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TRACHEAL COLLAPSE IN DOGS

Colapso-traqueal-veternaria

Tracheal collapse is one of the most common respiratory diseases in dogs. In this post we are going to review through a series of questions the main causes, symptomatology and diagnosis of tracheal collapse in dogs.

What is the cause of tracheal collapse in dogs?

Tracheal collapse in dogs is a multifactorial disease. It is initiated by a weakness (tracheomalacia) in the tracheal cartilage, which occurs in some breeds of dogs, due to a reduction of glycosaminoglycans and chondroitin sulfate. Over time, triggering or perpetuating factors are added to this initial pathology, such as obesity, cardiomegaly, respiratory infections or inflammations, or breathing irritants such as tobacco smoke.

Which patients are usually affected?

Tracheal collapse in dogs most commonly affects patients of small breeds such as the Yorkshire terrier, pomeranian, bichon, pug, Chihuahua or poodle.The clinical signs usually appear in adult or geriatric patients, although it can also be observed in young animals, especially in those dogs, as is frequently the case in the Yorkshire terrier, with tracheal malformations.

What are the most common clinical signs?

There are three main clinical signs:

  1. Cough, which is often dry and with similarity to a goose squawk.
  2. Noisy breathing, with a respiratory rattle, often marked.
  3. Dyspnea, shortness of breath with a prolonged inspiratory phase.

What is the best diagnostic method for tracheal collapse in dogs?

The diagnosis can be made by radiography,observing a characteristic narrowing of the trachea (Figure 1). It should be noted, however, that being a dynamic process it can give false negatives in up to 50% of cases. The extrathoracic trachea collapses on inspiration, and the intrathoracic trachea collapses on expiration, so it is important to acquire tracheal views on inspiration and expiration during radiographic examination.

Colpaso traqueal en perros
Lateral radiograph of a Pomeranian dog with severe tracheal collapse (green arrows).

We aim Respiratory fluoroscopy (Figure 2) allows visualization of the trachea during normal breathing and intrathoracic pressures (unaffected by anesthesia) and also allows evaluation of the trachea during provoked coughing episodes. It is therefore an ideal method for assessing the severity and extent of tracheal collapse and allows the diagnosis of patients who may be elusive to diagnosis by other methods.

fluoroscopia en un Yorkshire terrier con traqueomalacia severa
Fig 2. Image captured from fluoroscopy in a Yorkshire terrier with severe tracheomalacia with evidence of severe tracheal collapse (red arrows) and tracheal fold (yellow arrow). The blue arrow indicates the normal appearance of the trachea before folding and collapse.

We aim endoscopy is complementary to fluoroscopy and allows evaluation not only of the trachea and the presence of tracheal collapse and its severity (Figure 3), but also the upper airways, bronchi and lower airways and sampling for concurrent infection or inflammation.

Tracheal collapse can also be detected with TAC which, together with endoscopy and fluoroscopy, can be part of a complete respiratory workup. If these are under anesthesia, it is important to introduce the endotracheal tube as little as possible into the trachea and to take into account the limitations in assessing the severity and extent of disease under non-physiologic respiratory and intrathoracic pressure conditions.

graduación de la severidad del colapso traqueal. 
Figure 3a. Graph indicating the grading of the severity of tracheal collapse.
Colapso traqueal en perros
Figure 3a. Grade III tracheal collapse in a Yorkshire terrier observed during tracheoscopy.