Zoonotic Diseases in Dogs

What is a zoonotic disease?

Zoonotic disease or zoonoses are terms used to describe an infection or disease that can be transmitted from an animal to a human being.

Are there many zoonoses?

Altogether, well over one hundred diseases are capable of being transmitted from animals to humans, although most are rare in North America. All domestic animals including dogs, cats, birds, horses, cows, sheep, goats, and rabbits can potentially spread diseases to people, but rarely does this actually occur. If pet owners exercise basic hygiene principles, especially hand washing, most of these potential diseases can be avoided.

How great is the risk of contracting a zoonotic disease from my dog?

Current evidence supports the fact that pet dogs pose a minimal zoonotic risk to their human companions. Risk may be slightly higher in people with a compromised immune system from disease or medication, such as:

• people with AIDS/HIV.
• people on chemotherapy or receiving radiation therapy.
• people who are elderly or have chronic diseases.
• people with congenital immune deficiencies.
• people who have received organ or bone marrow transplants.
• pregnant women (the fetal immune system is not fully developed, and the pregnant woman's immune system is altered during pregnancy).

If you fall into one of these categories, it does not mean you have to give up your pet. It simply means that you should take some basic precautions such monitoring your dog for any signs of illness, washing your hands after extensive handling of your dog, and avoiding direct contact with your dog's feces or urine.

It is important to keep in mind that numerous studies prove that the benefits of having a pet far outweigh the risks. Sharing your home with a pet is often just what the doctor ordered.

What are the most common zoonotic diseases of dogs?

• ringworm
• salmonellosis
• leptospirosis
• Lyme disease
• campylobacter infection
• Giardia infection
• cryptosporidium infection
• roundworms
• hookworms
• tapeworms
• scabies
• harvest mites
• rabies

What zoonotic diseases are the most likely to cause serious illness in people?

Rabies, caused by a virus, is almost invariably fatal in humans.

Certain infectious organisms, such as the bacteria Salmonella and Campylobacter and the protozoan disease caused by Giardia, can cause severe gastroenteritis.

Leptospirosis, known as Weil's disease in people, can cause extremely serious liver and kidney disease but the transmission from dogs to humans is rare. Humans usually contract this disease from exposure to contaminated water.

Roundworms (Toxocara canis) and tapeworms (Echinococcus species) can cause liver problems, but illness in people from these causes is rare. Direct handling of infected dog feces can potentially cause an infection of roundworms in a susceptible person. Echinococcus tapeworm infections are starting to become more common in areas of Canada and the United States where they had not been recognized before (see handout "Echinococcosis in Dogs" for more information on this disease). Transmission to humans can result from ingestion of eggs released in an infected dog’s feces.

Zoonotic skin diseases including ringworm, caused by the fungus Microsporum canis and scabies, caused by the mite Sarcoptes scabiei, Cheyletiella mites, and harvest mites (Trombicula species) are transmitted relatively easily to people through direct physical contact.

How can I reduce the risk of contracting one of these diseases from my dog?

Simple hygiene and common sense will drastically reduce, if not eliminate, the risk of zoonotic spread of disease from dog to people. Some of the things you can do include:

• Make sure that any sign of illness or disease in your dog is diagnosed and treated promptly by your veterinarian. If your dog is sick, make sure you wash your hands after all contact with him.
• Bathe and groom your dog. This will increase the chance of early detection of any skin lesions.
• Give your dog a broad-spectrum deworming product on a regular basis. The simplest way to do this is to use a monthly heartworm product that includes a dewormer.
• Wear gloves when gardening or working in areas where dogs, cats, or other animals may have urinated or defecated.
• Pick up any feces on your property and stoop and scoop when you take your dog for a walk. Dispose of all waste materials promptly and safely.
• Do not allow your children to contact your pet's feces OR your pet to contact your chidren's feces. 
• Always ensure you wash your hands after handling any animal.
• Provide separate food and water dishes for your dog, and wash and store them separately from your family's dishes.
• Wash pet bedding frequently.
• Use flea and tick control products on a routine basis.

Following these simple precautions ensures you have done everything to reduce any risk to you and your family.

Can I transmit disease to my dog?

Transmission of disease can occur from people to dogs. Sore throats, tuberculosis, and fleas are common examples. Additionally, enteritis due to Campylobacter and Salmonella infections can be passed from an infected family member to the family dog.