Is Your Cat’s Mouth a Bacterial War Zone? The Truth About Feline Saliva


Cats’ mouths contain bacteria that are harmless to cats but can cause infections if transmitted to humans. While the risk of disease transmission is low for healthy humans, cat bites and scratches can lead to various illnesses. This article provides an overview of the potentially harmful bacteria found in cat saliva, how they can be transmitted to humans, the associated health risks, precautions cat owners should take, treatment options, and when to see a doctor.

We will examine which bacteria are commonly present in cats’ mouths, which of these pose a potential risk to humans, and the diseases they can cause if transmitted through a bite or scratch. The article also covers ways cat owners can reduce the risk of transmission, as well as what to do if scratched or bitten. Treatment options, preventative veterinary care, and guidance on when to seek medical attention are also provided.

Bacteria Naturally Present in Cat Saliva

Cat saliva contains a diverse microbiome with a wide variety of bacteria that enter the mouth from the food cats eat and the environments they explore. According to the Cornell Feline Health Center, over 100 different bacterial strains have been identified in cat saliva so far (1). Many of these bacteria are harmless normal flora found in the mouths of healthy cats. Cats tend to have higher levels of bacteria like Pasteurella, Streptococcus, Bartonella, and Neisseria species compared to dogs and people.

Potentially Harmful Bacteria

Cat saliva can contain potentially harmful bacteria that are capable of causing illness in humans. Three major bacteria of concern are:

  • Pasteurella multocida – This bacteria naturally lives in the mouths and throats of many animals, including cats and dogs. In humans, it can cause skin infections, respiratory infections, and sepsis if it enters deeper tissues or the bloodstream, especially in immunocompromised people.[1]
  • Capnocytophaga – Multiple species of this bacteria genus are commonly found in cat and dog saliva. For healthy people, infections are rare. But bites or scratches can lead to dangerous infections in infants, elderly, or immunocompromised individuals. Symptoms include fever, vomiting, diarrhea, and muscle/joint pain.[2]
  • Bartonella henselae – Also called cat scratch disease (CSD), this bacteria can be transmitted via infected fleas or cat scratches/bites. It often leads to swollen lymph nodes and fever in humans. CSD is generally mild in healthy people but can be severe for those with weakened immune systems.[3]

While healthy individuals may not become sick from these bacteria, immunocompromised people are at much higher risk of developing potentially serious illnesses. All cat owners should be aware of the harmful bacteria potentially present in cat saliva.


Transmission to Humans

Cats have bacteria naturally present in their saliva and mouths that can potentially cause illness in humans if transmitted through a bite or scratch. The main bacteria of concern are Bartonella henselae, which causes cat scratch disease, and Capnocytophaga species.

Cat scratch disease is transmitted when a person is bitten or scratched by a cat infected with B. henselae. The bacteria enters the skin through the wound and multiplies, causing swollen lymph nodes near the injury site. Symptoms usually appear 3-10 days after exposure and include fever, headache, fatigue, and loss of appetite (Cornell Feline Health Center).

Capnocytophaga bacteria can be transmitted through bites, scratches, or close contact with cats and dogs. In rare cases it causes severe illness in humans, including blood infections, sepsis, and gangrene. People with weakened immune systems are at highest risk (CDC).

To prevent transmission, proper handwashing after interacting with pets is recommended. Bite wounds should be thoroughly cleaned and monitored for signs of infection. Prompt medical care is essential if any concerning symptoms develop after a cat bite or scratch.

Disease Risks

Cat saliva can contain bacteria that pose disease risks to humans. Some of the most concerning illnesses that can be transmitted from cats to humans include:

Cat Scratch Fever – Also known as cat scratch disease (CSD), this illness is caused by the bacterium Bartonella henselae. It is carried in infected cat saliva and fleas. Cat scratch fever occurs when saliva from a bite or scratch enters the wound. Symptoms include swollen lymph nodes, fever, fatigue, and loss of appetite. While usually self-limiting, it can cause more serious complications in some cases. [1]

Infections – Bacteria like Pasteurella, Capnocytophaga, and Staphylococcus can be transmitted through cat saliva. This can lead to wound infections, blood infections (sepsis), and other problems if the bacteria enter the body through a bite or scratch. Immunocompromised individuals are at higher risk. Proper wound care is important.

