Comparison of bronchoalveolar lavage fluid examination and other diagnostic techniques with the Baermann technique for detection of naturally occurring Aelurostrongylus abstrusus infection in cats.

OBJECTIVE: To evaluate the diagnostic sensitivity and specificity of bronchoalveolar lavage (BAL) fluid examination and other diagnostic techniques, compared with the use of the Baermann technique performed on fecal samples as the reference standard, for detection of naturally occurring Aelurostrongylus abstrusus infection in a population of cats.
DESIGN: Cross-sectional study. SAMPLE POPULATION: Cadavers of 80 semiferal domestic cats. PROCEDURES: BAL fluid collection and analysis, necropsy, examination of fecal samples and minced lung tissue via the Baermann technique, fecal sedimentation-flotation, and histologic examination of lung tissue were performed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of A abstrusus infection were calculated.
RESULTS: On the basis of fecal Baermann test results, prevalence of infection was 13.8%. Sensitivity (NPV) of tests was as follows: Baermann technique on minced lung tissue, 81.8% (97.2%); fecal flotation-sedimentation, 63.6% (94.5%); stereomicroscopic examination of BAL fluid combined with cytologic examination of BAL fluid, 54.5% (93.2%); stereomicroscopic examination of BAL fluid alone, 45.4% (92.0%); cytologic examination of BAL fluid alone, 36.4% (90.8%); histologic examination of lung tissue, 45.4% (91.8%); and gross lung appearance, 36.4% (90.8%). Specificity and PPV of all tests were 100%, with the exception of histologic examination of lung tissue (specificity, 97.1%; PPV, 71.4%), which identified infected cats that had negative fecal Baermann test results. CONCLUSIONS AND CLINICAL RELEVANCE: The Baermann technique was the most sensitive test for detection of A abstrusus infection. On the basis of the prevalence of 13.8% in this study, A abstrusus infection should be considered in pet cats.