More information is emerging about the role of Bartonella vinsonii subspecies berkhoffi. Of 24 seropositive dogs that were seronegative for other tick-transmitted infection agents: 5 had autoimmune hemolytic anemia (AIHA) and 3 had granulomatous meningoencephalitis (GME). This indicates that Bartonella may be an organism contributing to immune system deregulation leading to either AIHA or GME. Dogs also have been diagnosed with uveitis secondary to infection with this Bartonella sub-species.

Bartonella has recently been shown to be a common cause of infective endocarditis in dogs in northern California (7 different spp. of Bartonella have been documented to cause endocarditis in dogs to date.) Concurrent Bartonella vinsonii and Babesia canis infection has been documented in a dog with non-regenerative anemia and persistent marked thrombocytopenia.

Convincing evidence of Bartonella infection is present for the following illnesses:

• Endocarditis
• Peliosis hepatitiss (B. henselae)
• Granulomatous inflammatory disease
• Rhinitis
• Liver disease
• Uveitis

Bartonella spp, have possible roles in:

• Initiating some cases of AIHA
• Neutrophilic meningitis
• GME
• Polyarthritis
• Thrombocytopenia

Seroprevalence of Bartonella vinsonii subsp. berkhoffi infection:

• Healthy dogs
• Most are seronegative
• Seroprevalence in healthy dogs in SE USA is 1-2%
• Sick dogs
• Seroprevalence is ~ 4%

Treat dogs that are seropositive for Bartonella vinsonii subsp. berkhoffi with azithromycin.

• Become seronegatiove rapidly; clinical signs of illness resolve.

Seroprevalence of Bartonella henselae in dogs is higher than seroprevalence to B. vinsonii, and may play an important role in illness in dogs.

• Healthy dogs ~ 10%
• Sick dogs ~ 25%

Suspected clinical illness associated with B. henselae infections:

• Polyarthritis
• Neurological disease
• AIHA
• Peliosis hepatitis
• Thrombocytopenia

Another species of Bartonella that infects dogs is presently being identified.