70 THEORY AND PRACTICE 



1. Interrupted nutrition. 



2. Dilatation of the blood vessels. 



3. More or less extravasation. 



4. Sometimes hemorrhage by rhexis. 



In case of hemorrhagic infarction, it is never general 

 throughout the lungs, but in patches, which are black and solid. 



Etiology. — The most common cause of a typical case is se- 

 vere exertion when the animal is not in a condition to take it. 

 This applies to horses. A horse ''out of condition" is gross — 

 has not had sufficient work. The animal is plethoric and there 

 is an excess of fat in and around the muscles and kidneys, which 

 weakens the muscles, and that around the heart weakens the 

 heart. The bowels are larger and more vascular; the blood 

 vessels are larger and the walls are weaker. 



A horse "in condition" to take fast work is in just the reverse 

 condition. 



1. Muscles are clearly delineated ancJ 



hard. 



2. Walls of vessels are strong. 



3. Contractility of the lung tissue is 



strong — weak in horse "out of condi- 

 tion.'* 

 A horse "out of condition" has a weak heart; a horse "in 

 condition" has a strong heart. The conditioning of a horse to 

 do fast work is a slow process, but he must have regular work — 

 work off the surplus water and fat. Let the horse stand in the 

 stable 10 days, well fed, and not exercised, and then be taken out. 

 Then if he starts out at 12 miles an hour the following symp- 

 toms will show up : 



1. Horse begins to blow. 



2. Slows up in his gait. 



3. Short in his wind. 



If the driver has any sense, he will let him slow up. but sup- 

 pose he hits him a crack, and the horse jumps into a quick pace 

 again, then 



4. He breaks out into sweat. 



5. Slows up again. 



6. Looks around — eyes blood-shot. 



