Auscultation of an end-respiratory 'snap' heard during spontaneous or induced cough.
Often induced by excitement.
Exacerbated when dog pulling on lead.
Has classical goose honking sound. The end-respiratory snap is a sound heard best with the stethoscope placed over the mid-thorax as the patient coughs. The abrupt cessation of the cough (culminating in a so-called 'snap'), is quite distinct and denotes the sides of the airways actually impacting each other.
Exercise intolerance.
Syncopal episodes associated with paroxysmal coughing episodes.
Clinical signs
Palpation or compression of the trachea paroxysmal coughing.
Flattened trachea may be palpated if extrathoracic.
Obesity may exacerbate clinical signs.
Increased respiratory noise on auscultation of concurrent pulmonary pathology, eg chronic bronchitis.
Diagnostic investigation
Tracheoscopy
Tracheal walls collapse on expiration.
Widened and thickened dorsal ligament which can be inverted into the lumen by external pressure.
Deformed cartilaginous rings, (congenital). Examine animal for laryngeal collapse or paralysis at same time.
Radiography
The lateral projection of the thoracic cavity, to include the thoracic inlet, should be employed if it can be performed without distressing the dog.
Radiographs of cervical region and thorax , are indicated.
Obvious narrowing of the cervical trachea, especially at the thoracic inlet and in some cases in the thoracic trachea. Do not misinterpret overlying soft tissue density of esophagus as tracheal narrowing.
Can take inspiratory and expiratory films to show dynamic collapse. Dorsiflexion or ventriflexion of the neck may cause apparent tracheal narrowing.
Thoracic radiographs , are indicated for identification of any underlying pulmonary pathology.
Other
Fluoroscopy.
On inspiration the cervical trachea will collapse while the thoracic segment dilates, and vice versa on expiration.
Confirmation of diagnosis Discriminatory diagnostic features
History.
Signs.
Radiography.
Definitive diagnostic features
Endoscopy.
Fluoroscopy.
Gross autopsy findings
Examine entire respiratory tract to rule out other causes of dyspnea.
Inspect external nares, open internal nares, inspect larynx and full length of trachea.
Main finding in congenital tracheal collapse is dorsoventral flattening of trachea, with broad dorsal ligament.
Froth in the trachea is a common agonal change, but can be seen in partially obstructed tracheas.
Open entire length of trachea to check for areas of mucosal inflammation.
Open trachea and bronchi to rule out other causes of dyspnea.
Save trachea (multiple cross sections), plus lung for histology.
Histopathology findings
May have focal areas of mucosal erosion or even metaplasia due to chronic irritation.
Cystic mucus glands and inflammation of mucosa and submucosa may be present.
Sedatives may be used to prevent excessive excitement on stressful occasions.
Conservative treatment
Many cases may be managed conservatively for long periods by medication:
Antisecretory drugs.
Steroid therapy, eg Prednisolone (0.5 mg/kg PO BID for 3-5 days as required). (Care if obese - weight reduction more important.)
Antitussives, eg butorphanol (0.05-0.1 mg/kg PO SID-TID), or hydrocodeine (0.22 mg/kg PO SID). Antitussives should only be used to control excessive or debilitating coughing
Administration of antimicrobial therapy is indicated in some patients, particularly older dogs with acquired tracheal collapse.
Bacteria in the distal airways contribute significantly to the pathogenesis of small airway disease, obstruction, and aerodynamic airway collapse.
Antibiotic therapy alone may have more impact on controlling the cough of affected animals than antitussives.
Drugs used include:
Amoxycillin-clavulanate , (12.5-25 mg/kg PO BID for 3-4 weeks or as needed to control cough).
Doxycycline , (5 mg/kg PO BID for 3-4 weeks or as needed to control cough).
Enrofloxacin , (5 mg/kg PO SID for 3-4 weeks or as needed to control cough).
Standard treatment
Majority of cases can be treated medically.
Surgery
Because of the high complication rates associated with surgical intervention, the procedures listed below should be performed only as a last resort and conducted by surgeons with experience in the procedure:
Interluminal prosthetic supports.
Tracheal ring section.
Dorsal membrane plication - high risk, (probably best referred).
External prosthetic support . Surgical management should only be undertaken if all other airway obstructing problems can be dealt with adequately. Round the clock postoperative care is essential for at least 3-5 days.
Buback J L, Boothe H W & Gobson H P (1996) Surgical treatment of tracheal collapse in dogs - 90 cases (1983-1993).JAVMA208 , 380 PubMed.
White R A S & Williams J M (1994) Tracheal collapse in the dog - is there a role for surgery? A survey of 100 cases.JSAP35 , 191.
Other sources of information
Herrtage M E & White R A S (2000) Management of tracheal collapse. In: Kirk's Current Veterinary therapy XIII. Ed: J Bonagura. Philadelphia: W B Saunders, pp 796-801.
Vetstream contributor(s)
Dr Richard Ford DVM DipACVIM , College of Veterinary Medicine, North Carolina State University, 700 Hillsborough Street, Raleigh, NC 27606, USA.
respiratory obstruction on expiration.
The end-respiratory snap is a sound heard best with the stethoscope placed over the mid-thorax as the patient coughs. The abrupt cessation of the cough (culminating in a so-called 'snap'), is quite distinct and denotes the sides of the airways actually impacting each other.
Do not misinterpret overlying soft tissue density of esophagus as tracheal narrowing.