Therapeutics

Treatment is aimed at relieving immediate respiratory distress, managing acute and per­sistent coughing, and addressing underlying co-existing or exacerbating factors (e.g., con­current congestive heart failure or laryngeal paralysis).

Supportive Measures

• Avoiding collars

• Weight loss

• Environmental temperature control and humidification

• Avoiding airway irritants

• Minimizing anxiety

• Controlled exercise - provided it is does not cause coughing or respiratory distress

• Management of concurrent diseases.

Medical Treatments

• Oxygen therapy

• Anxiolytics (opioids, acepromazine, trazo­done, or others)

• Antitussives

î Opioids (butorphanol, hydrocodone, and others)

î Nebulized lignocaine and furosemide (reported in human medicine but very little literature in veterinary medicine)

• Corticosteroids (Parental, oral, and inhaled)

• Bronchodilators - no proven benefits, but have traditionally been used and are rec­ommended in texts. A therapeutic trial can be attempted.

• Antibiotics. Tracheal collapse is a non- infectious disorder thus no need for antibi­otics unless bacterial infections complicate the case.

• Experimental treatment

î Stanozolol (Adamama-Moraitou et al. 2011)

• Unproved/ineffective/low evidence based therapies (although often used in practice) î Doxycycline (unless susceptible infec­tious airway disease is present)

î Polysulfated glycosaminoglycan

î Neurokinin-1 receptor antagonist - maropitant (Grobman et al. 2015a; Grobman et al. 2015b)

Surgical Options (Sun et al. 2008; Chisnell and Pardo 2015)

• External tracheal ring prostheses

• Intraluminal stent.

• Procedures largely replaced by the above î Dorsal tracheal ligament plication

î Tracheal ring chondrotomy î Prosthetic polypropylene mesh reconstruction

The Asymptomatic Patient

When tracheal collapse is identified inciden­tally, or as asymptomatic disease (those with only the occasional spontaneous cough and without respiratory compromise) treatment is usually not required.

The Coughing Patient Without

Respiratory Compromise

Medical management as an outpatient is usually sufficient. The diagnostic and thera­peutic approach is aimed at diagnosing collapsing trachea; identifying associated disorders; and addressing and applying supportive measures, including antitussives. Glucocorticoids, preferably inhaled formula­tions, remain central to controlling secondary airway inflammation and coughing, espe­cially with the evidence that bronchomalacia is associated with chronic inflammatory airway disease. Corticosteroids are titrated to

the lowest effective dose. Initial clinical improvement with medical therapy can be expected in over two-thirds of patients (White and Williams 1994).

The (Coughing or Noncoughing) Patient with Respiratory Compromise

Generally, these patients have been previ­ously diagnosed and are already on treat­ment. Medical and supportive management has been applied, but is no longer effective. Respiratory distress may be episodic, resolving spontaneously, or severe and persistent with the patient presenting as a respiratory emergency, severely compro­mised. Immediate treatment goals are aimed at decreasing the breathing rate and effort by supportive measures, such as cooling, and medical treatment. These include oxygen therapy, decreasing anxiety (i.e., decreasing hyperventilation), antitus- sive therapy (coughing exacerbates airway collapse), short-acting glucocorticoids, bronchodilators when bronchoconstriction is a comorbid problem, and providing ven­tilator support when in extremis by means of intubation with positive pressure venti­lation (PPV). It is important to note that supplying oxygen by facemask or oxygen chambers may have limited success in patients with severe tracheal collapse as these animals are unable to ventilate and move oxygen enriched air into the lungs.

Patients that require PPV will mostly require a surgical solution. If PPV is not available, then endotracheal intubation will be necessary. Placing an oxygen delivering feeding tube through an endotracheal tube to the level of the carina will bypass tracheal (but not bronchial) collapse. Unless a stent is readily available for placement or the precipi­tating factor that induced ventilation failure can be rapidly corrected (e.g., severe panting due to heat stroke), intubation and ventila­tion will not aid long-term survival and euthanasia should be considered. While PPV is not ideal; it may provide a sufficient bridge in those dogs that have an acute reversible exacerbating factor.

In patients with episodic airway compro­mise, managing the whole airway is crucial. Diagnosing and correcting problems that increase airway resistance (such a chronic rhinitis, narrow nares, elongated soft palate, laryngeal collapse, everted laryngeal ventri­cles, and chronic lower airway inflammatory disease) will alleviate airway collapse by decreasing the effort required to breathe, without directly affecting the underlying tra­cheal collapse, and hopefully delaying the need for surgical intervention.

When respiratory compromise progresses or becomes refractory, surgical options remain the only means of providing relief in cases of airway collapse (Sun et al. 2008). Failure to administer medication is not a valid reason to seek surgical solutions, as most animals will require additional medical management afterwards.