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What's New with Tracheal Stenting for Collapsing Trachea Practice points Surgical management is a salvage procedure for tracheal collapse 65-78% of dogs with tracheal collapse respond to medical therapy Tracheal stenting carries an approximate 50% complication rate Approximately 90% of owners that have tracheal stenting performed were pleased with the outcome if they were sufficiently educated beforehand Tracheal collapse is a progressive, irreversible condition. This collapse is typically in a dorsoventral fashion and is associated with the classic “goose honk” cough. The collapse can be very minor to life threatening due to airway obstruction, but progressive. Middle-aged toy and small breed dogs, especially Pomeranians, Yorkshire Terriers, Miniature Poodles, and Pugs are the most common breeds affected. In a survey of 100 dogs with tracheal collapse, 24% had initial clinical signs by approximately 6 months of age. Congenital and acquired components have been proposed as causes for tracheal cartilage weakness and factors such as obesity, environmental allergens, cigarette smoke, and kennel cough exacerbate clinical signs. Histopathologic evaluation of the tracheal cartilage in affected animals is found to be hypocellular, with a reduction in glycoprotein and glycosaminoglycan that is associated with decreased water retention within the matrix. The decreased water retention leads to increased compliance and decreased rigidity of the tracheal cartilage. A vicious cycle of cough and perpetual inflammation ultimately leads to loss of normal tracheal epithelium and replacement with a fibrous membrane epithelium, followed by formation of squamous metaplasia and reduction of ciliated cells with secretion of increasingly viscous mucus. A grading system is used to classify the degree of tracheal collapse but is only accurate when describing tracheobronchoscopic findings. Grade I collapse is laxity of the dorsal tracheal membrane, resulting in 25% luminal collapse. Grade II collapse is loss of cartilage rigidity and further laxity of the tracheal membrane, resulting in 50% luminal collapse. Grade III collapse is flattening of the tracheal cartilages, resulting in 75% luminal collapse. Grade IV collapse is 100% loss of luminal integrity. Medical management of tracheal collapse is variable but often multimodal approach yields the best results. The most beneficial therapy for dogs with tracheal collapse is keeping them at a good body condition score (ideally 4/9). Weight loss is a key component to medical management. An example of one treatment regimen could be: Cerenia daily for 5 days then EOD, 1/2 lomotil, doxepin 10mg bid and continue with hydrocodone or butorphanol bid - tid, and have low dose acepromazine ie 2.5mg bid for stressful days. Cerenia has significant antitussive effects. Doxepin reduces anxiety and has some soothing effects on larynx, lomotil has opioid effects to reduce cough, and acepromazine helps with anxiety and compliments opioids. Add in Adequan injections twice a week for 4 weeks then once a month as a maintenance medication. The Adequan may improve cartilage in trachea due to the decrease in glycosaminoglycans and water content. Since Cerenia can be expensive one way to make it more economical is to use the 24 mg tablets and cut them into ¼ - ½ tablets. This is just one example of medications used to treat tracheal collapse and each patient can respond differently to different protocols. Surgical options for tracheal collapse are considered salvage procedures because of high complication rates and often times the tracheal collapse can continue into the lower airways where there are no surgical options. Reported surgical techniques to restore airway patency and reduce airway resistance include tracheal ring chondrotomy, plication of the dorsal tracheal membrane, prosthetic mesh reconstruction and extralumanial prosthetic supports. All of these surgeries carry a high complication rate (>50%). In recent years intraluminal tracheal stenting has been developed using a metallic mesh stent that retains the preformed shape. These stents are made out of metal alloys usually out of nitinol (an alloy of nickel and titanium). The intraluminal tracheal stents have gained popularity due to short anesthetic time, immediate improvement in clinical signs and the ability to noninvasively place the stent within the cervical or thoracic regions. Even though intraluminal stenting carries a high complication rate (approximately 50%), stenting has been more successful than other surgeries. The most common complication is a residual cough (61% of patients). Other complications include stent fracture, aspiration pneumonia, stent migration, stent collapse, breakage and deformation of the stent, excessive granulation tissue, coughing, pneumomediastinum, pneumonia and death. Tracheal stenting can be placed under fluoroscopy or placed via endoscope. In a recent study 90% of owners with a dog with endstage tracheal collapse that chose to have the procedure performed were pleased with the outcome if they were sufficiently educated beforehand. Unless having the procedure performed at a large institution where they can carry a large inventory of stents, the patient has to undergo two anesthetic episodes. One for the measurement of the stent, the patient has to be anesthetized to get the appropriate positive pressure tracheal expansion. The second anesthetic episode is for the placement. Typically the stents can be ordered and delivered overnight express shipping so the placement of the stent can be performed within 24 hours of the initial measuring. In summary tracheal stenting is a salvage procedure that carries a fair prognosis. As long as the owners are aware of the severity of the disease, if the patient has become refractory to medical management, and the owners are OK with the expense of the procedure and stenting, it can be a life saving procedure.