Hypoplastic trachea is a genetic disease of dogs associated with brachycephalic syndrome and characterized by malformation of the tracheal cartilage rings that leads to narrowing of the airway.
Predominantly affected breeds included English Bulldog, Pug and Boston Terrier and the condition usually involves other upper airways diseases such as stenotic nares, elongated soft palate and everted laryngeal saccules.
Clinical signs may vary depending on the degree of tracheal narrowing and affected dogs usually present with upper airways noises such as stridor or stertor, exacerbated while eating or drinking. Aspiration pneumonia can develop in some dogs. The condition appears to be aggravated by obesity.
Diagnosis is usually established on clinical history and supportive radiographic evidence of narrowing of tracheal diameter. This condition needs to be differentiated from tracheal collapse.
Although there is no specific treatment indicated for this condition, tracheal hypoplasia in some brachycephalic dogs can partially or completely resolve with growth to mature body size.
By Dr. Becker
Tracheal collapse is a chronic, progressive disease involving the windpipe, or trachea.
The trachea is somewhat like a vacuum cleaner hose that contains small rings, in this case cartilage that keeps the airways open.
The rings are C-shaped, with the open part of the "C" facing upward.
Running along the top opening of the C-rings is a band of tissue called the dorsal membrane.
How the Trachea Collapses
In certain dogs, the rings of cartilage are either not formed correctly at birth, or they weaken and begin to change from a C-shape to more of a U-shape.
As the dorsal membrane stretches, the cartilage rings get progressively flatter until eventually the trachea just collapses, leaving the dog trying to pull air through what is essentially a closed straw.
Tracheal collapse can be congenital, which means it's present from birth, or it can be acquired. When the condition is congenital, it appears to be a result of a deficiency in certain components of the cartilage rings, like calcium, chondroitin, glycoproteins and glycosaminoglycans.
Acquired tracheal collapse is often caused by chronic respiratory disease, Cushing's disease and heart disease. Collapse of the trachea in the neck occurs when the dog breathes in. Collapse of the trachea in the chest occurs when the dog breathes out. The collapse can involve the bronchi that feed air to the lungs, which results in serious airway obstruction in the dog.
Tracheal collapse is most common in small breed dogs like the Chihuahua, Lhasa apso, Maltese, Pomeranian, pug, Shih Tzu, toy poodle and the Yorkie.
One of the first signs of tracheal collapse can be a sudden attack of dry coughing that sounds a little bit like a goose honk. It progresses from the goose honk sound to a more consistent cough and often occurs when there's pressure placed on the dog's trachea. This can happen when the dog is picked up or if the collar is pulled.
As the disease progresses, the dog can develop exercise intolerance, obvious respiratory distress, and gagging while eating or drinking.
Some dogs with tracheal collapse can turn blue when they are excited or stressed. Certainly, secondary heart disease can result from the consistent straining to breathe.
Some dogs have both laryngeal paralysis and tracheal collapse. These dogs usually make a wheezing sound when they breathe in.
Diagnosis of Tracheal Collapse
Tracheal collapse can sometimes be seen on a regular X-ray as a narrowing of the tracheal lumen, or opening.
Fluoroscopy, which is a moving X-ray, allows the vet to visualize the dog's trachea as he breathes in and out.
An endoscopy allows a view of the inside of trachea with a tiny camera. It really provides the best way of viewing the inside of the airway. During this time, the veterinarian can also take samples of the trachea for culture and sensitivity tests or additional analysis.
Sometimes an echocardiogram is recommended to evaluate heart function.
Any disease of the upper or lower airway can be mistaken for tracheal collapse, including a foreign object in the airway, laryngeal paralysis, an elongated soft palate, infection of the trachea, lungs, or heart failure, as well as tumors or polyps. So it's pretty important that you get a definitive diagnosis and not just a guess.
Conventional medical management of mild to moderate cases of tracheal collapse involve the use of cough suppressants, antispasmodics, bronchodilators, and sedatives to help reduce coughing spasms and the associated anxiety.
It's important to break the coughing cycle, because coughing irritates the airway and leads to more coughing.
If infection is present, of course, that has to be addressed as well. And certainly if the dog is overweight, it's really important that he lose weight.
I also recommend you evaluate your dog's environment. It should be smoke-free and free of other environmental pollutants.
Any dog with a collapsing trachea should be walked using a harness only. I absolutely do not recommend anything around the neck, as reducing all pressure at the throat is really important for these dogs.
Medical management works for about 70 percent of dogs with the mild form of this condition. Holistic veterinarians usually recommend cartilage builders to help maintain the integrity of the tracheal cartilage.
These supplements can include glucosamine, chondroitin, MSM, eggshell membrane, and CMO, which is also called cetyl myristoleate. Sometimes, chiropractic and acupuncture have also been demonstrated to reduce the intensity of the duration of coughing episodes.
In more severe cases or for dogs who don't respond to medical management, sometimes surgery is recommended. If the collapse is happening in the neck or the thoracic inlet, plastic rings are placed surgically around the inside of the trachea.
If the collapse is deeper in the chest, often a stent is placed in the trachea. A stent is basically like a tiny spring that holds the trachea open.
Repair of a tracheal collapse is a very specialized surgical procedure. Don't let your veterinarian tell you that it's no big thing. These particular procedures have significant potential for complications. They should only be performed by a veterinary surgeon that has really extensive knowledge and a well-equipped hospital with a staff able to help your dog recover from this significant procedure in an appropriate manner.