My Boston-Chihuahua cross has recently lost his appetite. He is 18 months old, and he used to eat everything as fast as he could, but lately he hasn’t been eating his food with the same enthusiasm. Should I be worried?

Abby Vancouver, BC, Canada

Several times each week clients express concern to me that their pet’s appetite is not what it used to be. In fact, it happened three times today alone.

Loss of appetite is a symptom of a number of serious diseases, including problems with the kidneys, liver, and pancreas. Cancer and poisoning also can cause loss of appetite. However, these syndromes usually cause other symptoms as well, such as weight loss, lethargy, vomiting, diarrhea, or increased thirst. And, with the exception of poisoning, they are rare in young animals.

In the case of your dog, I suspect nothing is wrong. Young growing puppies and kittens naturally need much more food, on a pound-for-pound basis, than adult animals. Therefore, most puppies and kittens are continuously hungry. As they reach adulthood, their metabolic needs decrease, and so should their appetites.

There is a very simple measure of whether your pet’s appetite is adequate: his weight. Simply put, if his weight is stable or increasing, he is eating enough. If his weight is decreasing, he isn’t. This applies to all healthy animals, except those on diets.

Most veterinary offices will be happy to weigh your pet, free of charge, any time. If that is not convenient, a slightly less accurate method is to hold your pet and step onto your bathroom scale. Subtract your own weight (try to be honest), and what’s left over is your pet’s weight.

Keeping track of your pet’s weight will give you insight into whether his appetite is adequate, and also can help prevent another major problem among pets: obesity.