Marli's Chi's - AKC Longcoat Chihuahuas
Tracheal collapse is a condition in which the trachea partially collapses as a dog breathes, leading to tracheal irritation, coughing and sometimes secondary changes in the lungs or upper airways. It is most common in toy breed dogs but can occur in larger breeds at times. It is likely that this condition is partially the result of breeding for small size. It is reported to be most common in Yorkshire terriers, poodles, Chihuahuas, pugs and Pomeranians have been reported to be the breeds most commonly affected by this condition (Slatter's Textbook of Small Animal Surgery) but it is reasonably common in all the toy breeds and several other smaller dog breeds.
The trachea is the airway from the larynx to the main bronchi in the lungs.
It looks a lot like a "Shop-Vac" vacuum cleaner hose --- lots of
stiff rings with flexible tissue connecting them. The rings are actually more
like the letter C with the free ends slightly overlapping and are composed of
stiff cartilage when properly formed. For some reason, the rings are not stiff
enough in some dogs and they can't hold the trachea open against the negative
air pressure created during respiration. The portion of the trachea that is not
stiff is sucked into the airway, partially obstructing it and leading to
irritation and coughing. This happens on inspiration when the portion of the
trachea affected is in the neck region and on expiration if the trachea inside
the chest itself is the problem. The irritation is self perpetuating, since
coughing and increased respiratory efforts lead to further irritation and
worsening of clinical signs. Eventually, damage can occur to the lungs, larynx
or even upper airways (nasal passages and soft palate regions). Part of the
problem is anatomical, but not all dogs with identifiable tracheal collapse show
significant clinical signs, so other factors must be partially responsible.
Obesity, irritants, allergies, obesity, concurrent heart failure, obesity,
bacteria, viruses and obesity can all contribute to the problem, as well. If a
pet owner smokes, this is another good reason to quit doing so. Smoking does
seem to be a factor in
initiating and prolonging symptoms of tracheal collapse. The tracheal lining is ciliated and the cilia move in unison, sweeping a layer of mucous, antibodies and other protective substances constantly towards the larynx. This helps to keep foreign material out of the lungs. Chronic irritation of these tissues may make the overall disease in dogs with tracheal collapse much worse.
Cats can have problems with tracheal collapse but it occurs much less frequently in cats than it does in dogs.
The symptoms of tracheal collapse are coughing, difficulty breathing and
tiring easily. The cough is usually very harsh, often sounding like a
"goose honk". When this condition first occurs many dog owners
truly believe that there must be something caught in their dog's airway due to
the severity of the cough. In many cases, dogs with tracheal collapse will also
have other airway problems such as stenotic (too narrow) nostrils, soft palate
disorders and laryngeal damage. Secondary lung changes can occur with this
condition that eventually lead to chronic obstructive pulmonary disorders. If
the tracheal collapse is occurring inside the chest the increase in pressure on
the circulation can lead to heart enlargement or contribute to heart failure. It
is very important to evaluate patients suspected of having tracheal collapse
very carefully to find problems that may be contributing to the collapse and
problems that may be resulting from the collapse. Most other problems found
should be corrected if possible since almost all of them respond to treatment
better than the collapsing trachea itself. In some cases control of initiating
factors such as stenotic nares (nostrils) may even alleviate the symptoms of
collapsing trachea, at least for a while.
A honking cough in a small breed dog should make a pet owner or veterinarian highly suspicious of tracheal collapse. The average age of onset is somewhere between six and eight years of age but it can occur at a much younger age or wait to show up until much later in life. It may be possible to feel the collapse of the trachea with the fingers on exam. In some cases the narrowing of the trachea can be caught on an X-ray or by ultrasound exam. The best and most definitive way to diagnose tracheal collapse is with an endoscope, though. As the veterinarian looks into the trachea it is possible to see the collapse and to make an assessment of where it is occurring. In most cases the diagnosis is probably made by relying on the history and perhaps X-rays. This is a pretty reliable way to make the diagnosis since the history (including dog breed) and clinical signs are very suggestive of this problem. However, if endoscopy were available at most veterinary hospitals I'm sure it would be the most common way to confirm the diagnosis. In any case in which response to treatment is questionable or when there are complicating factors such as concurrent heart disease it would be a good idea to ask your vet about referral to a specialist or veterinary hospital where endoscopic diagnosis is possible.
