Newly named in 1989, Capnocytophaga canimorsus is a bacterial pathogen found in 
the saliva of healthy dogs and cats, and is transmitted to humans principally by 
dog bites. This review compiled all laboratory-confirmed cases, animal sources, 
and virulence attributes to describe its epidemiology, clinical features, and 
pathogenesis. An estimated 484 patients with a median age of 55 years were 
reported, two-thirds of which were male. The case-fatality rate was about 26%. 
Its clinical presentations included severe sepsis and fatal septic shock, 
gangrene of the digits or extremities, high-grade bacteremia, meningitis, 
endocarditis, and eye infections. Predispositions were prior splenectomy in 59 
patients and alcoholism in 58 patients. Dog bites before illness occurred in 
60%; additionally, in 27%, there were scratches, licking, or other contact with 
dogs or cats. Patients with meningitis showed more advanced ages, higher male 
preponderance, lower mortality, and longer incubation periods after dog bites 
than patients with sepsis (p < 0.05). Patients with prior splenectomy presented 
more frequently with high-grade bacteremia than patients with intact spleens 
(p < 0.05). The organism possesses virulence attributes of catalase and 
sialidase production, gliding motility, cytotoxin production, and resistance to 
killing by serum complement due to its unique lipopolysaccharide. Penicillin is 
the drug of choice, but some practitioners prefer third-generation 
cephalosporins or beta-lactamase inhibitor combinations. C. canimorsus has 
emerged as a leading cause of sepsis, particularly post-splenectomy sepsis, and 
meningitis after dog bites.