Dear Dr. Fox:

I have an Australian shepherd who has a great personality -- she doesn't bark, and all in all is a perfect dog! But she has a problem with digging large holes and I can't break her of it.

I tried squirting her with water, but she loves water. I bought No Dig spray -- she just moves to another spot. My husband says we should fill in the backyard with cement. We have a large, fenced yard, so I really don't want to tie her out. Can you help?

B.S., Saginaw, Mich.

Dogs dig for fun, because they are bored or because they want a cool spot in which to lie.

One solution is to dig up the ground, put galvanized chain-link fence about one foot deep, cover it over with soil and reseed. Another is to place balloons in your dog's holes and cover them up -- the next time she digs she'll get scared when the balloons burst and she'll stop this activity.

Alternatively, give her a fenced area to run and play in, using layers of sand, crushed rock and pea gravel on the ground, with a kennel and shaded area at one end of the enclosure. Astroturf is a good surface for a dog run -- it can easily be hosed clean and will be difficult for your dog to dig through.

Dear Dr. Fox:

When I take my cat for her annual checkup, the vet performs a feline titer that determines the level of antibodies in the blood and whether the cat needs shots. The titer costs around $50, adding considerably to the cost of an annual checkup.

Why is this test necessary? Isn't the length of immunization known the way it is with humans, e.g., a tetanus shot lasts for x-number of years, and so on? Is it necessary to perform this costly test every year?

P.D., Columbia

The fact that your animal's doctor is doing antibody blood-titer determinations, rather than simply giving your cat a "booster shot," is to be applauded. Don't quibble over the price -- it's worth it, considering the potential risks of most feline vaccines that are needed (especially for cats who go outdoors), but that do not need to be given every year in most instances.

Some animals do not have a good response (i.e., producing a protective level of antibodies) to some vaccines, or have a short-lived response. So routine blood-titer tests are called for rather than annual re-vaccinations across the board.

Dear Dr. Fox:

My 10-year-old male cat has been chasing his tail, hissing and growling. This has been going on for about six months. At first I thought he might be plugged up, but he has been going to the bathroom with no trouble.

He is very aggressive. Last May, he was asleep on my lap and as I was pushing him off he attacked me -- bit both my arms. I got an infection and had to go to the doctor twice because the infection wouldn't heal and my arms looked like I'd been in a catfight.

He has been neutered and his front paws are declawed. My doctor suggested that we put the cat to sleep, but my husband wouldn't hear of it.

I talked to my vet about this, but he doesn't seem concerned. We've had the cat since he was 5 weeks old.

I buy Meow Mix -- it seems this is the only food he likes. He won't eat canned food.

Do you have any suggestions?

M.G., Swartz Creek, Mich.

Your cat's seemingly psychotic behavior is extremely serious considering his evident distress and suffering, and your emotional and physical trauma and potentially serious bite wounds.

Your cat's anal glands need to be checked and the tail X-rayed for possible fracture (after accidental trapping in a refrigerator or other door, which might have gone unnoticed).

Take your cat to a veterinarian who shows more concern for a full physical checkup. Some cats suffering from hyperthyroidism can go a little crazy and become aggressive, so his change in behavior and aggression need to be taken very seriously.

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) 2005, United Feature Syndicate Inc.