522 DISEASES OP THE HOKSE. 



tuous; the mucous membranes assume a brighter and more distinct 

 color; the difficulty of respiration is removed, and the animal may 

 make a recovery. When death occurs it is usually directly due to 

 heart failure; in some cases it is caused by asphyxia, owing to the 

 great amount of exudation into the lung tissue, rendering its fur- 

 ther function impossible. 



Complications. — The pulmonary complications of edematous pneu- 

 monia are secondary inflammatory or necrotic changes in the lungs 

 themselves. Suppuration at times takes place in the bronchi and may 

 extend to the lung tissue. In this case mucous rales develop which are 

 most distinctly heard over the trachea and on the sides of the chest 

 directly behind the shoulders. With the development of the mucous 

 rales, to be heard on auscultation, we have a more purulent discharge 

 from the nostrils, similar to that of a chronic or subacute bronchitis. 

 If the inflammation has been of some standing, cavernous rales may 

 be heard indicating the destruction of a considerable portion of lung 

 tissue and the formation of a cavity. The effects of this more acute 

 inflammatory process are not appreciable in the general condition of 

 the animal, except to still further weaken it and add to its debili- 

 tated and emaciated cachexia. Gangrene sometimes occurs. A sud- 

 den rise of the body temperature of 1° or 2°, with a more enfeebled 

 pulse and a still more tumultuous heart, develop simultaneously with 

 the appearance of a discharge from the nostrils. This discharge is 

 gray in color, serous or watery in consistency, mixed with the detritus 

 of broken-down lung tissue, and sometimes contains clots of blood, or 

 in more serious cases may be marked by a quantity of fluid blood 

 from a hemorrhage, which proves fatal. The discharge is fetid to the 

 smell. The animal emaciates rapidly. On examination of the lungs 

 mucous rales are heard in the larger bronchi, cavities may be found at 

 any part of these organs, and points of lobular pneumonia may be 

 detected. 



A very serious complication is an inflammation of the heart mus- 

 cle. This is shown by a very weak and rapid pulse, great prostration, 

 some filling of the lungs. This complication nearly always terminates 

 in death. Other complications which may be mentioned are inflam- 

 mation of the kidneys, blood poisoning, congestion of the brain, and 

 inflammation of the tendinous sheaths and the tendons of the legs. 



Diagnosis. — ^As fever is the first symptom of edematous pneumonia, 

 it is useful during an outbreak of this disease to make daily tempera- 

 ture measurements of the exposed horses, so that the first indication 

 of disease may be discovered and the horse removed from contact with 

 those that are sound. 



Prognosis. — The mortality in this disease may be as high as 25 per 

 cent, but it is usually not more than 10 per cent. If there is a special 

 tendency to complications of some sort, the mortality is increased, 



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