cat scratch disease

Cat Scratch Disease | calico maine coon cat sitting on bed scratching himself
Posted by Dr. Kim Smyth on Mar 09 2012

Sorry, Ted Nugent fans – this blog is NOT dedicated to his 1977 hit song of the same name. Instead, we’ll be talking about the condition known as cat scratch fever (but feel free to play your old Nugent record while reading it)!

The disease is actually called cat scratch disease, and it is caused by infection with the bacterium Bartonella henselae. The disease is harbored in cats but spread by fleas, so now you have one more reason to be vigilant about your cat’s flea and tick control.

Cat scratch disease progress

The disease process goes like this: A cat (let’s call him Max) carries Bartonella henselae and is also unlucky enough to have a case of terrible fleas. Poor Max scratches a particularly itchy spot behind his ear and inadvertently picks up flea dirt under his toe nail. If you’re not familiar with flea dirt, it’s the tiny black flecks you find in the fur of pets with fleas. Those flecks are actually flea feces, and it’s made up of the host’s blood. In Max’s case, this flea dirt also carries the bacterium Bartonella henselae.

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Thankfully, his owner has just realized that Max is riddled with fleas and attempts to apply his topical flea prevention. During the process, Max scratches his owner, thereby transmitting the disease to him through the infected flea dirt.

Max might also become annoyed at another cat and scratch him, transmitting the disease to his feline friend and making him into a carrier. Let’s just hope his friend’s owner is keeping up with his flea medication!

For Max’s owner, who is a healthy person, cat scratch disease is an inconvenience, but not life-threatening. Generally, the scratch site will develop redness and then two to three weeks later, Max’s owner’s local lymph nodes will swell, and he will get a fever. Most of the time, these symptoms will resolve on their own. However, in people with compromised immune systems, cat scratch disease has more serious consequences.

Correlating medical issues

Max’s infection with Bartonella henselae is still not completely understood. Cats who are infected with the disease generally don’t show any symptoms, but several illnesses seem to be correlated with infection. For instance, plasma cell stomatitis, an oral disease, has been linked to Bartonella infection, but questions remain as to whether this is because there is such a high incidence of infection or not. In warm climates where fleas are prevalent, up to 40 percent of cats may test positive for Bartonella, making it difficult to prove if there are associations between it and other concurrent diseases.

Testing for Bartonella further complicates the issue, as there is no one test that diagnoses positive cases 100 percent of the time.

As with so many other things, when it comes to disease in our pets, prevention is key. If your cat does not have fleas, he cannot transmit the disease, even if he has it. By keeping up-to-date on your cat’s flea prevention, you ultimately keep yourself safe, too.

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