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The trachea is the passageway through which
air enters the lungs. It starts at the larynx (voice box) and goes down
the neck into the chest cavity (thorax) where it splits into two main
branches (bronchi) to join the two lungs. In the dog, the trachea is
composed of a cartilage ring that is about 275 degrees of a circle with
a membrane completing the other 85 degrees on the top. In humans, the
cartilage forms a complete circle around the trachea and keeps it from
collapsing.
When a pet breathes in, s/he creates negative pressure in the chest by
expanding the ribs and the diaphram. This action sucks air into the
lungs. The negative pressure also pulls on the membranous portion of the
trachea. In some breeds, particularly the tea-cup and toy breeds, such
as Chihuahua, Poodles, Yorkies etc, the trachea has a tendency to
collapse from this negative pressure. This is due in part from the small
size of the trachea as well as inherent weakness in the cartilage rings
of the trachea. To visualize what is happening, think about what happens
to a paper straw when you suck on it. At first it allows the liquid to
come up, but when it gets weakened, the sucking action may cause the
straw to collapse.
When the trachea collapses, the membrane from the top may touch the
bottom of the trachea and start a coughing reflex. Moreover, the
collapsing causes the airway diameter to shrink and thus make it more
difficult to breath. As a result, the pet may try to breath harder
causing even more collapse and start a vicious cycle of coughing.
How do we diagnose collapsing trachea?
Collapsing trachea is diagnosed with a combination of a through physical
examination, x-rays of the chest and neck, and direct visulization of
the collapsing trachea through the use of endoscopic equipment. Many
pets with collapsing trachea problems may also develop heart problems,
bronchitis and/or pneumonia and so a thorough workup is indicated.
How do we treat collapsing trachea?
Treatment of collapsing trachea is dependant on the severity of the
problem and the presence of contributing problems such as heart failure
or pneumonia. In the simplest form a treatment, anti-cough medication
may be prescribed. If the problem worsens, sometimes we have to add
broncho dilators or steroid drugs to reduce inflammation. Finally, for
the very worst cases, there is a surgical procedure to implant a plastic
stent to help hold the trachea open during breathing. This surgery is
not without complications and should be considered only after medical
management is not working.
We always warn owners of dogs with collapsing trachea not to use any
neck collars or leashes, to avoid excitement for their pets and to avoid
heat stresses. In addition, it is important to pursue scrupulous oral
hygiene because these pets are very prone to infection, which can come
from the oral cavity.
What is the prognosis for collapsing
trachea?
Collapsing trachea is a serious problem and can even lead to the demise
of your pet. With early diagnosis and treatment, these pets can lead
relatively normal lives but they are at increased risk of serious
respiratory and cardiac problems. Pets with collapsing trachea should be
examined twice yearly, have their teeth cleaned at least once yearly and
have chest x-rays performed yearly.
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