying, and higher weight bearing activities such as jumping and running. He is likely to be lethargic and in a state of poor physical fitness, and have reduced ROM, as end range demands more muscle work and has a tendency to be sore.

1: Diet

Weigh the patient and calculate RER from reference of ideal body weight. Prescribe a weight loss diet based on RER x 1, and explain importance of this to the client. It would be beneficial to provide written information that the client can take home and read at his or her own leisure, as it is very hard to remember specific information given only verbally. A food specific to arthritis which meets protein demands should be opted for as these may contain specific lipids (polyunsaturated), glucosamine, chondroitin sulphate and antioxidants which have been reported as beneficial to deteriorating joints (Laflamme, review). As older dogs appear to have higher protein requirements and are also the age group in which OA is most prevalent, it might be advisable to consider a food with at least 30% protein: energy ratio. Information about extra treats should be provided, as these must be accounted for on the daily calorie intake. Humans are very closely bonded with their dogs, and often feel that food is part of that relationship. If this is an important aspect of the particular client-dog relationship, it should be explained that it can still be done, but perhaps opt for a lower calorie treat or set aside some of the food portion for this purpose. Also, suggest that the client reward their dog in other ways, like a small walk, cuddling, play a game or any activity that their dog enjoys.

2: Maintaining ROM

Painful joints under a heavy body will dictate that the animal will attempt to compensate by walking on straight legs and use short strides, therefore not venturing into ends of range. Loss of degree of ROM can be very hard to regain due to adaptations of the synovial membrane and structures surrounding the joint, such as muscles shortening. A stretching program for the extremities and vertebral column should be implemented. This is an activity which the owner can also perform at home. OA tends to affect larger, weight bearing joints such as the elbow, shoulder, hip and stifle. It is very important to keep in mind that if one asks too much of a client, none will be done. If one asks less, it is more likely to be achieved.

3: Exercise

As the patient is likely to be in poor physical condition and also have pain or discomfort on movement, care must be taken when developing an exercise program. Swimming is excellent as the exercise is non-weight bearing and more comfortable for the dog. The prevalence of adipose will also help in floatation, and may make the dogs feel more secure in the water. The use of an underwater treadmill is also a good alternative, as this is semi-weight bearing and probably a more aerobic form of exercise. Pools and underwater treadmills may not be available though, and even if they are; probably will not be used every day. Gradually increasing walks over relatively flat terrain is a realistic option, as this will stress the cardiovascular and musculoskeletal system, and is also measurable by the client. The dog should be given a break when he shows signs of fatigue, and the exercise should not be excessive. As the dog looses weight, exercise tolerance should increase and the dog should exhibit signs of reduced pain (happier demeanour, decreased lameness, increased speed of gait).

4. Quality of life

If a dog is home alone all day, and is additionally not feeling optimal, he is likely to spend a large amount of time asleep. His life might be spiced up by a canine companion, even if it is just the dog next door visiting, or the acquisition of a suitable companion. Supply of toys such as the Kong™, a hollow dense rubber toy which can have treats or peanut butter placed inside it, can occupy a dog for hours. Although it is a fairly low intensity activity, it does have a higher energy output than sleep or lying still, and it might be good for the morale and mental status of the dog. Supplying objects or toys that interests the dog around the yard or house, will elicit the dog to explore and move around more. Another treat is to take the dog (providing it likes other dogs) to a local dog park and let him wander around for a while, sniffing out the place.

References

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Colliard L, Ancel J, Benet JJ, Paragon BM, Blanchard G (2006) Risk factors for obesity in dogs in France. Journal of Nutrition. 136(7 Suppl) pp 1951-1954

Diez M, Nguyen P, Jeusette I, Devois C, Istasse L, Biourge V (2002) Weight loss in obese dogs: evaluation of a high-protein, low-carbohydrate diet. Journal of Nutrition. 132(6 Suppl 2), pp 1685-1686

Fleeman L (2006) Canine and equine nutrition. In “ANIM 7112 Husbandry of Companion and Competition Animals.” (University of Queensland, Australia)

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Hannah SS and Laflamme DP (1998) Increased dietary protein spares lean body mass during weight loss in dogs. Journal of Veterinary Internal Medicine. 12, pp 224

Kealy RD, Lawler DF, Ballam JM, Lust G, Biery DN, Smith GK, Mantz SL (2000) Evaluation of the effect of limited food consumption on radiographic evidence of osteoarthritis in dogs. Journal of the American Veterinary Medical Association. 217(11) pp 1678-1680.

Kealy RD, Lawler DF, Ballam JM, Mantz SL, Biery DN, Greeley EH, Lust G, Segre M, Smith GK, Stowe HD (2002) Effects of diet restriction on life span and age-related changes in dogs. Journal of the American Veterinary Medical Association. 220(9) pp 1315-1320

Kealy RD, Olsson SE, Monti KL, Lawler DF, Biery DN, Helms RW, Lust G, Smith GK (1992) Effects of limited food consumption on the incidence of hip dysplasia in growing dogs. Journal of the American Veterinary Medical Association. 201(6) pp 857-863

Kienzle E, Bergler R, Mandernach A (1998) A comparison of the feeding behaviour and the human-animal relationship in owners of normal and obese dogs. Journal of Nutrition. 128(12 Suppl) pp 2779-2782

Laflamme DP (2005) Nutrition for aging cats and dogs and the importance of body condition. Veterinary Clinics of North America - Small Animal Practice. 35(3) pp 713-742

McGreevy PD, Thomson PC, Pride C, Fawcett A, Grassi T, Jones B (2005) Prevalence of obesity in dogs examined by Australian veterinary practices and the risk factors involved. Veterinary Record. 156(22) pp 695-702

Robertson ID (2003) The association of exercise, diet and other factors with owner-perceived obesity in privately owned dogs from metropolitan Perth, WA. Preventative Veterinary Medicine. 58(1-2) pp 75-83

Wakshlag JJ, Barr SC, Ordway GA, Kallfelz FA, Flaherty CE, Christensen BW, Shepard LA, Nydam DV, Davenport GM (2003) Effect of dietary protein on lean body wasting in dogs: correlation between loss of lean mass and markers of proteasome-dependent proteolysis.
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Yoo S, Ramsey JJ, Havel PJ, Jones PG, Fascetti AJ (2006) Resting energy expenditure and body composition of Labrador Retrievers fed high fat and low fat diets. Journal of Animal Physiology and Animal Nutrition. 90(5-6), pp 185-191