CVMA-ACMV

Loss of Weight and Body Condition in Senior Pets

July 23, 2007

Better veterinary care, home care, nutrition, and treatment of medical and surgical problems in senior pets have all contributed to the explosion of the “senior set”!

The average lifespan of pets continues to increase as new discoveries lead to an expansion of knowledge about pets in their golden years. We continue to learn that measures taken by pet owners and veterinarians earlier in a pet’s life can significantly impact the pet’s health in the senior years.

Age is not a disease, but is a complex process that causes many changes in the body. These changes are often inter-related, and usually occur in a slowly progressive fashion. One of the important signs of aging to look for in your geriatric pet is a loss of weight and body condition.

Body condition refers to the overall balance of lean tissue (muscle) and fats, and how well these tissues cover the normal skeletal structure. Veterinarians use a number of scoring systems to classify an animal as obese, over-conditioned (overweight), normal weight, trim fit, and cachexic (extremely thin and wasted). Some of the scoring systems may use different terms, but all help us assess the degree to which a pet is “filled out” or not. This system is different than just measuring the number of pounds or kilograms a pet weighs because it takes into account the different body frame sizes of individual animals. For example, a large-framed male dog may weigh more than a smaller, less heavily-built bitch of the same breed and age, but they may have the same body condition.

Weight loss can occur in different ways and results in a loss of body condition. Proportions of lean and fat tissues lost will vary depending on the cause of the weight loss.  As an example, many cancers tend to produce serious weight loss. These illnesses unfortunately don’t just trim the tummy! Tumors release specific factors that tend to cause both fat and muscle to be burned up during the disease. The nutritional (and metabolic) needs of senior cancer patients can be very high indeed.

Normally, appetite and thirst become weaker with age. The efficiency of digestion also drops off as an animal gets older. Add to this a disease process that either interferes with chewing, food absorption, processing, or storage, or that causes nausea, chronic pain, or mental dullness leading to loss of a healthy appetite, or arthritis that prevents normal mobility in order to reach the food dish, and you have a recipe for a thin senior pet!

The tendency for reduced food intake, combined with reduced activity of a normal senior, or especially an ill senior pet will lead to muscle wasting due to reduced use of the limbs, as well as lost muscle mass due to reduced intake of the building blocks needed to maintain a healthy muscle mass.

Chronic kidney diseases and hyperthyroidism are other common conditions in  senior cats that will lead to loss of body condition / weight.

Diabetes, dental disease, chronic constipation, and arthritis are other common conditions that may lead to weight loss problems.

Sometimes the cause for loss of weight loss or poor body condition in senior pets is not obvious, and requires a diagnostic work-up. Though geriatric pets tend to be thinner (less filled out) than adults and juveniles, serious weight loss or poor body condition tends to reflect diseases that are developing on top of the aging process. If your notice your senior pet losing weight and body condition, see your veterinarian for a professional assessment.