An estimated 38.2 percent of all U.S. households have a dog, 30.5 percent have one or more cats and 5.7 percent have a bird.

Yet, as popular as pets are, there are a number of myths about their lives and behavior that continue to surface, according to the American Animal Hospital Association, a trade group of veterinarians who treat "companion" animals. Here's a look at some of the most common myths:MYTH: Humans can get AIDS from cats.

FACT: Because of its similarities to human AIDS, feline immunodeficiency virus has been called "feline AIDS." This viral disease damages cats' immune systems, leaving the animals vulnerable to many serious infections and diseases.

However, the disease has never been passed to humans, even with veterinarians who have been exposed to the virus through open wounds or needle pricks.

MYTH: Bad breath is normal for all dogs.

FACT: Many times, mouth odor is a sign of dental disease. Food particles, tartar and bacteria collect in dogs' and cats' mouths, causing dental problems such as cavities and inflamed gums. This "halitosis" can be greatly reduced with regular brushing and veterinary dental checkups.

MYTH: Cats always land on their feet.

FACT: While cats instinctively fall feet-first and may survive falls from high-rise buildings, they may receive broken bones in the process.

MYTH: Animals that are spayed or neutered automatically gain weight.

FACT: Like people, pets gain weight from eating too much, exercising too little or both. In many cases, spaying or neutering is done at an age when the animal's metabolism already has slowed, and its need for food has decreased. If the pet continues to eat the same amount, it may gain weight. Pet owners can help their animals stay fit by providing exercise and by not overfeeding.

MYTH: Cats cannot get rabies.

FACT: Actually, most warm-blooded mammals, including cats, bats, skunks and ferrets, can carry rabies. Like dogs, cats and other mammals kept as pets should be vaccinated regularly according to local laws.

MYTH: Birds can carry rabies.

FACT: The normal body temperature is too high for rabies to survive. In contrast, the body temperature of snakes and other reptiles is too low for rabies.

MYTH: Indoor cats cannot get diseases.

FACT: In fact, cats still are exposed to organisms that are carried through the air or brought in on a pet owner's shoes or clothing. Even the most house-bound cat usually ventures outdoors at some time and can be exposed to diseases and worms through contact with other animals and feces.

MYTH: Tapeworms come from bad food.

FACT: Pets become infected with tapeworms from swallowing fleas that carry the parasite. Cats can get tapeworms from eating infected mice, and dogs can be exposed by catching infected rabbits or other rodents.

MYTH: Putting garlic on a pet's food will get rid or worms.

FACT: Garlic has no effect on worms. The only way to treat worms is by medication prescribed by a veterinarian.

MYTH: Cats should drink milk every day.

FACT: Most cats like milk, but do not need it if they are properly nourished. Also, many will get diarrhea if they drink too much milk. If it is given at all, the amounts should be small and infrequent.

MYTH: Pregnant women should not own cats.

FACT: Some cats are infected with a disease called toxoplasmosis, which occasionally can be spread to humans through cat litter boses and can cause serious problems in unborn babies. However, these problems can be prevented if the expectant mother avoids contact with the litter box and assigns daily cleaning to another family member.

MYTH: Bones are good for dogs.

FACT: Bones, especially small ones, actually can cause constipation, choking and laceration of the intestine. The only safe type is one that is too large to fit in the dog's mouth and too hard to splinter.

MYTH: A cat's sense of balance is in its whiskers.

FACT: Cats use their whiskers as "feelers," but not to maintain balance.

MYTH: A cold nose means a healthy dog.

FACT: In fact, dogs lick their noses frequently, and the evaporation of the moisture makes the skin cold. A dog can be sick with a fever and still have a cold, wet nose.

MYTH: Animals heal themselves by licking their wounds.

FACT: Such licking actually can slow the healing process and further damage the wound.