The Hidden Toxin in Your Cat’s Saliva

Can a Cat’s Kiss Kill You?

Cat owners are extremely familiar with the feeling of their cat’s scratchy tongue giving them an affectionate lick or lap. Most see it as a quirky sign of their feline’s fondness. However, some may wonder if their cat’s slobbery kisses could be dangerous. There is an enduring myth that a cat’s saliva contains toxins that are harmful to humans.

Cat saliva does contain bacteria that can cause illness in people. But is it really toxic enough to kill you? Let’s examine the facts behind this urban legend.

What is the Toxin in Cat Saliva?

The toxin found in cat saliva is a bacteria called Pasteurella multocida. Pasteurella is a common commensal organism that lives in the oral cavity and upper respiratory tract of many animals, including an estimated 70-90% of healthy cats (Cornell Feline Health Center).

As an opportunistic pathogen, Pasteurella usually does not cause any issues in cats, but can be transmitted through bites and scratches and lead to infection in humans and other animals. Pasteurella is a zoonotic bacterium, meaning it can be transmitted between animals and humans.

Once transmitted, Pasteurella releases toxins that allow it to spread in the body, leading to localized wound infections or more serious systemic illness if it enters the bloodstream. Pasteurella can infect bones, joints, the respiratory system, and other areas in susceptible individuals.

How Common is Pasteurella in Cats?

Pasteurella multocida is a bacterium commonly found in the upper respiratory tract of cats. Studies show that 70-90% of healthy cats carry Pasteurella, either in the oral cavity, nasal passages, or throat. The carriage rate is high in both pet cats and free-roaming strays.

One study examining oral bacteria in 107 cats found Pasteurella in 88% of the cats sampled. Another study detected Pasteurella in the nasal passages of 91% of shelter cats tested. So while exact prevalence varies between studies, research consistently shows that the majority of cats harbor these bacteria as part of their normal flora.

Cats can carry Pasteurella without any signs of illness. But the bacteria can pose a risk when transmitted by bites or scratches. Understanding the prevalence in cats helps assess the transmission risk to humans interacting with cats.

How is Pasteurella Transmitted?

Pasteurella is most commonly transmitted to other animals and humans through bites and scratches from a cat (Source). The bacteria live in a cat’s mouth and respiratory tract. When a cat bites or scratches hard enough to break skin, their saliva can enter the wound and transmit pasteurella. Even playful nips can be enough to transmit the bacteria if they break the skin.

Pasteurella can also be transmitted through licks on open wounds or mucous membranes, though this is less common. Additionally, pasteurella can spread between cats via sneezing and coughing. Overall, cat bites and scratches are the primary route of pasteurella transmission to humans and other animals (Source).

What Are the Effects on Humans?

Pasteurella multocida bacteria can cause various symptoms and health issues in humans. The most common symptoms from Pasteurella infection are:

  • Skin infections at the bite or scratch site, including swelling, redness, pain, and pus (1, 2). These are the most frequent effects.
  • Respiratory issues like sinusitis, pharyngitis, and pneumonia, especially in people with chronic lung disease (1, 3).
  • Joint pain or septic arthritis if the bacteria spreads to the joints (1).
  • Rarer issues like meningitis, endocarditis, and eye infections (1, 2).

In general, people with weaker immune systems, such as the elderly, may develop more severe Pasteurella infections that require antibiotic treatment. Otherwise healthy individuals typically experience milder skin symptoms that resolve on their own (2, 3).

At-Risk Groups

Certain groups of people are at higher risk for developing serious illness from diseases transmitted through cat saliva. According to the CDC, the elderly, pregnant women, and immunocompromised individuals are most susceptible to potentially dangerous infections from pets, including cats [1].

The elderly tend to have weaker immune systems and underlying health conditions that make it harder to fight off infections. Pregnant women are also immunocompromised to some extent and infections can potentially pose a risk to the developing fetus. People with immunocompromising conditions like HIV/AIDS, organ transplant recipients taking immunosuppressant medications, and those undergoing cancer treatment are much more vulnerable to any pathogens transmitted by cats.

