Tracheal collapse is a frequently encountered, progressive, chronic respiratory disease of middle-aged, small and toy-breed dogs. Yorkshire terriers, Pomeranians, poodles and Chihuahuas are reported to be the most commonly affected breeds. Tracheal collapse is characterized by a dorsoventral flattening of the trachea secondary to weakness of the tracheal cartilaginous rings and flaccidity of the dorsal tracheal membrane.

This results in a narrowing of the tracheal lumen that can range from mild to severe and can occur anywhere along its length. The cervical trachea and thoracic inlet have been described as the most commonly affected regions; however, collapse of the intrathoracic trachea, carina and mainstem bronchi can occur. The underlying pathogenesis of the disease has been the object of numerous studies and has yet to be determined. Tracheal ring cartilage of affected dogs shows markedly decreased amounts of chondroitin sulphate, calcium, glycoproteins and glycosaminoglycans. Congenital or acquired disruption of tracheal rings along with anomalies of the dorsal membrane ultrastructure may result in weakness, shape modification and inflammation, which may contribute to the degenerative process. A ‘W’ malformation has been identified in a number of Yorkshire terriers (other breeds can also be affected).

This tracheal malformation commonly occurs at the thoracic inlet and can result in misinterpretation of a mediastinal mass on standard thoracic radiographs. Clinical signs are worsened by exercise or excitement, but may be present at rest in severe cases. These signs generally include coughing, gagging, typical “goose honking” respiratory sounds, loud/raspy breathing and dyspnea. Dogs generally present with 2 categories of clinical signs: coughing/gagging and those who obstruct acutely and often need emergency treatment. The latter group often does not present any or very little coughing with intermittent dramatic obstructive episodes.

Diagnosis is based on clinical presentation, physical exam and is confirmed by various imaging techniques. Radiographs have been reported to correctly identify affected dogs in 59 to 84% of cases. Ideally, the collapsed trachea should be visualized under fluoroscopy to observe dynamic airway collapse during the different respiratory phases and most importantly during coughing.

Tracheobronchoscopy is a useful and sensitive tool in the diagnosis of tracheal collapse, allowing direct visualization of the tracheal lumen.

Initially, medical therapy is recommended and results in long-term resolution of clinical signs in greater than 80% of dogs. Medical management includes the use of antitussives, anti-inflammatories (corticosteroids are important), bronchodilators, oxygen supplementation and sedatives as needed. In dogs, for which appropriate medical management has not resulted in satisfactory results, tracheal stenting should be considered.

The use of various endoluminal stents has been described for the treatment of tracheal collapse in the dog. Use of endoluminal prosthesis for this condition was first reported by Leonard in 1978. Endoluminal stents share many advantages, including placement in extra- and intrathoracic portions of the trachea, a non-invasive placement, ease and rapidity of placement, quick and effective relief of clinical signs and a better adaptability to various diameters (trachea, bronchus).

When should I consider placing a stent for tracheal collapse?

Due to the expense, the reported short- and long-term complications and the need to continue medications in many patients, tracheal stenting is reserved for dogs that are unresponsive to conventional medical therapy and that have a seriously compromised quality of life. There is currently no evidence that early tracheal stenting slows progressive myelomalacia and should not be used prophylactically.¹

A recent retrospective study on tracheal stenting reveals lots of important information that can help both veterinarians and clients make the decision to stent or not to stent.² In the study, half of the dogs had a tracheal malformation and the other half presented for traditional tracheal collapse. Dogs with malformations tended to be younger (7 years) at the time of stenting than traditional collapse dogs (9 years). 75% of dogs undergoing stenting had positive bacterial airway cultures. Following tracheal stenting, 89% of dogs had improvement in goose-honking and loud breathing, 84% had improvement in dyspnea, but only 43% had improvement in cough. 95% of dogs continued to receive medication long term (antitussives and corticosteroids: concurrent bronchial collapse).

Complications: 19% stent fracture needing re-stenting, obstructive tissue ingrowth 17% (treated with antibiotics and sometimes needing restenting), 10% progressive tracheal collapse. Pneumonia/tracheal infection at some point during the long-term follow-up was found in 57% of patients and was mostly responsive to antibiotics.

Mean survival time was 1000 days. Cause of death was respiratory related in 77% of dogs.^2,3

Tracheal stenting is a useful procedure that can significantly restore quality of life to severely affected patients. Tracheal stenting does not cure these dogs and most remain symptomatic for cough and need long-term medical therapy. Tracheal stenting is recommended in patients with goose-honking, loud-breathing and obstructive episodes in patients unresponsive to medical therapy. Tracheal stenting is not a treatment for cough.

References

1.  Weisse C. Intraluminal tracheal stenting. In: Weisse C, Berent A, eds. Veterinary Image-Guided Interventions. Singapore: Wiley Blackwell; 2015;73–82.

2.  Weisse C, Berent A, Violette L, McDougall R, Lamb K. Short-, intermediate- and long-term results for endoluminal stent placement in dogs with tracheal collapse. J Am Vet Med Assoc. 2019;254(3):380–392.

3.  Ouellet M, Dunn ME, Lussier B, et al. Noninvasive correction of a fractured endoluminal nitinol tracheal stent in a dog. J Am Anim Hosp Assoc. 2006;42(6):467–71.