The Classic Comprehensive Handbook of Cat Care
RESPIRATORY SYSTEM
The cat’s respiratory system consists of two lungs, the air passages leading to them (nasal cavity, mouth, pharynx, larynx, trachea, bronchi), the diaphragm, and the muscles of the thorax. The system’s main function, as in humans, is to supply oxygen to the body and to remove excess carbon dioxide produced by metabolism. In conjunction with the tongue and the mucous membranes of the mouth, the respiratory system has a secondary but extremely important function of heat regulation, since the cat has no highly developed mechanism for sweating. Unlike dogs, however, cats rely on panting for cooling only under extreme heat stress. The nostrils and nasal passages are also important to the cat’s highly developed sense of smell.
The only parts of your cat’s respiratory system you can see are the mouth and nostrils. Special instruments are needed to look into the nasal cavity; and this is difficult, even with special instruments, because the passages are so small. Look at your cat’s nostrils. Any secretions from them should be clear and watery; sticky, cloudy, bloody, yellowish or greenish nasal discharge is abnormal.
You can feel your cat’s larynx (Adam’s apple) by grasping the neck on the undersurface where it meets the head. The larynx feels like a small, hard, fairly inflexible mass of tissue. It helps control the flow of air through the trachea and lungs and is the location of the vocal cords responsible for your cat’s meow. The purr also originates in the larynx. When certain muscles within it contract narrowing its opening (the glottis), the air turbulence created during breathing results in the purring sound.
Notice the character of your cat’s respirations at rest and after exercise.
A normal cat at rest breathes about twenty to thirty times per minute. The movements of the chest are smooth and unstrained. After exercise, of course, the rate is much faster, and on very hot days or during periods of extreme excitement the rate increases above normal and panting may occur. Changes in the rate and character of a cat’s respiration may indicate disease. Be sure to become familiar with your cat’s normal breathing at rest, on cool and warm days, and during and after exercise so you can tell when changes have occurred.