2) Diseases of the trachea Flashcards
Anatomy of the trachea
Anatomy and pathophysiology
- Semi-rigid, flexible tube, 35 – 45 C-shaped cartilages, bifurcates into the mainstem bronchi at Th4-Th5, cartilage-free dorsal membrane; ciliated columnar epithelium, goblet cells, mucus-secreting tubular glands
- Response to an insult is limited (mucus secretion, metaplasia, hyperplasia)
- Stenotic disease (collapse, hypoplasia) → increased airway resistance → hypoventilation → respiratory acidosis; chronic obstruction → pulmonary hypertension, cor pulmonale
History and physical exam - trachea
History and physical examination
- Coughing, noisy inspiratory sounds, wheezing expiratory sounds, “goose honk” cough
- Palpation of the neck: emphysema, collapse, mass (thyroid gland, haematoma, abscess)
• Cough can be elicited (laryngeal, tracheal irritation)
- Auscultation: over the larynx, trachea, lung
• Sounds are usually most intense near their site of origin
DIagnostic tests - trachea
Radiography
• LL and VD/DV; collapse, hypoplasia (Ø trachea / thoracic inlet > 0.2, 0.16, 0.12 or width of the 3rd rib 3x), mediastinal mass, PTX, pneumomediastinum
- Tracheo-bronchoscopy
• Mucosa, culture, cytology, biopsy, foreign body removal - Blood tests
• Rarely useful, systemic or allergic disease - Faeces flotation
• Lungworm infection
Non-infectious tracheitis
Non-infectious or infectious; primary or secondary
- Causes
• Prolonged barking, collapsing trachea, chronic cardiac disease, allergic lower airway disease - Tests
• Firm palpation of the thoracic inlet → typical tracheal cough; tonsils; cardiac murmur +/-, lung sounds +/-, X-ray (Ø?), atopy screening? - Treatment
• Antitussives (codeine, butorphanol, dextromethorphan)
• Broncho-dilating drugs (theophylline/aminophylline, terbutaline)
• Prednisone
• Nebulization (6 times daily)
• Treatment of underlying disease
Infectious tracheobronchitis
Causes
• Kennel cough complex (CAV-2, CPI, Bordetella bronchiseptica)
• Distemper
• Others (reovirus, CHV, Mycoplasma spp.)
- History
• Highly contagious!
➢ Pension for dogs, hospital, kennel, dog parks
Clinical signs
• Acute onset of dry, hacking, paroxysmal cough, often followed by retching and gagging, often productive (white froth), in generally healthy dogs (systemically well)
• Cough can be stimulated by pinching the trachea
• Can lead to systemic illness if Bordetella pneumonia occurs
- Diagnosis
• Combination of history and clinical signs
• If systemically ill, older, heart disease then radiographs +/- bronchoalveolar lavage - Treatment
• Isolation of infected animals
• Antitussives (codeine, tramadol)
➢ Avoid cough suppressants if ill and suspect bronchopneumonia
• Antibiotics (BAL?, systemic illness; cephalosporins, amox+clav, doxycycline → BUT not proven to alter outcome)
• Bronchodilators
Tracheal collapse - aetiology
Middle-aged to aged toy and miniature breeds! (Chihuahua, Yorkshire terrier, toy poodles, Shi Tzu, Lhasa Apso, Pomeranian)
• Acquired > congenital
• DV > LL
• Can affect different areas of the trachea, extrathoracic, thoracic inlet, intrathoracic regions and also the bronchi
➢ Extra-thoracic regions = inspiratory obstructive dyspnoea
➢ Intra-thoracic region and bronchi = expiratory obstructive dyspnoea
• Cervical > intrathoracic
- Aetiology: caused by a weakening of the tracheal cartilages (failure of chondrogenesis, degeneration? – suspected to be caused by a reduction in the glycosaminoglycan content of the cartilage rings) → loss of support of the dorsal tracheal membrane which then collapses into the lumen
• Stage I – IV
Associated problems with tracheal collapse
Chronic coughing (chronic airway or pulmonary parenchymal disease, chronic cardiac disorders) obesity, mediastinal fat, mass
History and clinical signs of tracheal collapse
Long history of coughing, from mild, intermittent to paroxysmal “goose-honk” cough, elicited by palpation, eating, drinking, excitement, cyanosis +/-, auscultation (inspiratory noises!), palpation!
Diagnosis of tracheal collapse
Fluoroscopy
➢ Best as can visualise collapse
• Radiography (respiratory phase!)
➢ 3 views both inspiratory and expiratory views
➢ Rule out coagulopathy as it can also cause the appearance of a collapsed dorsal tracheal membrane
• Bronchoscopy (stage I – IV)
➢ +/- bronchoalveolar lavage if concurrent pulmonary disease
Treatment of tracheal collapse
Respiratory emergency patient → acute stabilization!
➢ Sedation (butorphanol – anxiolytic and antitussive effects, acepromazine), oxygen therapy, glucocorticoids, (dexamethasone first, then long-term prednisolone) intubation?, cooling
Medical management of tracheal collapse
Antitussives (butorphanol, hydrocodone – MiniVet Guide: codeine or tramadol)
➢ Anti-inflammatory inhalers: Prednisone (in tracheal oedema, tracheitis)
➢ Bronchodilators (according to lecture YES – according to MiniVet Guide: maybe worth a try - but it is actually not a broncho-constrictive disease)
➢ Management of exacerbating factors
o Treatment of concurrent disease, e.g. heart disease, pneumonia
o Weight reduction
o Reduce allergen exposure
Surgical management of tracheal collapse
➢ Last resort
➢ Intraluminal stents (failure to function well, migration)
➢ Extraluminal prostheses (laryngeal paralysis!)
➢ Plication
Tracheal hypoplasia everything
Congenital problem diagnosed in young dogs!
• 2 days to 12 years, median 5 months
• Bulldogs, Boston Terrier
- Dyspnoea, productive coughing, fever if bronchopneumonia
- Auscultation, sensitive trachea, radiography (Ø trachea / thoracic inlet < 0.2 dolio-cephalic, < 0.16 brachycephalic, 0.12 bulldogs), leucocytosis
- Tracheal oedema in tracheitis may mimic hypoplasia on the radiograph → X-ray in asymptomatic patients!
- Prognosis
• Degree of hypoplasia, concurrent upper respiratory diseases, congenital cardiac disorders!
- Treatment
• Brachycephalic airway syndrome (nose, elongated soft palate, laryngeal collapse)
• Bronchopneumonia
- Tracheal hypoplasia: there are no known surgical corrective procedures
- Prevention
• Advisable to discourage the breeding of these animals
Tracheal parasites
Rare, but worldwide disease
- Oslerus osleri (Filaroides osleri) = lungworm
• Chronic dyspnoea, coughing (dry), inspiratory wheezing sounds
• Kennel-related problem?
• Worms at the carina (bronchoscopy, feces), 1 – 5 mm nodules
fenbendazole for 10-14 days
Other diseases of the trachea
Trauma • Emphysema • PTX • Pneumomediastinum - Obstructive tracheal masses • Intraluminal lesions ➢ Neoplasia ➢ Foreign body • Extraluminal compression - Segmental tracheal stenosis • Congenital • Acquired
