228 VETERINARY STUDIES 



over-ripeness are probably not the only factors. Many eases of 

 heaves may be due to fungi, especially their spores, rather than 

 to the character of the food with which the fungi are taken. 



Symptoms. — A peculiar, explosive cough usually appears be- 

 fore the breathing becomes noticeably disturbed. After a time 

 it is noticed that exercise produces unusual difficulty in breath- 

 ing, the air being taken in quite easily but expelled with dif- 

 ficulty. When this stage develops, the air is expelled in two 

 efforts instead of one, the latter portion of the tidal air being 

 expelled by a special effort of the belly muscles. Overfeeding, 

 of course, increases the difficulty. 



Some cases of heaves may be disguised temporarily by the 

 use of drugs and the feeding of a concentrated diet. This trick 

 may usually be detected, however, by allowing the horse a 

 hearty feed and water, and then giving active exercise or even 

 by actively exercising him without the special feeding and water- 

 ing. A horse drugged with any belladonna preparation shows 

 greatly enlarged pupils of the eyes. It is usually easy to dis- 

 tinguish between heaves and roaring. The latter is a disease 

 of the larynx due to paralysis of one of the laryngeal carti- 

 lages and is shown by the abnormal sounds known as roaring 

 or whistling during inspiration, the movements of the flank and 

 chest being normal. 



Prevention. — The prevention of most cases of heaves may be 

 easily described and almost as easily accomplished — by mere 

 avoidance of well-known causes. There is a very general and 

 wasteful feeding of hay. This is not merely a waste; it is an 

 injury to the horse. A case of heaves due to over-feeding is 

 usually discredit to the feeder. Heaves often indicates that 

 the horse is a good feeder and under wiser management would 

 be able to digest a large amount of food and do hard work. 

 There is no satisfactory evidence that heaves is hereditary, and 

 no proof to the contrary. 



It is not wise to allow a horse to do very fast or hard work 

 on a distended stomach, which means that the work should be 

 slower and easier during the first hour or so after hearty meals. 

 Little hay should be fed in the morning, and at noon, and a 

 reasonable quantity in the evening. 



To prevent heaves, then, feed reasonable quantities of good 

 wild hay, or tame hay cut early and not allowed to become 

 musty. Avoid dusty foods. The amount of hay should be 



