The trachea is meant to be a fairly rigid tube consisting of a tracheal membrane connecting a group of C-shaped cartilage rings. In some dogs, the C-shaped cartilage becomes weak and begins to flatten out dorsoventrally. When the cartilage loses its curvature, the tracheal membrane becomes slack and instead of being a tight muscle canopy, the flimsy membrane moves as air passes through the trachea...
A 13-year-old female spayed Yorkshire Terrier, weighing 6.1 kg, was referred to the Internal Medicine Service of The Animal Medical Center for hypercalcemia and hyperkalemia. Active medical problems included mild stable azotemia of 11 months duration (International Renal Interest Society Stage II, http://www.iris-kidney.com) and collapsing trachea. The owner also reported a lifelong history of infrequent seizures.
Gone are the days when testing for infectious diseases was simple. There was culture for most bacteria, serology for heartworm, many of the rickettsia and fungal organisms, cytology, fecal float and smears and…really not much more. Well that has changed over the last few years.