288 The Diseases of Animals 
PULMONARY EMPHYSEMA, HEAVES, OR BROKEN: Winp * 
This is a chronic disease of horses, due to a dilation 
or rupture of the air-cells of the lungs. It is usually 
associated with a chronic form of indigestion. 
Heaves is usually the result of improper food or 
feeding, and is most frequently seen in greedy feeders. 
Overfeeding, especially with dusty or moldy hay, is a 
common cause. Fast driving or hard work on a full 
stomach may induce the disease. There may be an 
hereditary tendency to the disease. 
In most cases, the disease comes on gradually, but 
fast work on a full stomach brings it on suddenly. 
The breathing is labored, the air being taken in (in- 
spired) with a peculiar outward twist of the ribs. 
When the air is forced out (expired), there is a double 
movement of the flank: when expiration begins, 
the flank falls; then there is a short pause. followed 
by a decided contraction of the muscles, which causes 
a heaving of the flank and belly. All the breathing 
symptoms are most distinct when the stomach is full 
of food or water, and the horse is exercised. In most 
eases of heaves there is a deep, moist, grunting cough, 
most frequent when the food or the air is dusty. 
There is considerable gas passed from the bowels, es- 
pecially when coughing. The nostrils are dilated, and 
frequently there is a discharge of thick mueus from 
the nose. Horses badly afflicted with heaves are unable 
to perform hard or fast work without stopping frequently 
to breathe. 
*« Roaring,” due to a paralysis of the museles of the throat, is also called 
“broken-wind” by horsemen. See pages 288-9, 
