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Trachea: collapse
Introduction
- Cause:
- Uncommon condition; primary tracheal collapse → obstruction of the tracheal lumen due to dorsoventral flattening of trachea probably caused by abnormal cartilage matrix in ponies and miniature horses.
- Secondary tracheal collapse → obstruction of the tracheal lumen secondary to trauma or compression by extraluminal causes, or collapse of the cricotracheal ligament (CTLC) reducing the airway diameter where the cricoid cartilage connects to the trachea.
- Signs: respiratory stridor, dyspnea, cyanosis, poor performance.
- Diagnosis: endoscopy and radiography.
- Treatment: depends on cause and severity; treat underlying cause; conservative therapy; surgical correction.
- Prognosis: fair if normal tracheal lumen size and shape is restored.
Presenting signs
- Respiratory noise often worse in warm weather and on exercise.
- Reduced performance.
Acute presentation
- Respiratory stridor, tachypnea, dyspnea, cyanosis, tachycardia, hyperthermia.
Geographic incidence
- Worldwide.
Age predisposition
- Primary tracheal collapse: >10 years.
- Secondary tracheal collapse: none.
- CTLC: <6 years.
Breed/Species predisposition
- Tracheal collapse: small ponies, especially Shetland Shetland Pony, Miniature horses American Miniature Horse, but also reported in larger breeds of horses and ponies, as well as donkeys.
- Secondary tracheal collapse: none.
- CTLC: only been reported in Thoroughbreds Thoroughbred.
Cost considerations
- Surgical correction.
Special risks
- Tracheostomy and/or endotracheal tube placement in cases of primary tracheal collapse with severe flattening of the trachea have been reported to result in fatal laceration of the carotid artery and esophagus.
Pathogenesis
Etiology
Primary collapse
- Paresis of the trachealis muscle.
- Mineralization of the tracheal cartilages.
- Defective tracheal cartilage.
- Slack and elongated dorsal tracheal ligament.
- Lower airway disease creating abnormal negative pressure, eg RAO, SPAOPD, bacterial pneumonia.
Secondary collapse
- Trauma resulting in tracheal damage.
- Extraluminal compression, eg neoplasia.
Collapse of the cricotracheal ligament
- Thought to result from a congenitally abnormally wide space between the cricoid cartilage and the 1st tracheal ring.
- Or, as a result of abnormally increased negative pressure within the trachea during exercise.
Predisposing factors
Specific
- Primary tracheal collapse: lower airway disease creating abnormal negative pressure.
- CTLC: all reported cases have concurrent pharyngeal lymphoid hyperplasia.
Pathophysiology
- Primary tracheal collapse: cartilage defect (failure of normal glycosaminoglycans and glycoprotein synthesis) → structurally weaker matrix (demonstrated in dogs).
Timecourse
- Primary tracheal collapse is often intermittent initially and may be associated with stressful events, exercise, dusty environment and eating, but the severity of clinical signs often increases over time.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Graham S B et al (2010) Treatment of traumatic tracheal collapse with extraluminal titanium mesh screens. Equine Vet Educ 22 (11), 557-563 VetMedResource.
- Epstein K (2008) Tracheal collapse: Are there other options for treatment? Equine Vet Educ 20 (2), 91-92 WileyOnline.
- Franklin S H (2008) Dynamic collapse of the upper respiratory tract: A review. Equine Vet Educ 20 (4), 212-224 VetMedResource.
- Wong D M, Sponseller B A, Riedesel E A, Couetil L L & Kersh K (2008) The use of intraluminal stents for tracheal collapse in two horses: Case management and long-term treatment. Equine Vet Educ 20 (2), 80-90 VetMedResource.
- Couteil L L, Gallatin L L, Blevins W & Khadra I (2004) Treatment of tracheal collapse with an intraluminal stent in a Miniature horse. JAVMA 225 (11), 1727-1732 PubMed.
- Siger L et al (1998) Tracheal stenosis and collapse in horses. Comp Cont Educ 20 (5), 628-635 VetMedResource.