Why Are Some Dogs Obese?

A fat dog is not necessarily a happy dog. In fact, his health may be at serious risk, and he may even grow depressed. There are many reasons why pets become obese but the two main reasons are: Eating too much and not getting exercise enough. As long as a medium-sized dog is no more than a few pounds over its optimal body weight, there may be no cause for concern. But if the extra weight amounts to more than 15 percent over ideal body weight, the dog is clinically obese and there will be health risks to consider.

The greater an animal's caloric intake over the course of his life, the shorter that life span will be. People talk about vitamins and minerals, amino acids, and supplements that might keep our pets healthy, but caloric intake alone is the single biggest determinant of an animal's (or person's) life span. It's a simple formula: More calories = fewer years.

Obesity is accompanied by a set of physical problems that may contribute to an affected pet's premature demise. Fat dogs have an increased risk of developing cardiovascular disease, respiratory disease, liver disease, diabetes, orthopedic problems, and even neurological problems. As our dogs' protectors, we should take obesity seriously and feed and exercise our canine companions sensibly.

Reduce Caloric Intake

One way to reduce the caloric intake is to reduce the amount of food we are feeding – but this should be done with proper forethought and appropriate advice. "Crash diets" are never appropriate. Drastic reduction of food intake:

a) Is potentially dangerous
b) Is inhumane
c) Contributes to the "yo-yo syndrome" of sudden weight loss followed by rapid weight gain if the original feeding regimen is reinstated.

The yo-yo syndrome is the reason so many people fail to lose weight when they put themselves on a diet. If any animal (including humans) does not get enough food for a while, its body goes into "crash-dive" starvation mode, in which any calories absorbed are utilized with maximum efficiency. If feeding meals infrequently is not the answer, and eating whenever you want doesn't work, there must be a happy medium – and there is. Feed enough food for the dog to lose weight, at a frequency that doesn't make its body "think" it's facing starvation. For dogs, twice daily feeding of reasonable amounts of high fiber, low fat dog food is a good approach. Also, treats should be suitably formulated, should be small, and strictly rationed. But even when such measures are engaged, some dogs still don't lose weight.

This is when you should enlist your veterinarian's help. He or she may check your dog for medical causes of weight gain, including hypothyroidism or Cushing's syndrome. Medical problems, when present, should be addressed first. If medical causes of obesity are not involved, a supervised calorie-restricted diet is probably in order. Diets such as Hill's Science Diet® weight reduction ("r/d") and Purina® "OM" overweight management diet are excellent. Purina supplies veterinarians with a computer program so that they can calculate exact daily rations for their patients. This is done by simply plugging in the weight of the dog and the desired rate of weight loss and the computer calculates how much of the ration to feed.

The program limits the dog's weight loss to no more than 4 percent per week to prevent problems associated with overly rapid loss of weight. The essence of weight-loss diets is to provide a proper balance of nutrients while meeting the special dietary needs of the overweight patient. Weight reduction diets tend to be low fat and high fiber. This makes food restriction less psychologically stressful by helping the dog to feel "full."

Medical Conditions and Obesity

The most well known medical cause of obesity is hypothyroidism. It is also the most common genetic disease of purebred dogs, according to the American Kennel Club (AKC). The strange thing is that, though hypothyroidism can lead to obesity, when thyroid levels are restored to normal by treatment, weight does not usually fall off the overweight hypothyroid dog as quickly as you might imagine. For some reason, a weight-reducing diet usually has to be used in concert with thyroid hormone replacement therapy if optimal weight loss is to be achieved in a reasonable period of time.

For dogs with Cushing's syndrome, weight loss is a feature of successful therapy. In such cases, dietary measures are not called for. The overweight appearance of dogs with Cushing's syndrome is partly due to poor abdominal muscle tone, which gives them a pot-bellied appearance. This change is also reversible with appropriate therapy.

Psychological Causes

Just about any psychologically stressful situation can lead anxious dogs to engage in what are called "displacement behaviors." Displacement behaviors include eating, drinking, grooming, chasing, running or walking, and so on. All are natural behaviors but, in this instance, are performed excessively during moments of stress to reduce the impact of the stress or conflict.

If the conflict is prolonged, the displacement behavior can become ingrained. It is as if the neural pathways involved have become well-worn and facilitated. At this stage, the displacement behavior may have reached the proportions of an obsessive-compulsive disorder (OCD) and will be performed out of the context of obvious stress. If the OCD takes the form of excess eating, the dog will gain weight. OCDs are a sad behavioral testimony to earlier or existing chronic, inescapable or unmanageable conflict.

The first rule of treatment is to identify and eliminate all existing causes of conflict and to make sure that the dog has a happy and healthy lifestyle, replete with opportunities for exercise and entertainment. But even if these conditions are met, many dogs continue on their relentless task of either compulsive eating, self-licking, tail chasing, or similar behavior. In such cases, fluoxetine (Prozac®), paroxetine (Paxil®), fluvoxamine (Luvox®), or other anti-obsessional drug therapy, may be helpful. If the diagnosis is correct and the treatment is applied in the correct manner, the weight may practically fall off a compulsive overeater.


Though not a good primary strategy for causing weight loss, exercise can help. Theoretically, dogs and people have to exercise quite a lot to lose even a little weight, yet exercise does help. It provides an outlet for pent-up energies that might otherwise transmute into anxious eating behavior. Exercise also generates increased amounts of a neurotransmitter, serotonin, in the brain. Serotonin has two effects that might be relevant in overeating: First, it helps to prevent anxiety, depression, and has anti-obsessive properties. Second, it reduces appetite.


Losing excessive weight can enrich your dog's life. Even in the early stages of carefully-gauged, well-monitored diet restriction, overweight dogs begin to display changes in temperament and behavior that indicate that they are feeling better. They play more, sleep less, and become more active. It's as if they're saying, "Thank you for rescuing me from my dietary dilemma."