128 DISEASES OF THE HORSE. 
that the hemorrhage is so profuse as to require internal remedies. 
But hemorrhage into the lung may occur and cause death by suffo- 
cation without the least manifestation of it by the discharge of blood 
from the nose. 
TUBERCULOSIS OF THE LUNGS. 
Pulmonary consumption or tuberculosis has been recognized in 
the horse in a number of instances. The symptoms are as of chronic 
pneumonia or pleurisy. There is no treatment for the disease. 
HEAVES, BROKEN WIND, OR ASTHMA. 
Much confusion exists in the popular mind in regard to the nature 
of heaves. Many horsemen loosely apply the term to all ailments 
where the breathing is difficult or noisy. Scientific veterinarians are 
well acquainted with the phenomena and locality of the affection, but 
there is a great diversity of opinion as regards the exact cause. 
Asthma is generally thought to be caused by spasm of the small cir- 
cular muscles that surround the bronchial tubes. The continued 
existence of this affection of the muscles leads to a paralysis of them, 
and the forced breathing to emphysema, which always accompanies 
heaves, 
Heaves is usually associated with disorder of the function of diges- 
tion or to an error in the choice of feed. Feeding on clover hay or 
damaged hay or straw, too bulky and innutritious feed, and keeping 
the horse in a dusty atmosphere or a badly ventilated stable produce 
or predispose to heaves. Horses brought from a high to a low level 
are predisposed. 
In itself broken wind is not a fatal disease, but death is generally 
caused by an affection closely connected with it. After death, if the 
organs are examined, the lesions found depend much upon the length 
of time broken wind has affected the animal. In recent cases very 
few changes are noticeable, but in animals that have been broken- 
winded for a long time the changes are well marked. The lungs are 
paler than natural, and of much less weight in proportion to the vol- 
ume, as evidenced by floating them in water. The walls of the small: 
bronchial tubes and the membrane of the larger tubes are thickened. 
The right side of the heart is enlarged and its cavities dilated. The 
stomach is enlarged and its walls stretched. The important change 
found in the lungs is a condition technically called pulmonary em- 
physema. This is of two varieties: First, what is termed “ vesicular 
emphysema,” which consists of an enlargement of the capacity of the 
air cells (air vesicles) by dilation of their walls. The second form 
is called interlobular, or interstitial, emphysema, and follows the 
