Although a pet’s body weight (BW) alone may not always provide a definitive diagnosis of obesity, companion animals are generally considered to be overweight when their mature weight exceeds ideal BW by five percent or more, while obesity is defined as the excessive accumulation of adipose tissue in body and occur when dogs are gaining more than 30 percent over their optimal body weight.
Health problems associated with obesity…
Overweight and obese conditions are associated with the development of various health problems like developing hypertension, steoarthritis, mammary tumours, elevated blood triglycerides and pancreatitis. Overweight dogs are also more likely to be insulin resistant, hyperinsulinemic and glucose intolerant. So we have to eliminate the root cause of all these diseases to secure our pets’ healthy life with longevity.
Causes of obesity…
Obesity in pets occurs due to various causes or predisposing factors like genetic factors, chronic imbalance of energy, endocrinological factors, diseased conditions etc.
- Genetic factors: Genetic factors are responsible for obesity e.g. Labrador retrievers have a higher incidence of obesity than is seen in other breeds, but the role of inheritance in canine obesity needs more detailed research studies.
- Chronic imbalance of energy: The fundamental cause of obesity is a chronic imbalance of energy, i.e. if they are consuming more energy than they are expanding. Over a long period of time, even a relatively small daily energy surplus will lead to gradual weight gain and obesity. This can occur when a dog has excessive dietary intake of calories (food and treats) or when there is a reduction in energy expenditure (reduced activity, illness or injury resulting in less exercise, etc).
- Drugs: There are some medical conditions like endocrinopathies, hyperadrenocorticism and hypothyroidism, and drugs such as steroids and anticonvulsants are responsible for obesity. But the primary reason that weight gain occurs in dogs on steroids or with hypothyroidism is that they have either increased food intake or decreased energy expenditure (or in some cases, both).
- Hormonal changes: Hormonal changes cause change in levels of leptin, progestins, and other hormones that result in increased appetite, and reduced energy metabolism and metabolic rate.
- Diseased condition: These include conditions like neutering, being middle-aged, inactivity or confined lifestyle. In addition, because feeding dogs is a social interaction, feeding and food interaction with the dog can become a problem resulting in overfeeding and inappropriate food intake patterns.
Diagnosis of obesity…
Accurate diagnosis of obesity is important for devising a treatment plan and achieving optimal weight loss for the animal companion. Comparing current BW to an estimate of ideal BW is a helpful starting point. Ideal BW can be estimated through a physical examination of the animal, obtaining information from the owner and from medical records of the pet’s weight shortly after attaining mature weight. The use of Body Condition Score (BCS) protocols provides an additional assessment of body fat and condition based on 5 or 9 points scale. BCS takes into account skeletal frame size and physical assessments of subcutaneous and abdominal fat deposits, and has been shown to provide a reliable method for diagnosis of obesity.
Comparisons of body composition data collected using dual energy X-ray absorptiometry (DEXA) with assessments using a BCS system have revealed significant and positive correlations between BCS and percent body fat in dogs. In addition to these diagnostic tools, subjective evaluation of the animal’s gait, exercise tolerance, and overall appearance can be used to support a diagnosis of obesity. The most precise and accurate tests that are used in research settings are costly, not easy to use and are invasive, and thus are not ideal for clinical practice. Examples of the most common research tools used for assessment of body composition include chemical analysis, densitometry, dual-energy X-ray absorptiometry (DXA), subcutaneous or visceral ultrasonography, CT or MRI.
Management of obesity in dogs…
The management of obesity includes a multifaceted approach as it is a long and tedious process with sincere involvement of not only our pets but their pet parents too. It is quiet difficult to overcome the feeding, behavioural, social, metabolic, and hormonal interactions but careful planning and its proper execution can give good results.
There are two important goals in establishing appropriate dietary therapy regimens, which include:
- Caloric restriction: It must occur without concurrent protein starvation to prevent loss of lean muscle tissue during weight loss. Once you have set the appropriate weight loss target for the pet, then you can calculate the energy restriction that will be required to achieve the goals you have set. Ideally, the best way to set the new energy intake is to reduce intake to 60 percent to 80 percent of the pet’s current intake. To provide safe, but efficient weight loss, the dog should not lose more than 1–2 percent of its body weight/week. A slower rate of loss can be discouraging to pet parents, but rapid weight losses can result in excessive losses of lean body mass (LBM). Generally, it is reasonable to attempt to achieve a loss of 20 to 25 percent of BW over an 18-week period (provided the animal was already over weight). A primary goal during obesity treatment is to minimize lean tissue losses while allowing for safe adipose tissue loss.
- Crude fibre: High amounts (10 to 20 percent) of crude fibre in the diet of animals. The purported benefit of these products is that the increased bulk, reduced caloric density, and decreased digestibility of a high-fibre diet will contribute to satiety and cause a decrease in voluntary energy intake.
In addition to reducing the energy intake of pets who are overweight, it is also possible to increase weight loss by increasing energy expenditure through increased exercise. In obese dogs, as in obese humans, it is important to start slow with an exercise program, and only very gradually and slowly increase the duration and intensity of the exercise. In some dogs, exercise may be impossible, due to severe joint problems or exercise intolerance or due to inability of the owners to exercise with their pet. In these dogs, very minimal activity, or low impact activity, such as a treadmill or water treadmill may be needed to allow safe, non-painful activity.
Consultation with a veterinary physical rehabilitation specialist is often very helpful in determining appropriate activities for the dog. This can also be part of the overall diet and weight reduction plan, and evaluation of the pet’s progress can occur in conjunction with the visits to the rehabilitation programme.
Elevated blood levels of the hormone leptin are another physiological alteration that occurs with overweight conditions. Dietary manipulation of leptin levels may be important for the control and management of obesity.
The different pharmacological approach to weight management include some drugs that reduce fat uptake from the intestine by inhibiting gastrointestinal lipases e.g. orlistat and sibutramine. Some drugs reduce appetite and increase metabolism (fat burning).
Nutraceutical therapy is also an increasingly important aspect of therapy of weight loss. L-Carnitine, an amino acid synthesized from methionine and lysine in the liver, has been used for several years to enhance fat metabolism and help maintain lean muscle mass during weight loss. Incorporation of 100–300 ppm of L-Carnitine into diets has been shown to reduce lean muscle mass loss during weight loss lab animals, primarily due to enhanced fatty acid oxidation and energy availability for protein synthesis. Other nutraceutical alternatives that may enhance weight loss, but require additional evaluation include conjugated linoleic acid (CLA) and dietary diacylglycerol (DAG).
Social behaviour management
Many dogs become obese due to social bonding that occurs with pet parents and their dogs during feeding. This human-animal bond activity results in a strong behavioural component to the development of obesity that must be addressed. In order to achieve success in changing these behaviours, it is important to substitute low calorie treats, games, or grooming activities for table scraps or other high calorie treats. Begging for food is more of a behavioural problem than a hunger problem, and if this relationship is not considered in weight loss programmes, the plan is doomed to fail. In some cases, consultation with a veterinary behaviourist is an important part of the overall plan for weight loss.
On a concluding note…
Management of obesity is a multifaceted task. But, not to forget it’s the enthusiasm and strict sincere efforts of pet parents that will lead to successful management of obesity.
(Dr Shrikant Soma Patil and Dr Amit Sharma are asst professors at College of Veterinary Sciences & AH, Agartala; Dr K B Kore is asst professor at College of Veterinary Sciences & A.H., Navsari Agriculture University, Gujarat; and Dr Pallavi Mirajkar is MVSc in livestock economics.)