THE RESPIRATORY ORGANS 325 



520. The second form is of much more importance, and is due to 

 structural change in the lungs ; some of the small air cells having 

 become ruptured, the air finds its way through the tissue of the lungs 

 to beneath the pleura, and gives the surface of the lungs a blubbery 

 appearance, called emphysema. This form of the malady is at 

 times due to a bad attack of influenza, bronchitis, or pneumonia, 

 but more frequently it is caused by bad food — particularly musty 

 hay and corn — or by putting the animal to too hard an exertion, 

 such as starting off full trot immediately after feeding. Such causes 

 act not only mechanically, but also on the gastric branches of the 

 pneumogastric nerve, which, by reflex action, implicate the lung or 

 chest branches. As this form of complaint is incurable, the great 

 point is to get the animal to work comfortably, and for this purpose 

 the feeding must be regulated ; nutritious diet of not too bulky a 

 character ought to be given, and plenty of fresh air allowed. A case 

 of this kind does best out of doors. The affected animal alwavs has 

 a peculiar way of breathing. The inspiration is performed with 

 comparative ease, but the expiratory effort is double, the flank falling 

 with a jerky motion. The cough is also noticeable, being a long, 

 dry, droning bark, which is characteristic of the disease. On apply- 

 ing the ear to the lower part of the windpipe, a crackling, hissing 

 sound is also to be heard in the lungs. Treatment is of little avail, but 

 a cough ball may be given every night for a week {par. 1064, No. II.); 

 but from 2 or 3 grain doses of arsenic once a day for ten days or a 

 fortnight given in a mash answers best. 



521. Formerly, unprincipled dealers used to practise all sorts of 

 tricks in selling an animal thus affected, such as pouring 1 or 2 pounds 

 of lead shot, with a pound of melted butter, down the horse's throat. 

 This weighed the stomach down, taking the pressure off the dia- 

 phragm, and thus allowed the lungs more play, when the horse 

 breathed almost naturally. Another practice was to cut a hole into 

 the abdominal cavity close to the rectum, when the air, being allowed 

 access, rushed in, and had the effect of assisting the breathing, and 

 this also seemed to have a controlling action on the double breathing. 

 I have seen a few cases of this trick in the early part of my profes- 

 sional career, but they are rare nowadays. 