There are medical treatments for collapsing trachea as well as surgical treatments. The consensus of opinion seems to be that collapsing tracheal problems are best treated medically until it becomes obvious that medical treatment alone is not going to work. Medical treatment is aimed at controlling the cough, dilating the airways if possible and controlling the secondary inflammation of the tracheal tissues. Bronchodilators such as theophylline, antihistamines such as terbutaline or hydroxyzine and combination products such as Marax (Rx), which is aminophylline, ephedrine and hydroxyzine are used to try to provide a more patent airway. Corticosteriods such as prednisone are used to control inflammation. Cough suppressants such as dextromethorphan, butorphenol (Torbutrol Rx), and hydrocodone (Hycodan and other, Rx) are the most useful medications in our clinic. Controlling the coughing often will allow resolution of the other problems associated with this condition and slow the self-destructive cycle that occurs with tracheal collapse. It is likely that cough suppressants are under-dosed more frequently than over-dosed in dogs with tracheal collapse. Many pet owners notice the most improvement with prednisone but under-dosing of cough suppressants may be partially responsible for this perception. Estimates of success with medical treatment vary but one study (R. A. S. White and J. M. Williams in the April 1994 Journal of Small Animal Practice) reported a 71% success rate with medical treatment. If medical treatment is unsuccessful after the initial attempts or if it becomes less successful over time, surgery is an option. The reported success rate of surgical treatment also varies widely in the literature but it appears that surgery is successful approximately 70% of the time as well. With surgery there is some chance, perhaps as high as 1 in 5, of the dog being worse post-surgically, though. Laryngeal paralysis may occur due to damage to the nerves during placement of tracheal ring supports and it may be necessary to do a permanent tracheostomy if this occurs. In a recent report in the AVMA Journal, Drs. Bubjack, Boothe and Hobson reported that this was necessary in 10 out of 90 patients treated surgically. They felt that the best surgical results were obtained in dogs with early onset of tracheal collapse when surgery was performed prior to six years of age. It seems to be the consensus among surgeons that tracheal collapse occurring in the neck region is more likely to respond to surgical correction than tracheal collapse occurring inside the chest (thorax). In summary, medical treatment appears to be the best approach if the symptoms can be controlled with prednisone, cough suppressants, antihistamines and bronchodilators, or by any combination of the above medications. If there is a poor initial response to medical therapy or if the response deteriorates over time, then surgical treatment should definitely be considered, especially if the collapse seems to be occurring in the cervical (neck) region of the trachea. Treat any possible initiating causes found on careful exam of the pet and treat any secondary problems that occur after the diagnosis of collapsing trachea. Dogs with this problem should probably be examined at least twice a year to allow early detection of any secondary problems that do occur. Weight loss is often enormously beneficial but can be difficult to achieve in a pet that has limited ability to exercise. While it may be very difficult to enforce a strict diet, the end result could be a much healthier and happier dog.
The best reference for a more detailed understanding of tracheal anatomy, function and disease is probably Slatter's Textbook of Small Animal Surgery, 2nd edition. This is a two volume set and it has detailed explanations of normal anatomy and normal function and how they are changed in disease states for many problems that will respond to surgical correction.
Paroxysmal Respiration, or "Reverse Sneezing", and Collapsing Trachea Syndrome
I am certain that the condition referred to as inspiratory paroxysmal respiration, or reverse sneezing, and collapsing trachea syndrome are totally different conditions.
However, I think that the symptoms of these conditions are very similar in some cases, though. Especially in dogs with severe coughing episodes associated with the tracheal collapse, which can look a lot like the extreme inspiratory effort that is typical of reverse sneezing.
There are other reasons for confusion between these conditions. They both occur most commonly in small breed dogs and it is likely that there are a number of dogs who have both conditions. Tracheal collapse can be aggravated by any other condition affecting the respiratory tract, making it possible for a dog with reverse sneezing to develop tracheal collapse symptoms over time.
I think that there are probably a number of causes of reverse sneezing and that many cases occur for no discernible reason. According to the "Textbook of Veterinary Internal Medicine" by Ettinger and Feldman, swallowing stops attacks of reverse sneezing. This source says that reverse sneezing may be controlled by massaging the pharyngeal area or briefly closing the dog's nostrils. Several of my clients have mentioned that their dogs respond to rubbing of the upper neck region, so this advice may be useful. Reverse sneezing is a problem of the pharyngeal region.
Tracheal collapse is a problem that occurs because of improper formation of the tracheal rings. Weakness in the tracheal rings leads to a condition in which the trachea collapses, either during inspiration or expiration, depending on the location of the problem in the trachea. This is highly irritating to the dog and coughing results.
Reverse sneezing tends to start at an early age and to be a persistent problem. Tracheal collapse may cause some symptoms at an early age but in most patients there is a gradual increase in coughing over time and it may reach a point in which there are coughing episodes that last for several minutes and do resemble reverse sneezing. Severe tracheal collapse symptoms are more common in older dogs.
Mike Richards, DVM
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