Dear Dr. Fox:

I just read an article about how dangerous clumping kitty litters are. Is this true? Can they cause diseases and block digestive tracts? Last January, I was using un-clumping litter, then I switched to clumping. But then I read this article and now I'm confused.

A.F., St. Louis

The theory goes that clumping litter may get onto cats' paws and be licked off and swallowed, thus causing internal problems. But I have no clear evidence of this being a health risk. The main thing is precaution -- avoid litter that sticks to paws and/or is very dusty, since cats could inhale litter particles while digging and covering their excrement and suffer the consequences.

Also, litter boxes with covers can become ammoniated inside if not kept clean, leading to cats developing an aversion to entering such enclosed boxes, since the foul air plus dirt irritates their respiratory system.

Dear Dr. Fox:

I was interested to read in your column the letter from G.V. in Washington, D.C., about the golden retriever who collapses, then gets up after a few seconds.

Our 15-year-old peekapoo had the same symptoms. The vet X-rayed her and discovered a huge tumor on her heart, taking up almost the entire chest cavity.

Perhaps G.V.'s vet should X-ray their dog as well. Unfortunately, our dog had to be put down, but perhaps theirs can be helped.

N.C., Tryon, N.C.

There are many reasons why animals suddenly collapse, and even if the animal seems fine after the first time this occurs (other than obviously slipping on a smooth surface and having difficulty getting up), immediate veterinary attention is called for. Brain, spinal cord, heart/circulation, and other organ and system disorders (especially in older animals) can cause sudden collapse, incoordination, and muscular tremors and weakness. Repeated episodes in younger animals could be due to other factors such as low blood calcium, adverse drug or vaccination reaction and even poisoning.

Animals so afflicted may show fear or panic, but pain may not be evident. Even so, it is an emergency situation and a "let's wait and see if she's better tomorrow" attitude is unacceptable.

Dear Dr. Fox:

I have an 8-year-old yellow Labrador dog who has developed a urine leakage problem. His bed will be wet in the morning and he leaves spots wherever he's been lying. Our vet has given him shots of testosterone, which takes care of the problem for about a month. We've tried to cut down the frequency of the shots, but the problem recurs in about seven weeks.

Is there anything else we can do? He's a very active dog.

J.H., Buffalo, Minn.

Urinary incontinence is rare in male dogs compared to neutered females. The testosterone replacement therapy may help, but it can have harmful side effects if not carefully monitored.

Be certain that the veterinarian has ruled out prostate disease, infection, calculi (stones) and cancer in your dog's urinary bladder. All those problems can make a dog incontinent and want to urinate more frequently, as can chronic kidney disease and diabetes, which are very common in older dogs who compensate by drinking more water.

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.