Collapsing trachea

If you have a small dog that coughs every time it gets excited or pulls on its lead it may be suffering from tracheal collapse. Tracheal collapse results in narrowing of the airway and, if left untreated, can progress over time causing severe consequences for your pet. If your dog develops a cough that does not get better after 2 weeks you should make an appointment to see your vet.

The trachea (also known as the wind pipe) is a tube that runs from the throat down into the chest where it branches to form the major airways in the lungs. The normal trachea is a soft tube that is held open by numerous rigid rings of cartilage. In some dogs the tracheal rings gradually weaken over time so that they are not sufficiently rigid to hold the tube open and the walls collapse inwards narrowing the airway.

Tracheal collapse is mostly seen in toy breeds (e.g. Yorkshire terriers, Pomeranians and Poodles) but has also been reported in some larger dogs. In many toy breeds of dog there is a tendency to have softer tracheal rings which makes development of tracheal collapse more likely. Most dogs are middle-aged (around 7 years of age) when they develop signs but occasionally a congenital form is present from birth and can cause clinical signs in animals as young as 4 months of age. Animals with tracheal collapse that are overweight are more likely to show signs of coughing.

Dogs with tracheal collapse initially develop a classical cough which may persist for months or years before owners seek investigation. The cough associated with tracheal collapse is described as ‘goose honking’ as it supposedly sounds like the noise made by geese. The cough often comes on when the dog is excited or has been pulling on the lead and once an affected dog has started to cough they may have a prolonged bout during which they cannot stop coughing. Affected dogs may faint during a coughing spell. Severely affected animals may be unable to exercise normally and may even turn blue when they are excited or stressed.

Your vet will probably suspect a diagnosis of tracheal collapse based on the history and by listening to your dog cough. However, there are other diseases that can cause chronic coughing and it is important to make sure these are not present before a final diagnosis is made. Investigation of the condition involves X-rays of the trachea and the lungs and your vet may want to pass an endoscope (a small tube with a camera on the end) through the trachea to see if collapse is occurring.

In many cases it is possible to control the condition initially with simple changes to management. Weight loss in overweight animals will always help and, since coughing is exacerbated by exercise or pulling on a lead, exercise reduction and fitting a harness instead of a collar should help reduce the cough. Any respiratory diseases should be treated and environmental triggers such as pollens and cigarette smoke should be avoided.

Medical treatment may also be required to control the signs. Steroids can be used to reduce the irritation in the airways; sometimes these are given using an inhaler (similar to that used by asthmatics) as this reduces the side effects of steroids on other parts of the body.

Other drugs that may help to reduce coughing are cough suppressants, airway dilators and drugs to dry up secretions in the airways. Your pet may also need courses of antibiotics from time to time to reduce bacterial infections in the airways. Most animals cope reasonably well on medical management for years after diagnosis.

In some cases medical treatment alone is not sufficient and if this is the case it may be wise to talk to your vet about possibilities for surgery. The aim of surgery is to help improve the structure of the trachea to limit collapse as much as possible; this helps to improve airflow, but will not completely resolve other signs such as coughing.

An operation is available to place artificial rings around the trachea to hold it open; this technique can work very well, however this operation is very challenging as often the collapsing portion of the trachea lies within the chest so the procedure is not without risks. More recently techniques to provide internal support to the trachea using stents have had promising results. A tracheal stent is a flexible metallic tube, usually made of a special metal called nitinol (a nickel titanium alloy), which is designed to stay within the lumen of the trachea and hold it open.

Stents are placed under general anesthesia using fluoroscopy (real time movie like X-rays) to assess positioning. The stent needs to be carefully measured so that it is the correct size, but once in position, they are very well tolerated to the extent that the tracheal membrane will grow over the inert surface of the stent and they stay in position lifelong. Stent placement is much less invasive compared to open surgery with very encouraging long term results.

Surgical treatments of tracheal collapse should be performed by a specialised veterinarian with experience and specialist training in the technique, so your vet may make a referral to a specialist centre for the procedure. It is important to remember that the aim of surgery is to help improve airflow and that longer term medication will be needed after both artificial ring and stent placement to limit coughing and prevent inflammation.