While we think of our canine companions as sharing our lives, possibly even our beds, we need to remember that they might just share some health problems as well. This is no reason to banish your dog from the house; instead, it's a way to stress the importance of good care to keep both you and your dog healthy. Illnesses that people share with animals are called zoonoses, and they range from parasites to bacteria and viruses. Remember, too, that many of these diseases can be passed back and forth both ways.

Common Zoonoses

Some of the most common zoonoses are parasites (as described in Chapter 12). These can be external parasites, such as fleas, or internal parasites, such as roundworms. Both you and your dog can be innocent hosts for fleas and ticks. While the fleas might prefer your nice furry dog, they will enjoy a human blood meal if it is available. Clearly, keeping your dog parasite-free is in your best interest as well.

Roundworms are the intestinal parasite most often seen in puppies. Good hygiene can prevent the spread of this parasite to people, along with the potential serious complications it can cause, such as blindness. Again, cleanliness and keeping your dog healthy by preventive medications and doing regular fecal checks will be beneficial to the whole family.

A few bacterial diseases can be shared too. If children keep getting strep throat, their pediatrician may recommend a throat culture of your dog. Sometimes children and dogs (or cats) will share strep bacteria back and forth, so just when you get your child cured, she picks it up again from the dog. Putting everyone on a course of antibiotics together may end this cycle of zoonotic disease.

The More Exotic Zoonoses

Some of the most serious zoonotic diseases are generally quite uncommon. Rabies is high on the list here. Rabies is almost universally fatal, and a dog with rabies could easily bite a family member and spread the disease. Due to the serious nature of this disease, rabies vaccination is required by law in most areas.

The tapeworms that cause hydatid cysts and life-threatening liver disease in people are not very common, but herding dogs imported from endemic areas do need screening.

None of these examples is meant to scare you. You are much more likely to share disease organisms with a friend or coworker than with your dog.