Psychology pioneer Sigmund Freud loved dogs, yet he never mentioned them in his research. It's only in recent years that scientists have 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, German shepherds to Vietnamese pot-bellied pigs.
Here are some of the most common questions people ask about their pets:
Although this is a widely held belief among pet owners, 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 the cat's kiss won't be quite as safe as a dog's. There is a good chance that Spot's mouth is more sanitary, because a cat often cleans itself with its tongue.
Your runny-nosed cat licks you on the face and the next day you have the sniffles. Did you get it from your pet? Not likely. There are some diseases you can catch from your pet, called "zoonoses," but most 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, there's at least one you should be aware of. It's called toxoplasmosis, and it can be transmitted from cats 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 who may develop toxoplasmosis infections that destroy vision and cerebral toxoplasmosis that causes neurological disease.
Many studies have explored the relationship between pets and humans. Among the results, as cited by the Delta Society, a nonprofit group that organizes animal-assisted therapy for people with mental and physical disabilities: Pets can reduce the loneliness of residents in long-term care facilities. 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.
Not unless you live close to where you left him. Remember "Homeward Bound," the Disney movie about two dogs and a cat that manage to find their way home from thousands of miles away? It makes quite an impression on pet owners, many of whom believe their animals have a great innate tracking ability.
But the idea that animals can track their way across the country to find their owners is a folk tale, experts say. In fact, pets rely on their sense of smell, rather than sight, to guide them back to familiar turf. Because smells change, an animal is actually more likely to get lost than humans.
This doesn't mean pets are completely clueless about their home territory: Most have a specific distance they can travel from home and still find their way back -- about a mile for city pets, and farther for country pets.
We usually find out about multiple pet owners 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" that seems to come out of a traumatic experience they themselves once suffered.
It isn't just the number of pets that determines whether a person has an unhealthy attachment to animals. Geraldine Rockefeller Dodge, for instance, had a kennel full of dogs, but she was wealthy, so she could find a place for them. But some people find they can't even cope with one cat appropriately.
Allergic reactions are set off by proteins released by animals. These proteins can be from dried skin flecks or from dander. Both cats and dogs produce these, but cats have an additional allergenic element. As a cat licks itself, proteins in saliva dry on the fur, then flake off into the air. Allergy-prone people may be particularly susceptible to these airborne proteins.
© 2013 Main Line Health