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Zoonotic Diseases & Dogs

Zoonotic Diseases & Dogs

A zoonotic disease is a disease that can be passed from animals to humans. These diseases can be caused by viruses, bacteria, parasites, and fungi. Humans can contract zoonotic or vector-borne diseases through contact with an animal, its bodily fluids, its infected waste or its living environment; by contact with water or soil contaminated by infected animal waste; by eating meat from infected animals or eating food such as fruits and vegetables that have been contaminated by infected animal waste; or through vectors—such from infected animals to humans via mosquitoes, fleas or ticks. Following are some zoonoses related to dogs:


Cryptosporidosis is an infection of the gastrointestinal system caused by the parasite Cryptosporidium parvum. Symptoms include watery diarrhea, fever, abdominal cramps, nausea, and vomiting. Many infected individuals require hospitalization and IV fluid therapy. Infection in immunosuppressed individuals such as the very young, the elderly or those with HIV/AIDS may be life threatening. Cryptosporidiosis has been found in people, cats and dogs living in the same environment, suggesting the potential for zoonotic transfer between species exists. Most people get cryptosporidosis from contaminated water, but be cautious with pet waste. If you develop these symptoms, contact your physician. Be sure to inform him or her of your pet and whether it is also ill. If your dog has diarrhea, take it to your veterinarian for an examination.


Caused by the parasite Giardia, giardiasis is the most frequent cause of nonbacterial diarrhea in North America and the most commonly diagnosed intestinal parasite in humans in Oregon, with 600 to 800 cases reported each year. It is transmitted most frequently through contaminated water. The most common sign of giardiasis in dogs is diarrhea, which can be acute, chronic, or intermittent. If your dog has diarrhea, take it to your veterinarian for an examination.


Leptospirosis is a bacterial disease spread through the urine of infected animals. In people, the symptoms are often flu-like. The risk of getting leptospirosis through common contact with a dog is low; the primary mode of transmission is through contact with contaminated animal urine. Symptoms in dogs include fever, vomiting, abdominal pain, diarrhea, refusal to eat, severe weakness and depression, renal disease, and liver dysfunction. Risk factors for dogs include contaminated water and contact with cattle, rats or raccoon urine. Leptospirosis can be treated with antibiotics. To help prevent leptospirosis, vaccinate your dog and keep rodents under control, and avoid contact with rodents and wildlife, including carcasses. Avoid letting your dog drink from marshy areas or slow-moving or stagnant water. A vaccine can protect your dogs against the most common bacteria causes of Leptospirosis.

Lyme Disease

Lyme disease is a bacterial disease that can cause a "bull's-eye" rash with fever, headache, and muscle or joint pain. In Oregon, a survey of deer ticks revealed that approximately 3-4% of those collected tested positive for the organism that causes Lyme disease. Ticks that carry Lyme disease primarily live west of the Cascades, in areas near Hood River, and west of Klamath County. If you are in an area where there are ticks, such as the woods, wear light-colored clothing so that ticks can be spotted more easily and removed before becoming attached, wear long-sleeved shirts, and tuck your pants into socks. Insect repellants containing DEET and permethrin can be effective. After hikes or other outdoor activities in high-risk areas, inspect yourself and your dog for ticks and remove them promptly, and be sure to treat your pet on an ongoing basis with a flea and tick prevention medication.

Methicillin-Resistant Staphylococcus Aureus (MRSA)

Transmission of MRSA infections between pets and humans are increasing, with the most common being infections of the skin, soft-tissue and surgical infections. Dog or cat bites can result in infection, caused by bacteria from the animal's mouth and on the patients' body. Animals are potential reservoirs of MSRA infection due to increasing prevalence of community-acquired MRSA (CA-MRSA) in humans and domestic animals such as dogs, cats and horses. MRSA-associated infections in pets are typically acquired from their owners and can potentially cycle between pets and their human acquaintances. Treatment of MRSA infections in pets is similar to that used in humans. Resistant to penicillin and methicillin, CA-MRSA infections can still be treated with other common-use antibiotics. CA-MRSA most often enters the body through a cut or scrape and appears in the form of a skin or soft tissue infection, such as a boil or abscess. The involved site is red, swollen, and painful and is often mistaken for a spider bite. Though rare, CA-MRSA can develop into more serious invasive infections, such as bloodstream infections or pneumonia, leading to a variety of other symptoms including shortness of breath, fever, chills, and death. CA-MRSA can be particularly dangerous in children because their immune systems are not fully developed. You should pay attention to minor skin problems—pimples, insect bites, cuts, and scrapes—especially in children. If the wound appears to be infected, see a healthcare provider.


