Ask the doctors: Man’s rare infection caused by dog saliva

Dear Doctor: My wife read that a man had his legs amputated after he got an infection from being licked by his dog, and now she’s freaking out. She’s afraid to even touch our dog anymore, lest it somehow get saliva on her. Please talk some sense into her.

Dear Reader: We can understand your wife’s initial sense of alarm regarding this story and suspect her reaction has been shared by quite a few others. The idea that just a lick from a beloved family pet can have such dire consequences is indeed disturbing. But before we get to the specifics, we’re glad to offer your wife reassurance that what happened in this case is extremely rare.

According to news reports, a 48-year-old man from Wisconsin was rushed to the hospital after symptoms similar to the flu – fever, vomiting, and aches and pains – quickly escalated. His fever spiked high enough that he became delirious, and bruises suddenly began to appear on his limbs, face and torso. The doctors in Wisconsin fought the infection with antibiotics for a week but were unable to stop its progress. In order to save the man’s life, parts of his legs and hands had to be amputated. The man was diagnosed with a rare blood infection caused by the bacterium Capnocytophaga canimorsus, which is found in the saliva of many healthy dogs. Prior to becoming ill, the man had contact with several dogs, including the family pet.

The vast majority of the time, Capnocytophaga isn’t harmful to humans. In rare instances, however, an infection with the bacterium can cause the immune system to go into overdrive. This happens most often in individuals whose immune systems have been weakened due to certain medical conditions like HIV or lupus, chemotherapy drugs or having had a splenectomy.

Transmission of Capnocytophaga canimorsus most commonly occurs via a dog bite, and less often through close contact in which saliva may be transferred. Although cats are also carriers of the bacterium, infection is most often linked to dogs.

Most people who become ill due to Capnocytophaga will begin to exhibit symptoms between three and five days after contact. In some cases, it can be as fast as one day, and can take up to two weeks. Symptoms of illness can include:

The formation of small blisters around the bite wound, sometimes beginning within an hour of the bite

Pain, swelling, redness or pus at the site of the wound

Elevated temperature, which may spike to a high fever

Stomach pain, often accompanied by diarrhea

Nausea and vomiting

Headache, sometimes accompanied by confusion

Aches and pains in the muscles and joints

If you have any of these symptoms following a dog bite, seek immediate medical help. In fact, any time that you get bitten by an animal, you should first thoroughly wash the area with soap and water, then immediately see a doctor. Not only is there the risk of infection, but animal bites can put you at risk for rabies as well.