Horse Side Vet Guide ®

Equine Health Resource

Tracheal Wash, Trans-Tracheal Aspirate



Transtracheal wash (TTW) is a commonly used diagnostic procedure for the respiratory tract. It is most commonly used to try to isolate bacterial organisms causing pneumonia. It is performed in the standing (often sedated) horse.

The procedure for transtracheal wash involves clipping and sterilizing a square of skin overlying the trachea or windpipe on the front of the neck. Sterile gloves are worn by the vet to maintain sterility. A large needle is passed between the cartilage tracheal rings. A long plastic catheter is threaded a variable distance into the trachea. Sterile saline is injected and then withdrawn back into the syringe.

This fluid contains a sample of the tracheal fluid, Cytology (study of cells) can be performed on the fluid, and can indicate the type and degree of inflammatory response present. Fluid can be submitted to the laboratory for culture and sensitivity, allowing precise targeting of relevant organisms with specific antibiotics.


Because the catheter does not pass through the mouth (carrying bacteria from the mouth into the respiratory tract), TTW allows an uncontaminated sample to be obtained from the tract.

This allows for the identification of the significant organisms and choice of appropriate antibiotic.


TTW is not particularly helpful for the diagnosis of deep lung diseases. For that, bronchoalveolar lavage (BAL) is more helpful.

Author: Doug Thal DVM Dipl. ABVP


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