The trachea is a fairly rigid tube (also known as the windpipe) that stretches from a dog's
neck to his chest and brings air into the lungs.
The structure is made of cartilage rings; which can become weak and misshapen over time, causing varying degrees of windpipe obstruction. This condition most commonly affects small breed dogs; such as Chihuahuas, Poodles, Pomeranians, etc.
Why tracheal collapse occurs is unknown.
Signs of tracheal collapse include a honking cough as well as exercise intolerance, labored breathing and a bluish tinge to the gums.