The stent size should be determined by considering two main factors:

a. Tracheal internal diameter: this is assessed on dynamic radiographs, ensuring that the stent selected is slightly larger in diameter than the trachea to ensure a proper fit.

b. Length of the affected segment: it is crucial to choose a stent that covers the necessary length of the collapse or stenosis, but without interfering with adjacent structures such as the larynx or main bronchi.

Suggested approximate sizes that other colleagues usually ask for are:

Yorkie/Pomeranian (2-4 kg): Stents with internal diameters of 6-8 mm and lengths between 2-4 cm.

Poodle or similar breeds (~6 kg): Stents with internal diameters of 8-10 mm and lengths of 4-6 cm.

However, the final size is always at the discretion of the veterinarian, depending on the case and the particularities of the patient.

Yes, the internal diameter of the trachea is used as the primary reference for determining the stent diameter. This value should be taken at the widest point and at the narrowest area of the affected trachea to ensure a proper fit.

The length should exceed 5mm at the ends of the stenosis, so that the ends of the stent ‘float’ in the area, avoiding excessive rubbing of the stent edges against the healthy part of the trachea (the stents have biseal edges to minimise this anyway).

For determining the measure, a bronchoscope or tracheoscope would be fine, and is the common instrument the physicians have in their human interventional facilities. But anything that helps you for comparison is good too.

• For example: a forceps or a catheter.

• The maneuver to determine the length of the stent would be:

1. putting the extreme of the object in the distal end of the injury,

2. mark the object,

3. move the object to the proximal end,

4. mark the object again,

5. measure the distance between the 2 marks,

6. pick a stent that exceeds that length in about 10mm (5mm before the injury and 5 mm after the injury).

To determine the diameter of a bronchoscope or tracheoscope are very good too, but any object that you know the diameter and is approximate to the animal larynx or trachea diameter is also good. Even a forceps, that you can open inside the injury, remove without changing and then measure the size of that opening.