Dear Dr. Fox:

I'd like to know if flat white worms can hurt dogs. Our vet says they don't. Both of our dogs have them, and I saw one about a half-inch long come out of one.

D.W., Dinuba, Calif.

I am amazed by your complacency, and I wonder, when you saw worms crawling out of your dogs, why you didn't seek immediate veterinary treatment.

From your description, I surmise you're seeing mobile tapeworm segments. They are full of eggs that eventually will be eaten by developing flea larvae in dirty carpets and on the ground, especially in the cracks between floor boards. They stay dormant inside fleas, and when a dog catches and swallows a flea, the tapeworm eggs develop quickly and attach to the dog's intestinal wall from which they feed, drawing nutrients from the dog's digestive system. The tapeworms grow quickly and produce segments filled with eggs (through self-fertilization) that pass out in dogs' stools or crawl out of the rectum.

Your dogs must be treated for both tapeworms (which can occasionally cause severe intestinal blockage and feed off of your dog, robbing the animal of essential nutrients) and for fleas (to break the tapeworm cycle). Cats can be infected, too, but not humans. Young animals are especially prone and often develop nutritional problems, notably stunted growth and rickets.

Dear Dr. Fox:

After dealing with stool-eating for years with my golden retriever, I realized that eating stool was Molly's desperate search for stomach enzymes that her body didn't produce in great enough quantities.

I started adding a generous tablespoon of active plain yogurt to each meal. The stool-eating stopped almost immediately. After I finished the large container of yogurt, I would sometimes forget to replace it and, within two to three weeks, she'd be back to eating stool. I'd start the yogurt again and the stool-eating would stop.

I've also used various combinations of digestive enzymes sold through pet supply companies and had success with them as well, but the yogurt was much cheaper and Molly loved the taste. I've passed the yogurt tip on to several friends and, in each case, the stool-eating stopped.

M.B., High Point, N.C.

Thank you for your remedy for coprophagia that may work for some dogs but not all, to which other letters on this topic attest.

Your effective cure supports my theory that many poop-eating pooches are suffering from a nutritional deficiency. The fact that when your dog stopped receiving yogurt her coprophagia returned is clear evidence that dogs in this category (of an as-yet-to-be-determined nutritional deficiency) benefit from a highly nutritious supplement like active (containing acidophilus and other beneficial bacteria) rather than pasteurized yogurt.

Dear Dr. Fox:

We have two 1-year-old cats. Their names are Ronnie and Nancy. They have been fixed and are inside cats. They are also very affectionate. My question is, why are their tails always wagging like a dog's? Can you tell me what that means?

K.G., King, N.C.

Cats wag their tails like dogs when they are excited. While tail wagging has evolved in dogs as a social greeting expressing friendly excitement, both dogs and cats lash their tails when agitated, and when displaying aggressive intentions. Cats display a vertical tail as a social greeting.

Tails are an important means of communication, and I have a dubious opinion about deliberately breeding dogs and cats to be tail-less, which can have harmful neurological consequences. And dogs should not have their tails docked because it is a "breed standard." Cats have scent glands in the skin of their tails, and when they slowly wag, curl and stroke their tails around your legs and furniture, they are actually marking with their scent. Other scent glands are located on the face, on the temples and chin, and around the lips.

(c) 2005, United Feature Syndicate Inc.