Obesity & Weight Loss
What is obesity?
Obesity is defined as weighing 30% more than the ideal weight. With humans, this is fairly straightforward and can be determined by consulting weight and height charts. Dogs and cats are often diagnosed as obese by a combination of weight charts and body scoring.

Is feline obesity a problem?
YES – obesity, defined as an excess of body weight of 30% or more, is the most common nutritional disease of domestic cats. Although the frequency varies from one country to the next, on average up to 40% of all adult cats are obese! Despite these alarming figures, very little is known about the detrimental effects of obesity on feline health. Obesity in cats is a known risk factor for type 2 diabetes mellitus, heart disease, osteoarthritis, certain forms of cancer and lower urinary tract disease. In humans, obesity causes an increase in morbidity and mortality at all ages and is associated with diabetes mellitus, certain types of cancer, impaired mobility and arthritis, high blood pressure, heart disease, and other illnesses. Recent studies suggest that heart disease also develops in obese cats! More research is needed to evaluate this and to determine what other detrimental effects obesity has on cats.

Obesity in cats is associated with hepatic lipidosis. This is a severe form of liver failure in cats. It typically occurs in cats that are obese and have undergone a brief period of “stress” which causes anorexia. The “stress” may be as simple as a change of house or a change in diet. When it first became recognized, Hepatic lipidosis was an almost universally fatal disease in cats. Fortunately, with improved, aggressive and prolonged therapy about 80% of affected cats can now be successfully treated. However, because of the risk for this potentially fatal disease, weight loss programs for obese cats need to be done cautiously and always under the care of a veterinarian.

I had my dog neutered. Do you think this caused the problem?
It is very unlikely that neutering caused your pet’s weight problem. There is no scientific research that concludes that neutering causes obesity in dogs.
My dog can’t be obese because he only eats a small amount of food every day.
Obesity often develops insidiously. We think we are feeding our dogs only small quantities of food but tend to forget the treats and table foods. These treats add calories and result in weight gain. Even a few calories can add up over time.

What causes obesity in cats and how should it be treated?
Many factors contribute to obesity in cats, and not all of them are clearly understood. Some are probably genetic, while others are related to diet and environment. It is important for the cat owner and veterinarian to keep these factors in mind when treating the obese feline patient. Prevention is better than treatment, but this is not always easy. Indoor cats are more prone to obesity, perhaps because they eat more out of boredom, but also because they have less opportunity to stay trim through exercise. Remember that everybody should run and play, including cats!

Once a cat becomes obese, the challenge for owner and veterinarian alike is to safely promote weight loss to reach optimum weight. In the long run it is better to set realistic goals for weight reduction rather than attempting to force the cat down to a “normal” weight. Usually a 15-20% reduction in weight is a good target that can easily be achieved! Rapid weight loss should be avoided, since it puts the cat at risk for development of severe liver disease. Weight that is lost slowly is more likely to stay lost! There are no drugs or magic pills that can be used safely or effectively. Commercial “restricted-calorie” and weight loss diets are available from veterinarians and provide the basis for a successful weight loss program. However, they are more effective when combined with additional exercise. This also has the advantage of providing more time for interaction between the cat and the family, which we know provides enjoyment and is beneficial for the health of both. With some patience and extra care, obese cats can be treated safely and effectively, with the ultimate goal of prolonging a healthy happy life!

What can I do for my dog?
With today’s advances in nutrition, weight loss has never been easier. Your veterinarian will design a safe and effective weight loss program to meet your dog’s lifestyle. Encourage brisk, thirty-minute walks twice daily. Discontinue feeding table foods and treats. Instead, offer carrots, broccoli or veterinary-approved low-calorie treats. Most pets can lose weight if you adhere to these recommendations. Weight loss in pets and humans is made up of an interaction between reduced caloric intake (eating less) and increasing caloric expenditures (more physical activity). The great news is that weight reduction is about 60% diet and 40% exercise. Weight loss is often a matter of diligence and persistence. Remember that the reason you are doing this is to help your pet live as long and healthy a life as possible My dog is losing weight and I don’t understand why? Weight loss in dogs may be associated with many normal and abnormal conditions. Weight loss is considered to be clinically significant when it exceeds ten percent of the normal body weight and when it is not associated with fluid loss or dehydration. For example, a healthy Golden Retriever weighing a breed-normal seventy pounds would have to lose over seven pounds before the weight loss would be considered clinically significant. Changes in diet, environment, or stress levels, including the addition of new pets, may lead to weight loss that is rarely permanent or significant.

Weight Loss

What causes my dog to lose weight?
Weight loss is the result of insufficient caloric intake relative to the body’s requirement. This may be caused by:
  • High energy demand associated with excessive physical activity or a hypermetabolic state
  • Inadequate or poor quality diet
  • Insufficient quantity of food intake associated with anorexia, swallowing disorders or regurgitation
  • Malabsorption and/or maldigestion disorders
  • Excessive loss of nutrients or fluid from vomiting, diarrhea, or excessive urination
What other signs should I look for?
Weight loss can affect any of the body’s organ systems. Questions that may provide insight into the cause of your dog’s weight loss include:
  • Is your dog’s appetite normal, increased or decreased?
  • Does your dog have a fever?
  • What kind, when, where and how much dog food are you feeding your dog?
  • How and where do you store your dog food?
  • How often do you administer your dog’s heartworm preventive and what type of preventative do you use?
  • Have you observed any regurgitation or vomiting, diarrhea or loose stools, or changes in water consumption or urination?
  • What color and consistency are your dog’s stools?
  • Has your dog been spayed or neutered?
  • Have you noticed your dog having any trouble swallowing?
What are some of the common diseases that cause weight loss?
There are many diseases that can cause weight loss. In fact, most chronic diseases will result in weight loss at some time during the course of the disease. However, some of the more common conditions associated with weight loss include:
  • Anorexia due to a behavioral condition or disease
Pseudoanorexia caused by loss of smell, inability to grasp or chew food, swallowing disorders, vomiting or regurgitation
Malabsorptive disorders that inhibit the body’s ability to absorb nutrients from the intestinal tract such as infiltrative and inflammatory bowel disease, lymphangiectasia, or severe intestinal parasitism
Maldigestive disorders that interfere with the body’s ability to break down food into usable nutrients. The most common condition is exocrine pancreatic insufficiency. Metabolic disorders such as diabetes mellitus, hypoadrenocorticism (Addison’s disease), hyperthyroidism (rare in dogs, common in cats), and cancer.
  • Diseases involving the major organs (heart, liver or kidney)
  • Neuromuscular disease resulting in weakness or paralysis
  • Swallowing disorders
Central nervous system disease causing depression, anorexia or pseudoanorexia.
Increased caloric demand associated with excessive physical activity, prolonged exposure to cold, hyperthyroidism, pregnancy or lactation, fever, infection, inflammation and cancer.

What can be done to diagnose the cause of my dog’s weight loss?
A thorough medical history and physical examination will help your veterinarian determine the most useful diagnostic tests to perform. Blood and urine tests and radiographs are the most commonly recommended diagnostic tests.

What can be done to treat my dog’s weight loss?
Treatment will be determined by the specific cause of your dog’s weight loss. Once a specific diagnosis is made, treatment to improve your dog’s quality of life will be immediately initiated.

What is the prognosis for my dog’s weight loss?
The prognosis ranges from grave to excellent depending on your dog’s specific diagnosis. A thorough medical history, complete physical examination and appropriate diagnostic testing will assist your veterinarian in determining the best course of treatment for your pet.


Rosswell Animal Hospital, Ontario, Courtice

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Rosswell Animal Hospital, Ontario, Courtice

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