Rabies – Though rare, cats can transmit the rabies virus via bites and scratches. Once symptoms appear, rabies is almost always fatal. However, the rabies vaccine provides effective prevention. Keeping cats up to date on rabies shots is critical.

Precautions for Cat Owners

While a cat’s saliva contains bacteria, there are some precautions cat owners can take to reduce the risk of infection:

Wash your hands with soap and water after petting, holding, or having other contact with cats, especially before eating or touching your face. Scrub your hands thoroughly for at least 20 seconds.[1] Handwashing helps remove any bacteria that may have been transferred from a cat’s saliva onto your skin.

Take care if you get bitten or scratched. Wash bites and scratches right away with soap and warm water. Contact your doctor if the wound becomes red, swollen, warm, or tender, as antibiotics may be needed.[2] Seek prompt medical attention for any bites or scratches on your face, since these can be more prone to infection.

Avoid touching your eyes, nose, or mouth after petting a cat until after you’ve washed your hands. This prevents accidentally transferring bacteria into areas where it could more readily cause infection.

Have your veterinarian screen your cat for potentially harmful bacteria and parasites through routine wellness exams and laboratory tests. Treating any infections your vet finds will lower your cat’s bacteria levels.[3]


If a person develops an infection from a cat bite or scratch, antibiotics may be prescribed. Antibiotics commonly used to treat infections caused by cat saliva bacteria include azithromycin, ciprofloxacin, clarithromycin, and trimethoprim-sulfamethoxazole 1.

Wound care is also an important part of treatment. The bite or scratch should be thoroughly cleaned with soap and water to help prevent infection. Keeping the wound covered until fully healed can also help prevent bacteria from entering 2.

If a bite is severe, a tetanus shot may be recommended if the person’s tetanus vaccination is not up to date. Tetanus lives in the saliva of cats and deep puncture wounds can provide an environment for the bacteria to grow 3.

Routine Veterinary Care

Regular veterinary care is crucial for keeping cats healthy and reducing bacteria in their mouths. Annual exams allow vets to thoroughly inspect the teeth, gums, and oral cavity for signs of infection or disease. Early detection and treatment can prevent minor issues from developing into more serious conditions.

Vets recommend a full dental cleaning and polishing every 6-12 months to remove tartar and plaque before they irritate the gums. Cats prone to gingivitis or stomatitis may require more frequent teeth cleanings. Daily tooth brushing at home is another effective way to disrupt bacteria-harboring plaque.

Wellness checks also include updating vaccines that protect against viral infections affecting the mouth like feline calicivirus. Staying current on vaccines reduces the likelihood of contracting contagious illnesses leading to oral inflammation, ulcers, and excess bacteria.

Following a vet’s preventative recommendations helps minimize harmful bacteria and oral disease. Addressing problems early on improves comfort and avoids the need for tooth extractions down the road.

When to See a Doctor

Cat scratches and bites can cause bacterial infections like cat scratch disease. If you experience any signs of infection after being scratched or bitten by a cat, it is important to seek medical care. Signs of infection include:

  • Redness, swelling, warmth, or tenderness around the scratch or bite
  • Pus or oozing from the wound
  • Enlarged lymph nodes near the site of the scratch or bite
  • Fever or chills
  • Headache, fatigue, loss of appetite
  • Joint pain or body aches
  • A red streak extending from the wound

See your doctor right away if you experience any of these symptoms, as prompt antibiotic treatment can help prevent the infection from becoming more serious. Let your doctor know if the scratch or bite was from a cat so they can test specifically for cat scratch disease if needed. With appropriate care, most cat scratch infections can be treated effectively.


Cat saliva contains bacteria, some of which are harmless and some that can potentially cause illness in people. While the natural bacteria in a cat’s mouth are rarely an issue, bites and scratches can allow more harmful bacteria to be transmitted. Diseases like cat scratch fever or infections can develop from a cat bite. To reduce risks, cat owners should practice good hygiene, properly clean wounds, and keep cats up to date on vaccines and veterinary visits. Most of the time, cat saliva is not a major health concern. But people with weakened immune systems and owners of cats with dental disease or bite histories may need to exercise more caution. Overall, the bacteria in cat saliva is not cause for alarm, but staying informed on risks allows cat owners to take proper precautions.

Scroll to Top