For these higher risk groups, extra care should be taken to avoid direct contact with cat saliva through licks or bites. Prompt medical attention is crucial if an infection does occur. While the risk is relatively low for healthy individuals, immunocompromised people may develop severe complications from diseases carried in cat saliva and shed by cats asymptomatically, like Capnocytophaga and Bartonella.

Reducing Transmission Risk

There are several steps that cat owners can take to reduce the risk of contracting an infection from Pasteurella in cats:

Play gently with cats using toys instead of hands and feet. Avoid rough play or interactions that may lead to bites and scratches. Supervise children when playing with cats.

Consider declawing your cat if they exhibit aggressive scratching behavior. While controversial, declawing can prevent scratches that expose Pasteurella bacteria.

Always wash hands thoroughly with soap and warm water after petting, holding, or playing with a cat. Clean any bites or scratches immediately with soap and water. Keep wounds covered until fully healed.

Avoid nuzzling faces with cats and actions where a cat may easily lick near the mouth or nose. Do not let cats lick open wounds.

Routinely clean food bowls, bedding material, and litter boxes to prevent spread of bacteria. Disinfect surfaces a cat may have scratched, sneezed on, or licked.

Monitor cats for dental disease, abscesses, or respiratory illness which may increase shedding of Pasteurella bacteria.

Speak with your veterinarian about testing cats to determine if they carry Pasteurella bacteria. Have cats checked and treated regularly for conditions associated with Pasteurella shedding.

Isolate cats exhibiting aggressive behavior or those known to carry Pasteurella from infants, elderly individuals, or immunocompromised people.

While not completely preventable, these precautions can significantly lower the chances of Pasteurella transmission from cats.

Treating Pasteurella Infections

Pasteurella infections are treated with antibiotics. The antibiotic of choice is amoxicillin-clavulanate, which covers both Pasteurella multocida and anaerobic bacteria from the oral flora. Amoxicillin-clavulanate can be given orally for uncomplicated skin infections. The typical dosage is 875/125 mg twice daily for 7-10 days in adults or 20-40mg/kg/day of the amoxicillin component given in divided doses every 12 hours for children (https://www.ncbi.nlm.nih.gov/books/NBK557629/).

For more serious infections like infected animal bite wounds, IV antibiotic therapy is recommended initially. Typical IV antibiotics include ampicillin-sulbactam, ticarcillin-clavulanate, piperacillin-tazobactam, or a carbapenem. After clinical improvement, patients can transition to oral amoxicillin-clavulanate to complete a 7-14 day course (https://emedicine.medscape.com/article/224920-medication).

Other oral antibiotics that can be used to treat uncomplicated Pasteurella skin infections include tetracyclines, fluoroquinolones, second and third generation cephalosporins, and clindamycin. However, amoxicillin-clavulanate is preferred as first-line therapy (https://www.uptodate.com/contents/pasteurella-infections).

Should You Avoid Cats?

While pasteurella infections can be concerning, there is no need for most people to avoid cats. The vast majority of pasteurella infections from cat bites and scratches are relatively mild and easily treated with antibiotics. Serious infections are quite rare in healthy individuals.

That said, people with compromised immune systems, chronic respiratory conditions, or other high-risk factors should take some basic precautions when interacting with cats:

  • Avoid rough play or activities that may lead to bites or scratches.
  • Wash hands thoroughly after petting or handling cats.
  • Have any bites, scratches, or wounds cleaned and monitored closely.
  • Consider antibiotic prophylaxis if bitten or scratched.

While it’s unlikely for pasteurella to cause major illness in most cat owners, at-risk individuals should consult their doctor about precautions to reduce infection risk. But for healthy people, the benefits of cat companionship far outweigh the modest risks.

Conclusion

In summary, cats do carry a toxin called Pasteurella in their saliva that can cause infection if transmitted to humans through bites or scratches. However, Pasteurella infections are generally not severe and can be treated with antibiotics. The bacteria is present in over 50% of healthy cats, so avoiding cats entirely is not necessary. Those at highest risk are the elderly, pregnant women, and those with weakened immune systems. Some simple precautions can greatly reduce the risk of transmission, such as avoiding rough play with cats, proper handwashing, and keeping cats’ nails trimmed. While Pasteurella infections should not be ignored, the health risks can be managed with reasonable care and awareness.

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