Obesity is an endemic disease of domestic cats, especially in affluent western societies. The number of obese or overweight cats ranges from 15% to 35%, with practitioners estimating even higher numbers in some areas.
A body weight of greater than 20% over the ideal weight of the animal is generally accepted as obese for cats, which means that a 4 kg cat that gains 1 kg is considered obese. Obesity in cats not only is a cosmetic problem but also increases the risk of development of diabetes and hepatic lipidosis and is associated with increased incidences of many other conditions, such as lower urinary tract disease and osteoarthritis. Presuming that obesity in cats is similar to that in dogs and humans, this condition will also shorten the life span of affected cats.
Although many aspects of obesity are similar among species, numerous differences also exist. For example, obesity in people frequently is associated with dyslipidemia. Development of cardiovascular disease and hypertension has been attributed primarily to an increase in low density lipoprotein (LDL), the so-called 'bad' cholesterol, and a decrease in high density lipoprotein (HDL), the so-called 'good' cholesterol. In comparison, cats have elevated HDL concentrations when they become obese, probably because of lack of cholesterol-ester-transfer protein (CETP), an enzyme involved in the transfer of cholesterol and lipids between different lipoproteins. Interestingly, this enzyme recently has been targeted to treat dyslipidemia in people; that is, inhibition of CETP leads to increased HDL and decreased LDL concentrations.
Diseases associated with obesity
- Metabolic abnormalities
- Insulin secretion in obesity
- Insulin resistance in obesity
- Glucose intolerance
- Hepatic lipidosis
- Feline asthma
- Urogenital system
- Feline lower urinary tract disease (FLUTD)
- Functional alterations
- Joint disorders
- Respiratory compromise e.g., dyspnea
- Exercise intolerance
- Heat intolerance/heat stroke
- Decreased immune functions
- Increased anesthetic risk
- Decreased lifespan
Although changes in both insulin secretion and insulin resistance play a primary role in the pathogenesis of obesity and diabetes mellitus at the cellular level, the rising incidence of diabetes mellitus in cats must be related to domestication. Changes in diet (featuring higher carbohydrate content in commercial food) and restriction to outdoors resulting in reduced exercise have been major triggers for rising incidences of feline obesity which parallel rising human obesity levels. Coupled with this is the proclivity of clinicians to address the symptoms of this disease (high blood sugar) rather than the underlying psychological obstacles to health (boredom eating by cats and lack of exercise).
The incidence of diabetes in cats clearly has increased in the last two decades, likely because of the increase in risk factors in general and obesity in particular. However, not all obese cats progress to become diabetic. Conversely, not all diabetic cats are obese at the time of diagnosis or ever have been. Not all diabetic cats have an increased amount of pancreatic amyloid deposition, and even cats with increased islet amyloid concentrations may have only transient diabetes. Last, not all diabetic cats respond to the same treatment. Many factors are therefore likely involved in the pathogenesis and clinical presentation of this disease.
Management of obesity is complex; it involves addressing the causes of clinical obesity while treating the dietary and medical disorders inherent in the condition . It can be frustrating, time consuming and often unrewarding. The evidence that obese cats have nearly three times the risk of death than cats of ideal weight helps to convince care-givers to continue treatment despite short-term failures.
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