Nationwide surveys suggest that as many as one dog or cat in four seen by veterinarians is overweight or clinically obese.
"Feeding too many calories is much more prevalent in the pet population of Western societies than all other nutrient deficiencies combined," says William Burkholder, a clinical nutritionist at the Texas A&M University College of Veterinary Medicine's Veterinary Teaching Hospital, and one of only a handful of board-certified veterinary clinical nutritionists in the United States.
Overweight pets are not just academically interesting to veterinarians, Burkholder says; they are more likely to suffer from other diseases much like overweight humans. "Dogs and cats do not get coronary artery disease because they eat too much fat. Their metabolisms don't work that way," Burkholder says. "But fat dogs can get hypertension and congestive heart failure because they are overweight, and fat cats are predisposed to diabetes and fatty infiltration of the liver, which can be deadly."
Carrying too much weight may also increase the severity of hip, back and knee problems. "Diagnosis of joint disorders is often what brings an animal's weight to the veterinarian's and owner's attention," he says.
"Pet dogs and cats add excess pounds as easily as people for many of the same reasons—too much food and too little exercise," Burkholder says. "And pets can lose weight the same way people do—eat less and exercise more."
Burkholder suggests owners of overweight pets enlist their veterinarians' help to set up a weight reduction program. Working with a specialist trained in veterinary nutrition may help in some cases, but it's not essential.
"Specific reductions in calorie intake should be based on individual animals' needs," Burkholder says. Cutting back an animal's food by 20 to 30 percent is not uncommon. However, reducing calories alone may not be enough.
"They won't lose weight until you start them on some sort of persistent daily exercise," Burkholder says. "We're not talking about making athletes out of them, just 20 to 60 minutes of persistent daily leash-walking."
Patience may be one of the most important ingredients in trimming your pet down to its ideal weight, Burkholder says. Observation and rechecks for as long as six or 12 months may be necessary to get an animal back to its ideal weight.