OBJECTIVES

Bronchoalveolar lavage (BAL) is a valuable tool for the diagnostic evaluation of cats with lower respiratory tract disease. BAL is a minimally invasive procedure that provides samples from the lower respiratory tract. These samples can be evaluated cytologically and microbiologically for the evidence of inflammation, neoplastic cells, and infectious agents. The purpose of this retrospective study was to evaluate the clinical benefit of BAL on the etiological diagnosis and the subsequent treatment in cats with lower respiratory tract disease.

MATERIALS

The data in this study were collected from the case files of twenty-six cats presented with naturally occurring lower respiratory tract disease, between 1998 and 2001. Minimum databases were obtained for each cat and included history, clinical presentation, physical exam and diagnostic tests. The diagnostic tests performed before the bronchoalveolar lavage were: CBC, FeLV/FIV test and thoracic radiographs (lateral and dorsoventral views).

Bronchoalveolar lavage was performed using the sterile endotracheal tube technique. The cats were anesthetized with a combination of ketamine and diazepam intravenously at a low dose. Pure oxygen and isoflurane were then administered by facemask for five minutes to produce a depth of anesthesia enough to allow intubation. The anesthesia is maintained with inhaled isoflurane. The animals were positioned in lateral recumbency and an aliquot of warm saline solution with a volume of 3 ml/kg of body weight was instilled through a 1.8 mm diameter urinary catheter which was placed into the endotracheal tube over several seconds. The catheter was attached to a three-way stopcock, and the fluid from bronchi was carefully suctioned. Then the animals were positioned on the other side and the procedure was repeated in the same way. The samples were collected in a sterile way and submitted for bacterial culture and sensitivity, total nucleated cells and differential counts, and cytopathology.

RESULTS

On cytological examination, 14/26 cases presented a mixed inflammatory response (eosinophils, neutrophils, and macrophages); in 4 of them Aelurostrongylus sp. larvae were found; in 2 of them Toxoplasma gondii cysts were found; in 2 of them neoplastic cells consistent with carcinoma were found; in 6 of them positive cultures were found, and infectious bronchitis was diagnosed. 7/26 cases presented an eosinophilic inflammatory response (> 60-75% of cell population), consistent with feline eosinophilic bronchitis (feline asthma). 5/26 cases presented a normal inflammatory cell population (25% of cell population were eosinophils and macrophages). The combination of clinical signs and cytological results were consistent with eosinophilic bronchitis, idiopathic chronic bronchitis, or lipoid pneumonia.

CONCLUSION

BAL is an easy and safe procedure. It has the advantage over radiography to be more specific identifying the etiologic agent, as different etiologies have similar radiographic patterns. The only drawback is the need of general anesthesia, so that animals with severe respiratory distress are not candidates for this technique. Fluid collection gives a specific etiology of the disorder in more than 50% of cases and it aids in the election of a therapeutic protocol. It is a useful technique in chronic respiratory disorders with infectious (bacterial, fungal or parasitic) or neoplastic etiology. The bronchoalveolar lavage is also useful to evaluate the type of inflammatory response present, but this does usually not have great implications in the further treatment.