OF VETERTXARV MEDICINE. 191 



watery constituents. The animal becomes indolent and his cir- 

 culation is slowed. When he begins to exercise again the circu- 

 lation increases, the pulse in some cases running up to 60; he 

 feels good and takes very active exercise, and as a result of this 

 exercise there is tissue metamorphosis. The waste material pro- 

 duced in the system is nitrogen. Every contraction of the 

 muscles separates the nitrogen from the tissues. The muscles 

 get their nitrogen from certain kinds of food. Tlie surplus 

 nitrogen must be eliminated from the system by the kidneys or it 

 will poison the blood. The kidneys excrete it in the form of 

 urea. The surplus water and salts in the blood of a plethoric 

 animal can be gotten rid of through other channels but the kid- 

 neys must take care of the excess of nitrogen. The thick blood 

 cannot circulate so freely through the organs and we get a 

 capillary stasis, the kidneys become congested and there is an 

 impaction of the capillaries with blood. This interferes with the 

 action of the kidneys and the coloring matter of the blood is 

 forced out into the urine, giving it the dark color which we see 

 in the urine of azoturia. 



The action of the kidneys may be so disturbed that there is 

 total suppression of the urine and the horse may die in two 

 hours; but if the kidneys are partially active then the life of the 

 animal is prolonged. When he recovers, it is because the kid- 

 neys are restored to their normal activity, but if he dies it is 

 because the kidneys cannot eliminate the urea and uraemic poi- 

 soning takes place. Uraemic blood poisoning is the immediate 

 cause of death. Other organs are congested as well as the kid- 

 neys, the lungs especially. As the animal goes down he gives 

 way to a peculiar motor paralysis of the muscles, due to mus- 

 cular congestion. This congestion causes pressure upon the 

 trunk nerves and the muscles become paralyzed. The muscles 

 most often affected c.re the gluteal, posterior portion of ihe dorsal 

 and the anterior crural region. The congestion of these muscles 

 is often so severe as to interrupt the circulation and a cessation 

 of the muscle activity takes place, leading to atrophy. When 

 the congestion is very tense with little swelling, the muscles get 

 hard and the pressure upon the nerves is severe and often 

 fatal. Usually, but not always, the hind parts are affected, more 



