Granulomatous disease associated with Bartonella infection in 2 dogs

Shortly after removal of an engorged tick; from the left ear, a 4-year-old Greyhound was referred for evaluation of fever and a rapidly enlarging mass in the region of the left submandibular lymph node. Histopathologic evalua tion of the lymph node resulted in a diagnosis of severe granulomatous lymp hadenitis. An 11-year-old mixed-breed dog was referred for evaluation of a 6-week history of serous nasal discharge. Histologic examination of a surgi cal biopsy from a nasal mass indicated multifocal granulomatous inflammatio n with fibrosis. Serum samples obtained from both dogs were reactive by imm unofluorescent assay to Bartonella vinsonii subsp. berkhoffii antigens (rec iprocal titers of 128). Although Bartonella organisms were not isolated by lysis centrifugation blood culture, Bartonella DNA was amplified from tissu e samples obtained from each dog (lymph node biopsy from doe 1 and nasal bi opsy from dog 2) using primers that amplify a portion of the 16S rRNA gene followed by Southern blot hybridization using a genus-specific probe. Addit ionally, restriction fragment length polymorphism (RFLP) analysis of a Bart onella-specific citrate synthase gene product obtained from dog 2 resulted in a restriction pattern identical to Bartonella subsp. berkhoffii. This is the 1st report of granulomatous disease in dogs associated with Bartonella infection.