DISEASES OF HORSES 93 



may be produced by a primary irritation of the nerve centers of the 

 brain from the effects of heat, as is seen in thermic fever, or sun- 

 stroke, or by the entrance into the blood stream of disease-producing 

 organisms or their chemical products, as in anthrax, rinderpest, 

 influenza, etc. 



There are times when it is difficult to distinguish between the 

 existence of fever as a disease and a temporary feverish condition, 

 which is the result of excessive work. Like the condition of con- 

 gestion of the lungs, which is normal up to a certain degree in the 

 lungs of a race horse after a severe race, and morbid when it produces 

 more than temporary phenomena or when it causes distinct lesions, 

 the temperature may rise from physiological causes as much as four 

 degrees, so fever, or, as it is better termed, a feverish condition, may 

 follow any work or other employment of energy in which excessive 

 tissue change has taken place ; but if the consequences are ephemeral, 

 and no recognizable lesion is apparent, it is not considered morbid. 

 This condition, however, may predispose to severe organic disturb- 

 ance and local inflammations which will cause disease, as an animal 

 in this condition is liable to take cold and develop lung fever or a 

 severe enteritis, if chilled or otherwise exposed. 



Fever in all animals is characterized by the same general phe- 

 nomena, but we find the intensity of the symptoms modified by the 

 species of animals affected, by the races which subdivide the species, 

 by the families which form groups of the races, and by certain con- 

 ditions in individuals themselves. For example, a pricked foot in a 

 Thoroughbred may cause intense fever, while the same injury in the 

 foot of a Clydesdale may scarcely cause a visible general symptom. 

 In the horse, fever produces the following symptoms : The normal 

 body temperature, which varies from 99 to 100 F., is elevated 

 from 1 to 9. A temperature of 102 or 103 F. is moderate fever, 

 104 to 105 F. is high, and 106 F. and over is excessive. The tem- 

 perature is accurately measured by means of a clinical thermometer 

 inserted in the rectum. 



This elevation of temperature can readily be felt by the hand 

 placed in the mouth of the animal, or in the rectum, and in the cleft 

 between the hind legs. It is usually applicable at any point over the 

 surface of the body and in the expired air emitted from the nostrils. 

 The ears and canons are often as hot as the rest of the body, but 

 are sometimes cold, which denotes a debility in the circulation and 

 irregular distribution of the blood. The pulse, which in a healthy 

 horse is felt beating about 42 to 48 times in the minute, is increased 

 to 60, 70, 90, or even 100. The respirations are increased from 14 

 or 16 to 24, 30, 36, or even more. With the commencement of a 

 fever the horse usually has its appetite diminished, or it may have 

 total loss of appetite if the fever is excessive. There is, however, a 

 vast difference among horses in this regard. "With the same amount 

 of elevation of temperature one horse may lose its appetite entirely, 

 while others, usually of the more common sort, will eat at hay 

 throughout the course of the fever, and will even continue to eat oats 

 or other grains. Thirst is usually increased, but the animal desires 



