Dr. Margaret J. White, DVM

Dogs and cats are invaluable members of the family; however in some cases they can transmit disease. A zoonotic disease is a disease transmitted directly or indirectly from animals to people. People most at risk of developing a zoonotic disease are children under 5, the elderly, pregnant women, and people who have poor immune systems due to chemotherapy or chronic disease. The risk of developing a zoonotic disease can be drastically reduced by providing good preventative medical care to your pets. Keeping your pet on year-round monthly flea and tick preventatives, on monthly heartworm/intestinal worms preventatives, and properly vaccinated can keep the human members of your family healthy too.

Vaccines can protect your family against diseases such as Leptospirosis and Rabies. Dogs and other animals can transmit Leptospirosis to people through infected urine, and you can prevent your dog against contracting Leptospirosis by keeping him currently vaccinated. Leptospirosis in people can cause a high fever, severe headache, vomiting and eventually liver and kidney disease if left untreated.  Rabies is a well known viral zoonotic disease capable of being transmitted by all mammals to people thru bite wounds and contact with infected saliva. Rabies is nearly 100% fatal in humans if medical care is not received. In the United States, most recent human cases of Rabies involve exposure to bats. Other wildlife such as skunks, raccoons, and foxes also commonly transmit Rabies. Cats are a higher Rabies risk than dogs in this country since they are more likely to be outside hunting and less likely to be vaccinated against Rabies. In other parts of the world, stray dog’s bites are the primary source of Rabies transmission.  All states require dogs and cats over 3 months of age to be up-to-date on Rabies vaccines to protect public health.

Most of us have been taught as children to avoid touching dog or cat stool.  This is sage advice since multiple zoonotic diseases are transmitted by contact with stool. Toxoplasmosis can be spread by contact with cat stool or soil contaminated by cat stool, but most cases are acquired from eating contaminated meat.  Cats are only capable of transmitting the Toxoplasmosis parasite to humans for 10-14 days after exposure, and therefore human exposure to pet cats is a small risk. 50% of people have actually been exposed to Toxoplasmosis, but only women initially exposed during the first trimester of pregnancy are at a health risk.  Toxoplasmosis can cause miscarriage and birth defects.  The likelihood of transmission of Roundworms  from pets is moderate to high. Roundworms of cats and dogs are transmitted through the stool and can rarely cause blindness, respiratory disease, and liver disease. Hookworms are another intestinal parasite of dogs that can contaminate soil and beaches. The larvae can penetrate human skin and migrate thru the body causing intolerable itching. Keeping your pets on year-round heartworm with intestinal parasite protection,  as well as testing your pets stool for intestinal parasites twice yearly can protect you family from roundworms and hookworms.

Some zoonotic diseases can be transmitted to your family by close contact with an infected pet’s fur and skin. Ringworm is a fungal infection that causes bald patches, scaly areas, and itching in people and pets. Cats that live in multi-cat households or outside  can have the fungus on their fur and not necessarily have evidence of skin disease. Thus, people can contract Ringworm from what appears to be an apparently healthy cat. Scabies is a mite that burrows under the skin of both dogs and cats and causes severe itching and bald, red areas. Scabies can crawl from infected cats and dogs and burrow into the skin of people. Some flea and tick preventatives also protect cats and dogs from Scabies.  Cat Scratch Fever, also known as Bartonella, can be transmitted to a person by a cat bite or scratch. Cats acquire Bartonella bacteria from infected fleas and ticks, and then infected flea feces enter a human wound from a bite or scratch.  Irritation at the site of the wound , swollen lymph nodes, fever, headache, and fatigue can develop in the infected person.

After discussing the potential health risks to your family from pet ownership, it is important to note the many health benefits from pet ownership. Pet ownership encourages regular exercise, provides  companionship, and can help teach children responsibility.  Studies have shown that pet ownership is linked to reduced incidence of allergies in young children, decreased depression among the elderly, and a decreased risk of hypertension. In general, the human members of the family are more at risk from contracting infectious diseases and parasites from each other than their pets.

Guidelines to protect your family and your pets:
1.    Have your veterinarian test your cat’s and dog’s stool twice yearly for intestinal parasites
2.    Keep all cats and dogs on year-round, monthly heartworm and intestinal parasite preventatives
3.    Cover sandboxes to prevent stool contamination from outside cats
4.    Pick up dog and cat stool regularly especially in yards where children play
5.    Wash your hands after contact with soil, stool, or pets
6.    Check daily for ticks on your family and pets
7.    Pregnant women should wear gloves if they have to clean the cat’s litter box
8.    Clean scratches and bites from cats and dogs immediately
9.    Vaccinate your dog against Leptospirosis and all cats, dogs and ferrets against Rabies
10.    Keep all cats and dogs on year-round, monthly flea and tick preventatives.

Dr. Margaret J. White, DVM is currently Chief of Staff at Centreville Veterinary Hospital in Wilmington, DE. She has 13 years experience in small animal medicine and surgery, and works with dogs, cats, ferrets, rabbits, guinea pigs and other small mammals. Dr. White graduated with a Doctor of Veterinary Medicine degree from the Virginia-Maryland Regional College of Veterinary Medicine at Virginia Tech in 1997 and with a Bachelor of Arts in Biology from the Catholic University of America in 1992.