The number of animals that are overweight or obese has reached epidemic proportions in the US and other countries. It is the
leading nutritional disease in pets of western societies. Identifying obesity and determining its cause is not a diagnostic
challenge. Weight gain occurs when an animal is in positive energy balance for a prolonged period of time. Energy intake increases,
energy expenditure decreases, or both happen concurrently. Although it is very common, and not difficult to understand, obesity
is very difficult to treat.
Prevalence of Obesity in Dogs and Cats
The number of pets that are overweight or obese has reached epidemic proportions in the USA and other industrialized countries.
There are various reports as to how common obesity is, but it has been shown that just over 35% of adult cats in the USA were
overweight or obese. In addition, 45% of the cats aged 10-11 were considered overweight or obese. Studies investigating the
prevalence of overweight/obesity in dogs have varied from 24% to 34%.
Obesity prevention in pets needs increased emphasis with focus on wellness plans through owner education. Significant health
benefits to maintaining a normal to lean body weight have been shown in dogs and other species. The veterinary visit for spaying/neutering
is an important, but often neglected, opportunity to reassess diet type and feeding management and make appropriate awareness
of obesity issues to clients.
Risk Factors for Obesity in Dogs and Cats
a. Dogs - Specific breeds are more likely to become overweight. These include but are not limited to Shetland Sheepdogs, Golden
Retrievers, Dachshunds, Cocker Spaniels, Labrador Retrievers, Dalmatians, Rottweilers, and Mixed Breeds.
b. Cats -Mixed breed (DSH, DLH, DMH) and Manx cats were found more likely to be obese than most purebred cats.
2. Gender/neuter status-
a. Dogs - Neutered female dogs are about twice as likely to be overweight than are intact female dogs. Similar trends have
been seen in castrated male dogs.
b. Cats - Male cats are predisposed to being overweight. Neutering further increases the risk of obesity by decreasing the
metabolic rate by at least 25%. Removal of estrogens may also increase food consumption independent of the decreased metabolic
rate. This may also be accompanied by an increased appetite following surgery.
3. Age- Risk increases with increasing age in both dogs and cats
4. Activity- Reduced activity increases risk for weight gain in both dogs and cats.
5. Food and feeding- Highly palatable foods, free choice feeding and excessive treats. In particular, feeding high fat foods
is associated with obesity.
6. Other associations – In cats, other factors such as apartment dwelling, presumably due to decreased exercise opportunities
- this is "softer" data, but seems to be a commonly observed association.
Health Risks of Obesity
Studies investigating overweight dogs and cats have identified many of the same health problems observed in humans. In cats,
T2DM, neoplasia, dental disease, dermatologic diseases, and lower urinary tract problems have been associated with obesity.
In dogs, overweight or obesity has been linked with diabetes, pancreatitis, cruciate ligament rupture, hypothyroidism, hyperadrenocorticism,
lower urinary tract disease, oral disease, neoplasia dyslipidemia, osteoarthritis, hypertension, altered kidney function.
In addition, although harder to measure, obesity exacerbates existing musculoskeletal problems, respiratory distress from
upper airway obstruction, and pregnancy complications, and is associated with delayed wound healing, increased anesthetic/surgical
risk, and probably reduced life expectancy. Obesity also makes tasks like collecting blood samples and placing intravenous
catheters much more difficult.
Preventing or treating obesity may delay and or prevent many of these obesity-related diseases. A successful weight loss program
requires a reduction in caloric intake (owner compliance) and an increase in physical activity. Weight loss studies in dogs
have found positive associations on biomarkers associated with obesity-related diseases. Weight loss in dogs has been associated
with a reduction in triglycerides, cholesterol, thyroxine and leptin. In addition, weight loss in dogs lead to an increase
in insulin sensitivity and lowering of adipokines linked with insulin resistance (tumor necrosis factor alpha and insulin
like growth factor-1).