It has been estimated that at 25 to 33% of cats are either overweight or grossly obese, with the highest rates seen in middle-aged
cats. Yet the 2003 AAHA Compliance Study (The Path to High-Quality Care) found that veterinarians are significantly under diagnosing feline obesity. Owners also may not recognize when their cat
is overweight, nor be aware of the associated health risks. Obesity should be the easiest disorder to diagnose, but it is
also one of the hardest to treat.
Obesity is a multifactorial problem with many influences. Endogenous factors include age, gender, reproductive status, and
possibly genetics. Exogenous factors include exercise, type of diet (including palatability) and caloric intake, frequency
of meals, environment and lifestyle. In recent years, research has focused on the role of adipose tissue in the process of
obesity. Adipose tissue is an endocrine organ, secreting many proteins, hormones and cytokines, such as leptin. More research
is needed in cats to define the role of adipose tissue in both health and obesity.1
A link between gonadectomy and obesity in the cat is well known. Research has shown that altered male cats require 28% fewer calories than do intact male cats, and altered female cats require 33% fewer calories
than do intact female cats.2 Free access to food after gonadectomy is likely to result in excess weight gain. Remember to counsel cat owners at the time
of gonadectomy about the need to adjust food intake in the months after altering. It is much easier to prevent obesity than
to treat it!
In a recent study of 385 urban cats in France, 19% were found to be overweight and 7.8% to be obese.3 Similar to other studies, male gender, neutered reproductive status, and underestimation of the cat's body condition by
the owner were identified as risk factors for being overweight. In contrast to other studies, confinement and living with
no other animal did not appear to be significant as risk factors. Pedigreed cats and especially longhair cats were associated
with a lower risk for obesity.
Cats reach their adult weight by about 1 year of age. Certain large pedigreed breeds, such as the Maine Coon, may take up
to 2 years to reach mature adult size. Looking back in a patient's medical record for the weight at about 1 year of age is
one way to help estimate ideal body weight.
Cats are considered overweight when they are 10% above optimal body weight, and obese when they are 20% or more above optimal
weight. For many of our feline patients, control of obesity is a life-long issue. Weigh your feline patients at every visit
and record the body condition score (BCS), using a chart such as the Purina 9-point Body Condition System. Cats are considered
obese at a BCS of 6.3 or greater on a 9-point scale (3.5 or greater on a 5-point scale). Another excellent system is the Waltham
Feline Body Mass Index, which provides a simple method for measurement of body fat.4 Quantifying obesity is the first step to help both you and the owner recognize the problem. If an increase in weight has
occurred since the last visit, calculate the percentage weight gain. Owners may be more able to appreciate the significance
of weight gain when it is expressed as a percentage, and also when trends are tracked over time on a graph or chart.
Substantial health risks are associated with excess weight gain in cats. Obesity in cats is known to be associated with diabetes
mellitus, hepatic lipidosis, lameness, nonallergic skin disease and other health problems.5 It is important that both owner and veterinarian recognize that obesity is the most common nutritional disorder in feline
medicine and that it has serious consequences.
There are four components to a successful weight loss program for cats:
• Dietary change
• Environmental modification, including increased exercise
• Client education and compliance
• Support and follow-up from veterinarian and staff
