About Capnocytophaga

Key points

  • Capnocytophaga bacteria can cause a rare but potentially serious infection.
  • People usually get infected if they're bitten by a dog or cat.
  • People with weakened immune systems are at higher risk for infection and serious illness.
  • People bitten by a dog or cat should call a healthcare provider immediately.
images of dogs and cats


Many kinds of bacteria (germs) are found in the mouths of dogs and cats. One common group of bacteria are called Capnocytophaga. These germs sometimes cause opportunistic infections, which means under the right conditions they can cause an infection, such as in a person with a weakened immune system.

image of a dog licking his owners face
Capnocytophaga bacteria are commonly found in the mouths of dogs and cats.

Capnocytophaga germs can make people sick if they're bitten or the dog or cat's saliva (spit) gets into an open wound or sore.

Most people who have contact with a dog or cat do not become sick. People with weakened immune systems who have difficulty fighting off infections are at greater risk of becoming sick if they're bitten.

Don't Get Bitten‎

Read more about how to prevent animal bites and what to do if you are bitten, regardless of your health status.

Capnocytophaga infection can cause serious complications, including sepsis, heart attack, kidney failure, and gangrene. Some people may need to have fingers, toes, or limbs amputated.

If you have been bitten by a dog or cat, wash the bite area right away with soap and water. Call your doctor or go to an urgent care clinic. Even if you don't feel sick, dog and cat bites can cause a Capnocytophaga infection and other diseases like Pasteurella, Bartonella (cat-scratch disease), or rabies.

Other types of Capnocytophaga infection

Other Capnocytophaga germs can also be found in human mouths and cause the people who have them to get sick. People who have weakened immune systems get this type of infection more often than healthy people.

People who get sick from the kinds of Capnocytophaga found in people’s mouths can get infections in their eyes, gums and mouth tissues, and respiratory tracts (nose, throat, lungs).

Capnocytophaga infection from dog or cat bites are much more common than illness from human mouths.

Signs and symptoms

If you have the following symptoms within 14 days of being bitten by a dog or cat, contact a healthcare provider immediately and tell them that you were recently bitten by an animal.

People who are infected with Capnocytophaga can have a range of signs and symptoms:

  • Blisters around the bite area
  • Redness, swelling, draining pus, or pain at the bite area
  • Fever
  • Diarrhea and/or stomach pain
  • Vomiting
  • Headache and/or confusion
  • Muscle or joint pain

In all Capnocytophaga infections the bacteria can enter the blood stream, which can lead to infection in various parts of the body (sepsis). Infection can also cause the following:

  • Inflammation of the lining of the heart (endocarditis)
  • Collections of pus, redness, and swelling in various body tissues (abscesses)
  • Inflammation of the eyes, face, lymph nodes, or brain membranes (meningitis)

Who's at risk

Most dog or cat bites do not lead to a Capnocytophaga infection or any illness. But you should take precautions if you have contact with animals, especially if you have a condition that puts you at higher risk of infection. These conditions include:

  • People with alcohol disoders
  • Not having a spleen (asplenic)
  • Having a weakened immune system (immunocompromise) from conditions like cancer, diabetes, or HIV, among others
  • Taking certain medicines that weaken your immune system, such as chemotherapy

If any of these conditions apply to you, speak with your healthcare providers about how to be safe around dogs and cats.


Preventing Capnocytophaga infection starts with preventing bites and scratches from dogs and cats, especially if you have a condition that puts you at higher risk of getting sick.


There are many benefits to having pets like dogs and cats. CDC's Healthy Pets Healthy People has safety tips for safer contact with pets.


Call your healthcare provider immediately after being bitten by a dog or cat. They may want to start you on antibiotics if you have an increased risk of infection.

If you test positive for Capnocytophaga germs, you will need to start treatment as soon as possible to help prevent serious complications.

A Capnocytophaga infection can be treated with different kinds of antibiotics prescribed by a health care provider. You may need to take more than one antibiotic to help you get better.