Dr. Dan Christian specializes in small animal medicine, with special interests in behavior and nutrition. He has been instrumental in establishing animal behavior residencies for veterinarians at leading veterinary schools and developing innovative programs with veterinary organizations in the United States. He is a member of the American Veterinary Medical Association, the American Animal Hospital Association, and the Southern California Veterinary Medical Association. During his professional career, Dr. Christian earned the American Association of Feline Practitioners Award. He has also appeared as a guest on television and radio pet health programs nationwide, and to has authored numerous articles for pet health magazines.

Q: My cat Sam is 16 years old. He is a red tabby and has been in excellent health. He has been a house cat his whole life. He is still playful and has a good appetite. However, he seems to be much thinner than he used to be and I was wondering if it is normal for cats, especially at his age, to start losing weight or if he may have worms or some other medical problem? His habits have not changed. He has slowed down, but is still active.

A: Weight loss in senior cats is fairly normal, and at 16 years of age, the gradual weight loss that occurs with the aging process now is obvious. You are correct that it can be a normal physical change; muscle mass decreases, in large part due to overall decreased use of muscles as cats gradually slow down and become less active.

You will, however, want to make sure Sam does not have any underlying conditions that are contributing to the loss in weight. I recommend all cats over 12 years of age get a good physical examination from a veterinarian twice a year. Blood tests to check for thyroid levels, blood glucose levels, as well as kidney and liver function, should all be part of the exams, as should dental checks. If there is any indication any of these or other parameters are askew, your veterinarian can step in for early treatment recommendations to help prolong Sam's life and keep him healthy.

From a nutritional standpoint, be sure to continue feeding a high quality diet, both wet and dry food, to ensure adequate protein and fat levels, which will help maintain his physiology and his health. If all the blood parameters are normal, keep doing what you're doing for Sam -- it sounds like he has a wonderful home. Congratulations on your good fortune of being together for 16 years, and we hope for many more healthy years for you both.