Aside from routine preventive care, the No. 1 reason cats are taken to a veterinarian is for what's called feline lower urinary tract disease (FLUTD).

Missing the litter box is a classic symptom of this serious illness. Yet many people don't recognize the fact that a cat is sick, and they sometimes resort to punishment (which not only doesn't work on a sick cat, but is also grossly unfair). Cats with FLUTD may also be observed straining or crying in pain when they urinate, and that urine can smell "different" even to the human nose.

The disease can turn up in any cat but tends to hit middle-aged, overweight pets most. Stress may also be a contributing factor, which is why the problem sometimes turns up when cats are moved to a new home or when new people or pets join the family.

Litter box problems often mean a sick cat, not a bad one. Keeping cats from becoming obese and encouraging them to drink more can help prevent problems, as can offering smaller meals and more play to relieve stress.

Cats with chronic urinary tract issues may benefit from a special diet. In any case, a veterinarian's advice can help keep a cat from contracting this top feline health problem and keep it from coming back when it does.