How to perform a transtracheal aspirate in horses for diagnosis of lower respiratory tract disease.

Objective: To describe indications for and demonstrate the technique to perform a transtracheal aspirate in horses. Transtracheal aspirate is indicated to collect samples for cytology and bacteriologic culture in cases of suspected pneumonia or other lower respiratory tract disease.

Animals: 1 healthy university-owned horse was used for demonstration purposes. Images of clinical case samples from the University of Illinois Veterinary Teaching Hospital are shown.

Methods: The horse is restrained and sedated with detomidine or xylazine to facilitate restraint and butorphanol to minimize coughing. The ventral neck is clipped and aseptically prepared. The site of planned puncture proximal to the bifurcation of the sternocephalicus is anesthetized with lidocaine. Two to three 30-mL syringes are filled with saline aseptically. A stab incision is made with a No. 15 blade to the depth of the trachea. The trocar is advanced between tracheal rings on midline, the stylet removed, and the aspiration catheter advanced through the trocar to the level of the proximal horizontal trachea. Sterile saline (30 mL) is infused rapidly, and suction is applied to the syringe while slowly withdrawing the catheter until fluid is retrieved. The catheter and trocar are withdrawn and the puncture site covered with antimicrobial ointment or a light bandage.

Results: Samples are collected in a plain tube for bacteriologic culture and EDTA for cytology. The visual appearance of purulent effluent confirms severe pneumonia.

Clinical Relevance: Transtracheal aspirate is minimally invasive and simple to perform with available kits. Samples provide valuable information to guide treatment decisions and selection of antimicrobials for horses with suspected lower respiratory tract disease.