Capnocytophaga canimorsus is a type of bacteria that exists in the mouths of healthy dogs and cats. It is rod shaped and is able to grow rapidly under the right conditions. This bacteria can cause sepsis in people after an animal bite. This pathogen has a unique shape and outer layer, and can cause severe illness if not treated quickly and effectively.

This organism is a gram-negative bacillus, meaning it does not retain the colored die used in a laboratory gram stain test. This test helps to identify different types of bacteria. Gram-negative bacteria have a fatty outer layer that can make them resistant to antibiotics such as penicillin. For this reason, treating diseases caused by this type of bacteria are far more difficult.

Since the disease caused by capnocytophage canimorsus can be transferred from animals to humans, it is known as a zoonotic disease. This sepsis can be fatal to humans, and may be misdiagnosed since the symptoms often vary. Known signs of Capnocytophaga canimorsus sepsis are severe diarrhea, vomiting, abdominal tenderness, high blood pressure, and rapid heart rate. Patients may also experience high fevers, organ failure, cardiac arrest and coma.

The people most susceptible to Capnocytophaga canimorsus infection are those with limited or absent spleen function. These asplenic patients may have had their spleen removed due to trauma, illness or genetic disorders, or in cases where spleen function makes another medical condition worse. People who are immunocompromised due to illness or age are also more likely to be affected after a dog bite. As a result, any person with a compromised immune system is advised not to own a dog.

It is not always necessary for an animal bite to occur for Capnocytophaga canimorsus to be transmitted. In one case, a man with a history of spleen removal fell onto his hands in a recent accident. He had minor open wounds on his hands that were subsequently licked by a family member's dog. This dog's mouth harbored the bacteria, and subsequently the man experienced sepsis. He was, however, able to recover after timely antibiotic treatment.

While septicemia from a dog bite is relatively rare, it is a serious condition that can travel quickly through the blood stream and impact the entire body. A number of different antibiotics, including doxyycline and clindamycin, can be used in the treatment of capnocytophaga canimorsus sepsis. Patients may also benefit from blood and plasma transfusions in more severe cases of the infection.