Rabies is an infectious viral disease that affects the nervous system. It is only transmitted by a bite from a rabid animal. If you are bitten by any animal—even a household pet—and especially if the bite is from a wild animal, such as a bat, it is important to consult with your health care provider. 

Dogs, cats and ferrets should be vaccinated against rabies. Vaccinating pets not only protects them but it provides a “buffer zone” between humans and rabid wild animals. Oregon law requires all dogs to be vaccinated against rabies as early as three months of age. In addition, Multnomah County requires all cats to be vaccinated for rabies.

Oregon law requires that unvaccinated pets that may have been in contact with rabid animals to be vaccinated and quarantined for 4 months (dogs and cats) or 6 months (ferrets), or euthanized. The contact animal, such as a bat, is considered rabid unless it is tested and is negative.

Vaccinated dogs, cats, and ferrets exposed to a rabid animal should be revaccinated immediately, kept under the owner's control, and quarantined for 45 days. Any illness in an isolated or confined animal should be reported immediately to the local health department. If signs suggestive of rabies develop, the animal should be euthanized and tested.

There are an estimated 5 million dog bite incidents in the US per year. Of those, approximately 10,000 require hospitalization and about 20 people, mostly young children, die. Rabies vaccination and proper dog socialization can reduce these numbers. Dogs who are well-socialized and supervised are much less likely to bite.


Ringworm is not a worm, but a skin and scalp disease caused by fungus. Ringworm usually makes a bald patch of scaly skin or a ring-shaped rash that is reddish and may be itchy. The rash can be dry and scaly or wet and crusty. Ringworm is transmitted by direct contact with an infected animal's skin or hair. Dogs, especially puppies, can pass ringworm to people, so preventative care by your veterinarian is important.


Salmonellosis is caused by the bacteria Salmonella. It can cause diarrhea, fever and abdominal cramps 12 to 72 hours after infection. The illness usually lasts four to seven days, and most people recover without treatment, although it can be fatal to those with fragile immune systems. About 40,000 human cases of Salmonella infection are reported in the US each year. Dogs with Salmonella infections may be lethargic and have diarrhea or bloody diarrhea, fever, and vomiting. Some pets will have only decreased appetite, fever and abdominal pain. Well animals can be carriers and infect other animals or humans. It is possible to contract Samonella from handling contaminated pet food or treats.

Dog owners should wash their hands after touching dogs who are sick and/or handling their waste. If you have a cat, scoop the litter box daily and dispose of the stool in a tightly sealed plastic bag. If you have a dog, clean up its waste while on walks or from the yard and dispose of the stool in a tightly sealed plastic bag.  

To reduce infection risks, you should:

  • Wash hands after contact with pets, pet food and pet bowls. Wash with soap and running water for at least 20 seconds, then rinse and dry your hands with a paper towel.
  • Routinely clean pet food bowls, feeding areas, litter boxes and habitats.
  • Keep children younger than age 5 away from pet food and feeding areas.
  • Clean pets' food and water dishes in a separate sink or tub, not in the kitchen or bathtub.
  • Avoiding bathing infants in the kitchen sink.

Unfortunately, pet food can be contaminated by Salmonella, and recalls of pet food have occurred. Please check our Recalls & Warnings section for the latest information on current recalls.

Toxocariasis (Roundworm)

Adult roundworms are an intestinal parasite that resemble strands of spaghetti. Their eggs are shed through a pet’s feces and, while fresh feces are not infectious, the eggs become infectious over time as they sit in grass, soil or sand. This is why picking up pet waste promptly is important. Roundworms can cause vomiting or diarrhea. Children are more prone to contract roundworm as they are more likely to touch infected dirt or sand and then put their hands into their mouths. Do not let children eat sand or dirt. Children should wash hands thoroughly after playing in areas where pet waste may have been deposited. Keep sandboxes covered when not in use. In rare cases, roundworm infection can cause an eye disease that can lead to blindness; such infections can be more serious in children than adults. Gardeners should wear gloves and wash hands after working outside.


  • Regular veterinary care is important for the health of every animal. Because any dog at any age can become infected with parasites, an annual exam with a fecal exam is important. Your veterinarian can recommend a parasite prevention and vaccination protocol for your dog to keep it safe from infectious diseases.
  • One of the best ways to prevent zoonotic diseases is to promptly clean up pet waste. Many parasites or bacteria are not infectious in fresh pet waste, but become infectious over time and can contaminate the soil, sand or grass if allowed to sit.  Wash your hands thoroughly with hot, soapy water after playing with your dog or handling its waste.
  • If you have any questions about these diseases or concerns about your pet's health, please consult your veterinarian. If you have concerns about your health, please seek medical attention from your health care provider.

Updated: June 25, 2019