This article covers the techniques for obtaining a bronchial wash and broncho alveolar lavage from small animals. These techniques are relatively simple and can provide more information on lower airway respiratory conditions.


Unless there is overt evidence of upper airway disease, a Bronchial Wash or a Broncho-Alveolar Lavage (BAL) will help establish a definitive diagnosis in lower airway respiratory conditions. When an endoscope is available BALs are superior.


(1) WITHOUT ENDOSCOPE- Bronchial Wash Technique,
Use a cuffed endotracheal tube. Intubate dog/cat as aseptically as possible under a short acting, light, general anaesthetic and inflate the cuff. Measure the distance from the anterior tip of the endotracheal tube to the carina. Using this as a guide , pass a urinary catheter gently via the endotracheal tube, taking care not to use excess force and damage bronchi. Use sterile saline or lactated Ringers as the flush solution. As a rule of thumb 0.5ml of solution per kg bodyweight divided into 2-3 flushes can be safely used. Using an appropriately- sized syringe, flush the liquid into the lungs and recover immediately after each flush, by sucking back on the syringe. Commonly only 10-15% of the solution is recovered. It is best to keep the animal anaesthetised lightly enough to have a cough reflex as this helps recovery of sample after input.
(2) WITH ENDOSCOPE- Broncho Alveolar Lavage
Pass the scope . A sterile endoscopic catheter is the threaded down the endoscope and visualised as the endoscope occludes the selected airway. Flush fluid and recover as above, commonly 20-30% of the volume flushed is retrieved.
Make direct smears in clinic. If you have a centrifuge , spin down and also make smears from the sediment. Take samples for cultures before contaminating with non-sterile laboratory equipment. Smears from samples which contain a lot of mucus are best made by the horizontal/pull apart method and rapidly waving to help drying. Lie a slide on top of a second slide onto which a "glob" of mucus has been pipetted, let the mucus spread out and the pull apart horizontally. Submit left-over material to the labaratory as a liquid in EDTA.

Chris Belford is a RCVS specialist in clinical pathology. Chris has recently established Cytopath, a new veterinary laboratory providing a quality service to vets in the UK. Chris can be contacted; by phone; +44 (0)1352 840 888 or via the editor of Vet On-Line.
Chris welcomes enquiries from vets worldwide.

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