Then, Richie started having heart trouble. A cardiologist told Baruzzi the golden retriever would have a better recovery if he weren’t 20 pounds overweight, and referred the dog to a pet nutritionist.

America’s pets are having their own obesity crisis, studies show, with at least 35 percent of household dogs and cats above their ideal weight. And the nation’s two obesity epidemics — pet and human — are tightly entwined: Americans, it seems, are as indulgent with their animals as they are with themselves.

Linder expects to see a handful of cats and dogs a day while conducting research into pet obesity. The clinic’s standard care package costs $250 for an extensive initial session and six checkups, plus phone and e-mail follow-up, as needed.

Although there are other pet weight-loss clinics ­— and neighborhood vets regularly treat plump animals — few are associated with veterinary schools and staffed by specialists with training in pet obesity and other health problems.

The biggest challenge in addressing pet obesity, Linder and other specialists say, is that most owners are not good judges of their pet’s weight. Nearly 40 percent of owners of overweight pets think their animal does not have a problem, research shows. And veterinarians are leery of pointing out fat cats and dogs, because they do not want to insult the owners.

For most dogs, the best way to identify a weight problem, Linder said, is to touch around the rib cage, which should feel about as padded as the back of the owner’s hand.

For cats, “if there’s a fat pad in the abdomen between the back legs, that cat is overweight,” said Dr. Kathryn E. Michel, medical director and nutrition professor at the University of Pennsylvania School of Veterinary Medicine.

The difference between ideal and overweight for a pet isn’t much. A small cat could be considered overweight if it weighs 10 pounds instead of 8; Baruzzi’s now 100-pound golden retriever should ideally weigh 85.