Bartonella species antibodies and hyperglobulinemia in privately owned cats.

Background: Bartonella species are zoonotic agents and primary pathogens in cats. Hyperglobulinemia has been associated with bartonellosis in humans and cats.

Hypothesis/objectives: To evaluate for associations between Bartonella species immunoglobulin G (IgG) antibodies and serum biochemistry panel results in privately owned cats.

Animals: 1,477 privately owned cats.

Methods: Residual sera were collected after biochemical evaluation for this prospective, cross-sectional serosurvey. Bartonella species IgG ELISA was performed with a cutoff value of ≥ 1 : 64. Stepwise logistic regression analysis was performed with the endpoint titer as the outcome variable. The final statistical model included age, albumin, ALP activity, ALT activity, bilirubin, creatinine, glucose, and globulin as covariates. Serum protein electrophoresis was performed with serum from 50 cats with and without antibodies to Bartonella species and hyperglobulinemia. Sera from cats seropositive to Bartonella species and with hyperglobulinemia were assessed for evidence of exposure to other infectious agents associated with hyperglobulinemia.

Results: Risk of seropositivity to Bartonella species was positively associated with the natural log of globulin concentration (OR = 11.90, 95% CI 6.15-23.02, P < .0001), and inversely associated with the natural log of glucose concentration (OR = 0.66, 95% CI 0.50-0.87, P = .004). Another explanation for hyperglobulinemia was not identified for most cats with Bartonella species antibodies. Hyperglobulinemia was primarily caused by polyclonal gammopathy in cats that were seronegative and seropositive for Bartonella species.

Conclusions and clinical importance: Hyperglobulinemia was significantly associated with seropositivity to Bartonella species. Testing for bartonellosis is warranted in cats with unexplained hyperglobulinemia and clinical or laboratory findings suggestive of bartonellosis.