Evaluation of Chlamydophila psittaci infection and other risk factors for atherosclerosis in pet psittacine birds.

Objective: To determine whether the presence of Chlamydophila psittaci antigen, plasma cholesterol concentration, diet, sex, species, and age are risk factors for the development of atherosclerosis in pet psittacine birds.
Design: Retrospective case-control study.
Animals: 31 psittacine birds with atherosclerosis (study birds) and 31 psittacine birds without atherosclerosis (control birds).
Procedures: Necropsy reports were reviewed, birds with a histopathologic diagnosis of atherosclerosis were identified, and available medical records were reviewed. Signalment, history, clinicopathologic findings, and other relevant data were recorded and evaluated. Control birds did not have atherosclerosis and were chosen by both convenience sampling and population demographics. Histologic sections of great vessels from all birds (study and control birds) were reviewed and then submitted for immunohistochemical staining for the presence of C psittaci antigen.
Results: Result of immunohistochemical staining for C psittaci antigen in blood vessels was significantly associated with atherosclerosis. After adjusting for age, species origin, and type of illness, the odds of atherosclerosis was 7 times as high for birds with positive immunohistochemical staining for C psittaci antigen, compared with that of birds with negative immunohistochemical staining. Study birds and control birds differed significantly only with respect to plasma cholesterol concentrations. The median plasma cholesterol concentration of study birds (421 mg/dL) was significantly higher than that of control birds (223 mg/dL).
Conclusions and Clinical Relevance: Infection with C psittaci and a high plasma cholesterol concentration may be risk factors for developing atherosclerosis in pet psittacine birds.