by Melinda Felming, DVM

"Obesity is the most prevalent form of malnutrition in veterinary medicine" (Elliott) and it is a rising problem in cats.  "Obesity" is not often the first word that comes to mind when mentioning malnutrition.  However, obesity is one of the most common problems in cats being evaluated by a veterinarian.

There is a difference in the terms "overweight" and "obese."  The body weight of overweight cats is more than 10% above their ideal body weight.  Obese cats have a body weight that exceeds 20% of their ideal body weight.  Obesity begins with being overweight and can occur very stealthily.  The success of prevention and treatment of obesity relies partially on the recognition of the most common factors that could put your cat at risk.

As you will see, there are several things to consider when determining whether your cat may be prone to becoming obese.

The majority of obese cats are those belonging to the class referred to as the "domestic" breeds (domestic shorthair, etc.).  While there is some suggestion that pedigreed cats like the Siamese may have a genetic influence for being lean, there are enough cases of these and other pedigreed cats becoming obese that this cannot be assumed to be true 100 percent of the time.

The risk is greatest between the ages of five, and 10 to 13 years.  It decreases after that.

Castrated and spayed cats are both at risk for developing obesity, with males having a greater risk than females.  "It should be emphasized that the age of the cat at the time of surgery has no effect on the development of obesity." (Diez, Nguyen)

This is a major risk factor for cats, especially indoor cats.  They will spend the majority of their time sleeping, grooming, and eating.  They typically get little or no exercise.

Some drugs lead to increased appetite and, secondarily, excess body weight.  These include anti-seizure, corticosteroid, and contraceptive medications.

Several factors are involved.  They include the type of food, not taking into consideration the cat's energy needs, feeding free choice, fatty supplements, and treats from whatever the owner is eating.  These are all culprits in the development of obesity. 

Cats have no need for social interaction during feeding times.  However, many owners equate feeding their cat as a means of communicating with their pet.  "Owners of obese animals interpret any demand from the animal as a demand for food" (Diez, Nguyen), when it may in fact be sufficient to play with the pet or brush and stroke it as a means to provide attention.  However, once the cat associates initiating contact with receiving food it is difficult to alter this behavior.  These cats can be quite insistent if they do not receive their food reward.

If only one or two cats are in the household there is an increased risk for one or both of them to develop obesity.  However, cats in the household with dogs were not as much at risk, and three or more cats in a household decreased the risk as well.

Obesity is significant due to its role in leading to the development of several diseases, and the ability to worsen pre-existing disease.

The occurrence of this disease has substantially increased over the last few years.  This may be directly related to the higher prevalence of feline obesity, which is directly associated with the body's ability to use insulin.

Also known as "fatty liver," the hallmark of this disease is an overabundance of lipids (fat building blocks) in the liver.  It is one of the most common liver disorders of cats, and obese cats are more likely to suffer from this disease which can be fatal.

Because the cat cannot groom appropriately and is probably eating an unbalanced diet, the skin can become flaky and oily.  The hair can become severely matted which can cause discomfort and skin infections. 

Obese felines are not as interested in breeding as cats of healthy weights.  If the queen does conceive she may not maintain the pregnancy.  In addition, too much weight gain [in an already compromised obese cat] may contribute to a difficult birth and decreased number of live kittens at birth.  The birth canal can be too narrow for the kittens to pass through due to accumulation of excess fat. 

Conditions which already exist, such as heart and lung disease, and arthritis, are greatly exacerbated by obesity.  There are also other concerns with an obese feline patient.

Because of restricted breathing due to fat accumulation in the chest and decreased chest capacity, these patients are at a greater risk if anesthesia becomes necessary.

Obese cats are prone to developing pressure sores due to their sedentary lifestyle.  Sores can also occur on the hindquarters secondary to development of large folds of fat here.  Combined with the inability of the cat to groom and clean this area, severe scalding and ulceration of the skin by urine and feces occurs. These cats are also more likely to have complicated or delayed healing following surgery.

Treatment begins with the owners not only recognizing that their pet is obese, but realizing that there are serious health concerns for the obese feline.  The cat should be evaluated by a veterinarian who can perform tests to determine if there are other diseases occurring simultaneously which will require therapy.  An appropriate weight loss program can then be developed to ensure a slow and controlled reduction.  This is especially important in obese cats due to the possibility of their developing fatty liver disease.  While treatment will be prolonged, a successful resolution is not impossible with commitment and patience.

In the case of the obese feline, an ounce of prevention is truly worth a pound of cure.  Knowing the risk factors associated with obesity in cats and regular monitoring by your veterinarian will help your pet to avoid developing this disease and the associated complications. 

References available on request.