Dear Dr. Fox:

My 4-year-old longhaired apricot tabby, Roxy, has developed a rapidly growing cancerous tumor on her right rear leg. It has gone from the size of a grape to the size of a baseball in just four weeks. I'm told the only option is to amputate the leg, which I am not really in favor of as there is no guarantee that this will cure her. I would really hate to put her through that if it won't cure her.

The vet told me that it could have been caused by her rabies vaccination. How common is this? If I get another kitten sometime in the future, how will I know it won't happen again?

L.T., Alexandria

I am sorry to hear about your cat's affliction, which could, as your veterinarian suggests, be the result of an injection. Cats can develop this kind of cancer following a rabies vaccination or other injection, and the only treatment is, indeed, amputation. And there is no guarantee that the cancer has not already spread to internal organs. Chemotherapy may or may not help after the leg is amputated.

Some veterinarians advise giving only the canary pox vectored rabies vaccination to cats -- it's considered safer than other types. Also, injecting the vaccine under the shaved skin one-third of the way down a cat's tail may be preferable, because if cancer develops at the vaccination site tail amputation would be less traumatic and less costly.

Dear Dr. Fox:

I have a 6-year-old male Pekingese dog. We got him when he was 4 years old. We discovered that he gets seizures -- about one every six months. My vet knows about this and says it is fairly common.

But now Pooh Bear is getting these attacks at least five times or more a week. He has stiffness and muscle spasms. We took him to the vet and he was put on 3ccs of lactulose/Enulose twice a day, but it doesn't work. How can we help Pooh Bear with this problem?

S.A.P., Glenville, N.Y.

The veterinarian treating your dog must have diagnosed a condition called portosystemic shunt in order to prescribe lactulose/Enulose to help alleviate your dog's congenital disease.

This disorder (which, in some cases, can be surgically corrected) is caused by ammonia and other toxins coming from the liver through a circulatory defect, and leads to impaired brain function and a host of health problems. But your dog should also be put on a special diet low in animal protein and high in vegetable protein and easily digested carbohydrates like white rice and pasta.

Since this additional treatment (coupled with oral antibiotics) is not mentioned, and therefore presumably not prescribed, you should seek a second opinion. Your dog could simply be epileptic and have fewer seizures once an appropriate dosage level of phenobarbital or other anti-seizure medication is determined.

Dear Dr. Fox:

I have a large dog that has digestive problems. Sometimes she won't eat unless she goes out and chews the tops of fresh grass. Later, she will eat. What makes her want the grass?

E.C., Freehold, N.J.

Grass-eating is part of a dog's natural behavior, and possibly reflects some inborn nutritional wisdom that warrants scientific study. Of course, dogs also eat grass when they are feeling sick, but the quiet, deliberate "grazing" of healthy dogs like mine (who enjoy eating a dozen or more blades of grass -- un-regurgitated -- many mornings before they are fed) does raise the question of why. My theory is that grass stimulates the digestive system and is a tonic, and that it also possibly contains beneficial nutrients the way wheat grass juice and barley sprouts do for humans.

So let your dog graze a little. In this instance, I believe that nature knows best.

Dear Dr. Fox:

I have a cat named Old Tom. My doctor says I can't eat egg yolks anymore, and I try not to, but when I fry eggs Old Tom meows at the door.

Are the yolks hurting Old Tom (he's only 4)? I can almost see him smile when he gets the yolks that I can't eat anymore.

J.F., Granbury, Tex.

All things in moderation for man and beast alike! Give no more than one egg yolk daily (lightly cooked) or two every other day to Old Tom.

Egg yolk is a complete source of protein and good for cats, but caution with older cats and cats with kidney disease is called for. Unlike human beings, cats do not develop atherosclerosis from elevated "bad" cholesterol.

Cooking with olive oil or sesame oil will help lower your cholesterol and will give Old Tom a shiny coat!

Michael Fox, author of many books on animal care, welfare and rights, is a veterinarian with doctoral degrees in medicine and animal behavior. Write to him in care of United Feature Syndicate, 200 Madison Ave., New York, N.Y. 10016. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

(c) 2004, United Feature Syndicate Inc.