DISEASES OF THE HORSE. 119 



Whistlinf/ is only one of the variations of the sound emitted by a 

 horse called a "roarer," and therefore needs no further notice, except 

 to remind the reader that a whistling sound may be produced during 

 an attack of severe sore throat or inflammation of the larynx, which 

 passes away with the disease that causes it. 



CHRONIC BRONCHITIS. 



This ma}^ be due to the same causes as acute bronchitis or it may 

 follow the latter disease. An attack of the chronic form is liable to 

 be converted into acute bronchitis by a very slight cause. This 

 chronic affection in most instances is associated with thickening of the 

 walls of the tubes. Its course is slower, it is less severe, and is not 

 accompanied with as much fever as the acute form. If the animal is 

 exerted, the breathing becomes quickened and he soon shows signs of 

 exhaustion. In many instances the animal keeps up strength and 

 appearances moderately well, but in other cases the appetite is lost, 

 flesh gradually disappears, and he becomes emaciated and debilitated. 

 It is accompanied b}'^ a persistent cough, which in some cases is husky, 

 smothered, or muffled, while in other cases it is hard and clear. A 

 whitish matter is discharged from the nose, which may be curdled in 

 some instances. If the ear is placed against the chest behind the shoulder 

 blade, the rattle of the air passing through the mucus can be heard 

 within. 



Treatment. — Rest is necessary, as even under the most favorable 

 circumstances a cure is difficult to effect. The animal can not stand 

 exertion and should not be compelled to undergo it. The animal 

 should have much the same general care and medical treatment pre- 

 scribed for the acute form. Arsenious acid in tonic doses (3 to 7 grains) 

 three times daily ma\' be given. As arsenic is irritant, it must bo 

 mixed with a considerable bulk of moist feed and never given alone. 

 Arsenic may be given in the form of Fowler's solution, 1 ounce three 

 tunes daily in the drinking water. An application of mustard applied 

 to the breast is a beneficial adjunct. The diet should be the most 

 nourishing. Avoid bulky food. Linseed mashes, scalded oats, and, 

 if in season, grass and green-blade fodder are the best diet. 



THE LUNGS, 



The lungs are the essential organs of respiration. They consist of 

 two (right and left) spongy masses, commonly called the "lights," 

 situated entirely within the thoracic cavity. On account of the space 

 taken up by the heart, the left lung is the smaller. Externally, they 

 are completely covered by the pleura. The structure of the lung 

 consists of a light, soft, but very strong and remarkably elastic tissue, 

 which can only be torn with difficulty. Each lung is divided into a 

 certain number of lobes, which are subdivided into numberless lobules 



