In case you cannot read the link, I am printing this out:
"The trachea, also known as the windpipe, is an important structure which connects the throat to the lungs. It is composed of 35- 45 C-shaped rings of cartilage that are joined by muscle and ligaments to create a tube-like structure. It serves the purpose of directing air into the respiratory tract.
When the cartilage rings are flattened from the top to the bottom, the trachea is said to be collapsed. Rapid inhalation of air can cause the trachea to flatten and make it difficult for air to enter the lungs, much like a soda straw being drawn on too vigorously.
Why does it happen?
We do not completely understand how this condition develops. However, we know that these dogs have an abnormality in the chemical makeup of their tracheal rings. The rings loose their stiffness so they are not able to retain their circular shape. We also know that it occurs in certain breeds of dogs, notably Chihuahuas, Pomeranians, Shih Tzus, Lhasa Apsos, Toy Poodles, and Yorkshire Terriers. Because of that, it is suspected that there is a genetic factor involved.
What are the signs?
Collapsing trachea or Reverse sneezing
With reverse sneezing the pharynx (back of the throat) goes into spasms. The dog finds it difficult to draw in air through the spasms, so it stands still, stretches out her neck, and thrusts its elbows out (like a bowlegged bulldog) as it honks, wheezes, or snorts. Often eyes open wide. The spasms will stop if she swallows a couple of times.
Close off her nostrils with your fingers so it has to breathe through its mouth for a few seconds. Gently rub its throat. This works for some. Distract it by carrying the dog outside into the fresh air.
Young puppies can reverse sneeze, but the first episode typically occurs in late adolescence. Stay calm and get it to swallow with one of the methods described above. In a few seconds to a minute, it will run off to play. Reverse sneezing is a harmless phenomenon which needs no vet consultation and no medical treatment whatsoever. It is very common in toy breeds.
Other signs, however, will help you distinguish the two conditions: If it makes these sounds when excited or after eating or drinking, or turns her elbows outward and extends its neck and gasps inward with a rhythmic snork! snork! snork!, this is reverse sneezing. If it breathes through the mouth sometimes, or breathes with a raspy sound, or coughs reflexively when you simply rub its throat, it could have a collapsing trachea. If the cough is one or two expulsive outward bursts (forcing air through the trachea to open it), typically with a gag or empty retch at the end, she could have a collapsing trachea.
The most common clinical sign of collapsing trachea is a chronic cough. It is often described as dry and harsh and can become quite pronounced. The term "goose honk" is often used to describe it. Coughing is often worse in the daytime and much less at night. The cough may also begin due to excitement, pressure on the trachea (from a leash), or from drinking water or eating."
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Try the suggested treatments and let me know if it helps.