Abstract:Nasal or nasopharyngeal swabs are often employed for etiological diagnoses of bovine respiratory disease complex (BRDC), but transtracheal wash (TTW) can provide samples to assess the microbiological status of the lower respiratory tract because there is no contamination of the microorganisms from the upper respiratory airways. In large animals, a TTW is performed by means of angiocatheter or trocar, where a rubber tube or urinary catheter can be inserted. Although sterile instruments are commonly recommended, there is little practical information on the available tools for TTW. This case series reports the use of a disposable sterile single lumen polyurethane and plastic-coated venous catheter (Cavafix® Certo with Splittocan®, BBraun, Milan, Italy) to perform TTW in dairy calves affected by BRCD. Thirty-seven Holstein-Friesian calves with BRDC, admitted to the veterinary teaching hospital, underwent a TTW. After sedation of the calf, the disposable catheter was inserted into the tracheal lumen and 20 mL of sterile saline solution was injected and re-aspirated. The procedure was always well tolerated and allowed to isolate the pathogenic microorganisms in 30 cases (81%). A single pathogenic microorganism was isolated in 23 cases, while in 7 cases, multiple isolations were performed. The most frequently isolated pathogens were Pasteurella multocida (13 cases, 35.14%) and Mycoplasma bovis (11 cases, 29.76%). Parainfluenza type 3 virus (PI-3) and bovine respiratory syncytial virus (BRSV) were both isolated in 4 cases. In 7 calves, already treated with antibiotics before hospitalization, the samples resulted sterile. In cattle the most employed tools to perform TTW are represented by urinary catheters or polyethylene tubes but they are not equipped with protective devices, that preserve sterility during the procedure. The characteristic plastic sheath covering Cavafix® Certo catheter avoids contamination during the entire procedure, increasing thereby the asepsis level of this technique. The use of Cavafix® Certo catheter is a simple, effective, and safe technique that can help to maintain asepsis throughout the procedure, especially in field conditions.