Tracheal collapse

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Tracheal collapse in a dog[1]
Same dog as above after placement of intratracheal nititol stent[1]

Tracheal collapse is a degenerative respiratory disease characterized by weakening of the tracheal ring cartilages or tracheal hypoplasia resulting in flattening and flaccidity of the trachea.

Dogs with brachycephalic syndrome such as the Pug and Pekingese are predisposed to this disease, as well as other airways diseases such as stenotic nares, elongated soft palate, everted laryngeal saccules[2] and bronchomalacia.

In affected dogs, the tracheal cartilage usually collapses in a dorsoventral direction with the cervical trachea collapsing during inspiration and the thoracic trachea collapsing during expiration[3].

Clinically affected dogs typically present with a chronic, paroxysmal honking cough[4][5], reduced tidal breathing flow-volume[6], varying degrees of dyspnea, cyanosis, syncope and a predisposition to developing aspiration pneumonia.

Radiography and ultrasonography are traditionally used to diagnose this condition[7], but fluoroscopic and tracheoscopy are considered to be the most sensitive methods for diagnosing tracheal collapse[8].

Radiographs usually show varying degrees of flattening of the trachea, bronchial collapse, bronchomalacia and pneumonitis[9]. Dogs with bronchomalacia are significantly more likely to display normal airway cytology and to have mitral valve endocardiosis and cardiomegaly than dogs without airway collapse[10].

A differential diagnosis would include heartworm disease, thyroid carcinoma and bronchial carcinoma.

Acute tracheal collapse should be treated as a medical emergency, requiring oxygen therapy and aminophylline[11]. Worsening cases may required elective tracheotomy to assist respiration.

Treatment is usually palliative in most cases with drugs such as prednisolone or stanozolol[12], however, the response to treatment with antitussives, antibiotics, bronchodilators, corticosteroids, sedatives, and oxygen, as well as other forms of medical management, including weight reduction, exercise restriction, and a non-smoking environment, usually is limited[13].

In the terminal stages of this disease, when dyspnea becomes the dominating sign and is no longer manageable with medical treatment, a surgical procedure is necessary[14].

A number of methods are available such as intratracheal stents inserted via bronchoscopy[15] are popular but have been associated with several complications, including stent migration and shortening as well as granuloma formation[16].

Cervical extraluminal prosthetic rings or spiral prostheses[17] are growing in popularity, surgical reconstruction of thoracic tracheal segments is associated with a high mortality rate[18][19].

The prognosis in mildly affected dogs is good without surgical intervention, but guarded in dogs that have severe respiratory dyspnea require surgical maangement.

References

  1. 1.0 1.1 Kim JY et al (2008) The safety and efficacy of a new self-expandable intratracheal nitinol stent for the tracheal collapse in dogs. J Vet Sci 9(1):91-93
  2. Torrez CV & Hunt GB (2006) Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia. J Small Anim Pract 47:150–154
  3. Kealy JK & McAllister H (2005) Diagnostic Radiology and Ultrasonography of the Dog and Cat. 4th ed. St.Louis: Saunders. pp:173–295
  4. Ettinger SJ & Kantrowitz B (2005) Diseases of the trachea. In: Ettinger SJ, Feldman EC, editors. Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat. 6th ed. St. Louis: Saunders. pp:1217–1232
  5. Harvey CE (1983) Review of results of airway obstruction surgery in the dogs. J Small Anim Pract 24:555–559
  6. Pardali D et al (2010) Tidal breathing flow-volume loop analysis for the diagnosis and staging of tracheal collapse in dogs. J Vet Intern Med 24(4):832-842
  7. Rudorf H et al (1997) Use of ultrasonography in the diagnosis of tracheal collapse. J Small Anim Pract 38:513–518
  8. Kneller SK (2002) The Larynx, Pharynx and Trachea. In: Thrall DE, editor. Textbook of Veterinary Diagnostic Radiology. 4th ed. Philadelphia: Saunders. pp:323–328
  9. De Lorenzi D et al (2009) Bronchial abnormalities found in a consecutive series of 40 brachycephalic dogs. J Am Vet Med Assoc 235(7):835-840
  10. Johnson LR & Pollard RE (2010) Tracheal collapse and bronchomalacia in dogs: 58 cases (7 /2001-1 /2008). J Vet Intern Med 24(2):298-305
  11. Radlinsky MA & Fossum TW (2000) Tracheal collapse in a young boxer. J Am Anim Hosp Assoc 36(4):313-316
  12. Adamama-Moraitou KK et al (2011) Conservative management of canine tracheal collapse with stanozolol: a double blinded, placebo control clinical trial. Int J Immunopathol Pharmacol 24(1):111-118
  13. Johnson L (2000) Tracheal collapse. Diagnosis and medical and surgical treatment. Vet Clin North Am Small Anim Pract 30:1253–1266
  14. Glaus TM et al (2011) Placement of intraluminal stents for treating tracheal collapse in dogs. Schweiz Arch Tierheilkd 153(11):505-508
  15. Durant AM et al (2012) Use of nitinol stents for end-stage tracheal collapse in dogs. Vet Surg 41(7):807-817
  16. Radlinsky MG et al (1997) Evaluation of the Palmaz stent in the trachea and mainstem bronchi of normal dogs. Vet Surg 26:99–107
  17. Becker WM et al (2012) Survival after surgery for tracheal collapse and the effect of intrathoracic collapse on survival. Vet Surg 41(4):501-506
  18. Jeong SH & Jeong SW (2004) Application of new external total ring prostheses made by drip chamber of intravenous administration set in normal dogs. Korea J Vet Res 44:137–141
  19. Lee CH et al (2000) Modified extraluminal prostheses applied to the canine tracheal collapse. Korean J Vet Clin Med 17:266–269