Transtracheal aspiration in the horse: a photo essay.

Transtracheal aspiration is used to obtain samples for culture and cytologic examination of respiratory tract secretions and exudates. A 15-cm-long area of the ventral midcervical region is surgically prepared, a small site infiltrated SC with 2-3 ml lidocaine, and a stab incision made in the skin. A trocar with cannula is inserted through the incision and annular ligament into the trachea and the trocar removed. An 8-Fr polypropylene catheter is inserted about 35-40 cm down the trachea and attached to a 30-ml syringe, containing 20 ml sterile saline, with a 3-way stopcock . The saline is rapidly injected and a 3- to 4-ml sample is aspirated after the horse coughs and as the catheter is slowly withdrawn. The catheter and cannula are withdrawn, the area covered with antibacterial ointment and gauze sponges, and elastic tape applied. Complications are rare but include SC emphysema or infection, pneumomediastinum and cartilage ring damage.