Who is to blame? The diet, the cat, and the owner. First, most feline diets are higher in fat than an average cat needs. Fat is what makes a food taste good, and cat food companies know that they can only sell their food if cats like to eat it. Second, house cats live nothing like their wild cousins. Wild cats have to exercise to survive, catching 10 to 20 small meals per day. A typical house cat only exercises when he's headed for the food bowl. And third, most owners prefer to feed their cats free choice, because "it's easier to just keep the bowl filled up."

So please, read your cat food bag or can and follow the feeding recommendations. If overweight, your cat should eat the amount recommended for his or her desired weight, not what he or she currently weighs. (Your veterinarian can tell you what your cat should weigh.) Instead of treats, reward your cat with petting, brushing or catnip. Make sure your cat has plenty of daily play time. Even adult cats love to play, they just forget how as they get older and fatter. For some great play ideas see the Indoor Cat Initiative's Web site at http://www.nssvet.org/ici/

And here's a cautionary tale:

A cat recently arrived in our shelter weighing 31 pounds. He looked like a small ottoman. Although I have heard of cats weighing this much, I had never actually seen one.

At this weight he was unable to act like a cat at all. Even though he is very friendly, he would spend his entire day hiding rather than exploring or playing. The slightest exertion caused him to wheeze and look stressed. Moving around or stretching, as cats like to do, was uncomfortable. His skin was flaky so his fur appeared dusty, his ears were dirty, and his coat was unkempt. He was not able to groom himself. If you know cats, you know this is very important to them.

He needed a medically-supervised diet, because rapid weight loss can be dangerous for cats. We began by restricting his daily calories by 5 percent of his calculated caloric need. (We'll readjust as he loses weight.) At first, his exercise plan consisted of walking up a flight of stairs. It also included some serious petting, because purring burns calories, too.

After a couple days, he was able to jump up to a chair, although not very gracefully. It was a big milestone and something he had not done in a long time. Within a week he began to take an interest in play toys which should help him increase his activity.

It took a little longer for him to start to explore his surroundings. With daily activities — exploring, jumping up on things — as well as structured play time, the pounds are coming off. He is delighted to act like a normal cat again, and will soon be ready to find a new home.

Q. My 14-year-old male cat has been losing his hair in large amounts, leaving severe patches of bare skin. It is like the hair is peeling away from his skin. He is severely matted and when I tried to comb them out I noticed the bald spots. Is this serious?

A. At the shelter we often receive cats who are very matted. If the mats are there for a long time, the hair underneath the mat falls out and doesn't regrow, so when the mat is removed there is often a bald spot. If the cat is in good health, the hair should regrow eventually and the bald spot will be gone. But it is important to remove the mats, as the skin underneath can become unhealthy and fragile.

It is also important to consider why the cat has become matted. Cats are normally very fastidious about taking care of their coats, so a cat who is severely matted may have an underlying health problem that is preventing him from grooming himself. Some of the more common causes, especially at your cat's age, could include kidney disease, thyroid problems or diabetes.

I would recommend you have him examined by your veterinarian to rule out any medical causes of the matting problem. If he is given a clean bill of health, your veterinarian may be able to refer you to a professional groomer if you need help removing the mats.