16 DISEASES OF THE HORSE. 



and above this point it is regarded as very high. In some diseases, 

 such as tetanus or sunstroke, the temperature goes as high as 108° or 

 110°. In the ordinary infectious diseases it does not often exceed 

 106°. A temperature of 107.5° and above is very dangerous and must 

 be reduced" promptly if the horse is to be saved. 



THE ORGANS OF RESPIRATION. 



In examining this system of organs and their functions it is cus- 

 tomary to begin by noting the frequency of the respiratory move- 

 ments. This point can be determined by observing the motions of 

 the nostrils or of the flanks ; on a cold day one can see the condensa- 

 tion of the moisture of the warm air as it comes from the lungs. The 

 normal rate of respiration for a healthy horse at rest is from 8 to 16 

 per minute. The rate is faster in young animals than in old, and is 

 increased by work, hot weather, overfilling of the stomach, preg- 

 nancy, lying upon the side, etc. Acceleration of the respiratory rate 

 where no physiological cause operates is due to a variety of condi- 

 tions. Among these is fever; restricted area of active lung tissue, 

 from filling of portions of the lungs with inflanmiatory exudate, as 

 in pneumonia; compression of the lungs or loss of elasticity; pain 

 in the muscles controlling the respiratory movements; excess of 

 carbon dioxid in the blood; and constriction of the air passages 

 leading to the lungs. 



Difficult or labored respiration is known as dyspnea. It occurs 

 when it is difficult, for any reason, for the animal to obtain the 

 amount of oxygen that it requires. This may be due to filling of the 

 lungs, as in pneumonia; to painful movements of the chest, as in 

 rheumatism or pleurisy; to tumors of the nose and paralysis of the 

 throat, swellings of the throat, foreign bodies, or weakness of the 

 respiratory passages, fluid in the chest cavity, adhesions between 

 the lungs and chest walls, loss of elasticity of the lungs, etc. Where 

 the difficulty is great the accessory muscles of respiration are brought 

 into play. In great dyspnea the horse stands with his front feet 

 apart, with his neck straight out, and his head extended upon his 

 neck. The nostrils are widely dilated, the face has an anxious ex- 

 pression, the eyeballs protrude, the up-and-down motion of the 

 larnyx is aggravated, the amplitude of the movement of the chest 

 walls increased, and the flanks heave. 



The expired air is of about the temperature of the body. It con- 

 tains considerable moisture, and it should come with equal force from 

 each nostril and should not have an unpleasant odor. If the stream 

 of air from one nostril is stronger than from the other, there is an 

 indication of an obstruction in a nasal chamber. If the air possesses 

 a bad odor, it is usually an indication of putrefaction of a tissue or 



