Pets and People: The Health Connection

Sigmund Freud, the founder of psychoanalysis, loved dogs, yet he never mentioned them in his research. Only recently have scientists begun to analyze the way we humans relate to other species.

Perhaps that's because we need to make sense of the close connections so many people have with their pets, from pythons to parrots, and from German shepherds to Vietnamese pot-bellied pigs.

Here are some of the most common questions people ask about their pets:

Is a dog's mouth cleaner than a human's?

Although many pet owners believe this, the answer is no. So why don't we get sick from Fido's kisses? Generally, it's because animals and humans carry different types of bacteria in their mouths. Dog and cat bacteria don't tend to affect humans. So a kiss from your cat can be safer than a kiss from your grandma.

But your cat's kiss won't be quite as safe as your dog's. There is a good chance that Spot's mouth is more sanitary, because a cat often cleans itself with its tongue.

Can you catch a cold from your pet?

Your runny-nosed cat licks you on the face and the next day you have the sniffles. Did you catch them from your pet? Not likely. You can catch some diseases, called " zoonoses," from your pet, but most pet viruses and upper respiratory infections aren't transmittable to humans. We carry different germs from those that inhabit our pets. For example, feline AIDS is a disease that attacks the immune system of cats in much the same way that human AIDS attacks the human immune system. But cats can't transmit feline AIDS to humans.

Though zoonoses are rare, you should be aware of one called toxoplasmosis. Cats can transmit this to people. The disease itself isn't dangerous for most healthy people; it consists of mild flu-like symptoms. But pregnant women who contract this disease may give birth to a baby with congenital defects. The expert advice: Pregnant women can have contact with cats, but they should let someone else clean out the litter box, where the greatest hazard lurks. Toxoplasmosis is also a danger to immunocompromised individuals, particularly those with AIDs. They may develop toxoplasmosis infections that destroy vision, and cerebral toxoplasmosis, which causes neurological disease.

Are pets good therapists?

Many studies have explored the relationship between pets and humans. One study found that pets can reduce the loneliness of residents in long-term care facilities, according to the Delta Society, a nonprofit group that organizes animal-assisted therapy for people with mental and physical disabilities, Pets cal also help lower blood pressure. People with borderline hypertension lowered their blood pressure on days when they took their dogs to work with them. Older adults who own dogs have fewer doctor visits than those who don't own dogs. Pet owners have lower triglycerides and cholesterol levels. Pet owners have better psychological well-being.

Can I have too many pets?

We usually hear about people with multiple pets from newspaper accounts: "Woman, 75, Found Dead With 50 Cats"; or "Health Department Raids Home of Hermit With 40 Dogs." The subjects of these stories have an unhealthy obsession with their pets. One study found that people who own too many pets suffer from a "rescue mentality," which seems to develop from a traumatic experience these individuals once suffered.

If someone owns multiple pets, however, it does not necessarily mean he or she has an unhealthy attachment to animals. Geraldine Rockefeller Dodge, for instance, had a kennel full of dogs, but she was wealthy and could provide them with good care. Some people, on the other hand, can't even cope with one cat.

Why are we more allergic to cats than dogs?

Proteins that animals release trigger allergic reactions in humans. These proteins may come from dried skin flecks, or from dander. Both cats and dogs produce these, but cats have an additional allergenic element, known as Fel d1. This is a protein found in cat saliva and skin flakes. When a cat licks itself, proteins in their saliva dry on their fur, then flake off into the air. Allergy-prone people may be particularly susceptible to these airborne proteins.