Q: Our dog finds our cat's litterbox irresistible. It's a disgusting habit, and we can't break her of it, even with spankings and yelling at her. It just makes her sneakier. Have you ever written about this? What can we do? — K.I., via e-mail.

A: We get this question constantly. Litterboxes are irresistible to many, if not most, dogs: They're drawn to the undigested protein that remains in feline feces. Faced with a constant supply and ready access, no dog will be able to resist for long, which is why efforts to train your pet haven't been successful.

The better plan would be to restrict access, which can be accomplished in one of three ways:

1. Use covered litterboxes: You can find litterboxes with lids at almost any pet-supply store, and this might fix the problem. Cats who have asthma shouldn't use them, some cats won't use them, and some dogs are strong enough (or small enough) to get to the box anyway. But, for some households, a covered box will solve the problem.

2. Change the litterbox location: Make any change slowly, so you don't discourage litterbox use by your cat. But it doesn't hurt to experiment with moving the litterbox to a location above the dog's reach.

3. Provide barriers: One way is to rig a door so it stays open wide enough for the cat but not for the dog. One way to accomplish this is by putting hooks on the edge of a door and the door jamb, and then by putting a length of chain between them to allow the door to stay open wide enough for the cat, but not for the dog. Another possibility is to cut a cat-sized hole through the door to the litter box room. For a small dog who's able to fit through any opening a cat can, a baby gate is an alternative. The cat can jump over it, but the dog cannot.

Experiment with what works, and realize that punishment doesn't work when the reward is as wonderful (to your dog) as what's in the litterbox. This is one case in which training the family to make adjustments usually works much better than trying to train the dog.

This article was written by a Veterinarian.