This is a severe infection due to Capnocytophaga canimorsus, a gram-negative bacteria found worldwide and known to be a part of the normal mouth flora of dogs and cats.

Though rare, the classic presentation follows inoculation of the organisms in the setting of a dog bite to a susceptible host (immunocompromised, cirrhotic, asplenic, or with alcohol use disorder, classically) resulting in severe gram-negative sepsis marked by purpura fulminans or gas gangrene. Disease is most common in older men, generally between 50 and 70 years of age.

Fever is common. Patients may also complain of rigors. The illness may be associated with hypotension, altered mental status, vomiting, diarrhea, and abdominal pain. Rash is commonly seen. There is no rash that is pathognomonic for the infection. The rash may be petechial, macular, or maculopapular. In the most severe cases, disseminated intravascular coagulation may occur and be associated with purpura fulminans or even gangrene. Patients can present with severe multiorgan disease and septic shock. In such cases, mortality rates can be as high as 80%.

Other reported complications include hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and adrenal hemorrhage.

Risk factors for severe, life-threatening infection include a history of splenectomy, functional asplenia, immunosuppression, cirrhosis, or alcohol abuse. A careful exposure and occupational history should be obtained to ascertain if the patient has any contact with dogs or cats or works with animals.

Laboratory findings include leukocytosis, thrombocytopenia, hematologic abnormalities consistent with disseminated intravascular coagulation, and elevated creatinine.

Diagnosis depends on isolating the organism from a sterile site including blood. Antibiotic therapy is necessary for treatment.

Of note, Capnocytophaga canimorsus does occasionally cause meningitis and endocarditis.