Lungs and collapsed trachea, canine

Canine trachea (windpipe) and lungs, photograph. The trachea is supported by c-shaped open rings of collagen, covered in muscle. Weakening of the cartilage rings causes them to collapse, flattening the trachea. Severe flattening can obstruct the trachea, causing breathing difficulties and respiratory distress. Tracheal collapse typically affects middle-aged and elderly small breed dogs such as Yorkshire terriers.