Cats suffer from a host of ailments--including fatty liver, heart disease, diabetes, and kidney failure--that are brought on, at least in part, by what their humans feed them, or don't. "Cats are obligate carnivores," MacArthur says, "which means they can't make the things they need from scratch and can't get them from plants. The nutrients that they need are available only in meat."
Commercial cat foods, which generally contain too many carbohydrates and not enough protein and moisture, are often the culprit when cats show up with diet-based health problems. But occasionally owners who are vegetarians or vegans want their pets to follow suit.
"You have to convince them that cats are different biochemically, and the values you impose on yourself can't be imposed on this creature," MacArthur says. "For the most part, they're relieved and very receptive to it. Some are sheepish. But if they're responsible enough to come here, they're responsible enough to do what we tell them."
The word seems to be getting out. "I would say years ago I saw more," says Barbara Butman of Easthaven Animal Hospital. "I think now people are more aware, they're more careful in general about what their animals eat."