A. The lump sounds like it could be an occipital hematoma, which is an accumulation of blood under the skin. Hematomas can happen when there has been trauma to the area, such as scratching at the ears or vigorous shaking of the head, or they happen spontaneously. Occasionally, when hematomas recur after draining, they can be an indicator of a blood disorder that prevents normal clotting.

I would strongly recommend that you have the lump drained by your veterinarian and the fluid sent out for analysis. An analysis of the fluid will help rule out the possibility of something more serious, such as a tumor, and help your veterinarian decide how to keep the lump from recurring.

Q. Each year we take our cats to the veterinarian for their annual checkup and inoculations. The last couple of years, it was recommended that their teeth be cleaned because there were signs of redness along the gums. Our cats were not very cooperative. I am wondering if the annual teeth cleaning is so important that we should continue to subject them to the stress and anxiety. Furthermore, I am concerned that the technicians who apply this treatment may not be sufficiently trained. Do you have any advice on this?

A. I have to assume that any veterinarian doesn't want to anesthetize your cats and clean their teeth unless it's medically necessary. But you have every right to ask enough questions about the procedure so that you are comfortable having it done.

Can the veterinarian show you the areas of concern in the cat's mouth? Is there periodontal disease already or are they trying to prevent disease (usually called prophylaxis)? What is the risk involved in doing the cleaning? What is the risk involved with not doing it? Who is going to be doing the procedure and what training have they had? Should you be brushing your cats' teeth in between cleanings, or feeding a different type of food? And of course, how are the cats restrained for anesthesia?

It may reassure you to know that California has very strict laws with regards to who can perform dental procedures. Also, most veterinarians use state-of-the-art equipment that is similar to that used to clean your own teeth. It has become the standard of care to clean our pets teeth annually (some even more often) as we have come to realize the importance of good oral health for our pets overall well-being.

Q. I just got a new kitten. My other cat, who is about 8-years old, doesn't seem to care for the kitten at all. How can I make them like each other?

A. When you first bring a new cat into any household, it's a good idea to designate a "safe room" for the cat. It can be a bedroom, laundry room or bathroom, as long as you can close the door. Provide a litter box, food and water. Visit the new cat frequently for playtime and petting. Your new cat should stay in the safe room until she feels comfortable. She should be eating and drinking and enjoying your company. This may take several days to several weeks. In the rest of the house, pay extra attention to your current cat during this time.

You will be transporting smells back and forth, so that the new animal smell will start to seem familiar to your existing cat and vice versa. You can speed the process by rubbing each cat with a towel and leaving the towel near the other cat's food dishes. Letting them sniff each other under the door or through a baby gate will help as they start to realize "this cat's here to stay."

The first face-to-face introduction should happen in the safe room. Separate them if they immediately start to fight, otherwise allow them to see each other at a distance and eventually sniff up close. After several supervised visits your new cat can explore the house. Leave the safe room available if she gets scared. If at any time the introductions are not going well, it helps to backtrack to the previous stage for a few days. Good luck. Most cats, when properly introduced, can become compatible.

Q. Do I need to vaccinate my cat for rabies if he only goes out in the back yard?

A. We know that skunks and bats carry rabies in California. If there is any chance at all that your cat may come in contact with one of these animals, or with other dogs or cats, he should be vaccinated for rabies. Because of the deadly potential of the rabies virus both to pets and people, this is definitely a vaccine your cat should have. The recent death of a kitten with rabies in San Ramon reminds us that the virus is still present and dangerous.