68 KENNEL DISEASES. 
ened and labored heart action after exertion, also hurried and difficult respiration, 
blueness of the lips and mucous membranes elsewhere, digestive and nutritive dis- 
turbances, and finally kidney complication and dropsy. 
Notwithstanding serious defects in the valves and obstructions in circulation, 
for which there is no cure, the victim may live and be in seemingly fair health 
for several years. 
HYPERTROPHY OF THE HEART. 
As previously stated, when its valves are defective or there is resistanee to 
the passage of the blood, the heart is forced to work harder to maintain proper 
circulation ; and to enable it to meet the increased demands it slowly enlarges or 
undergoes hypertrophy, up to a certain point. Hypertrophy may, however, result 
from habitually excessive exertion, as in coursing and jumping. Quite invariably 
this change is at first uniform, all parts alike undergoing enlargement; and if 
the heart were not forced to over-labor very hard, it would likely remain merely 
larger than normal, and not experience any change that could lessen its powers 
or be prejudicial to health. In other words, were it well nourished, allowed in- 
tervals of rest, —the excessive exertion occurring only occasionally and not habit- 
ually, —and the increased demands stopped within certain limits, like any other 
muscle the heart would grow with exercise, and there be nothing really abnormal 
in its enlargement. But, as a rule, when forced to labor unduly, and always 
where the blood does not circulate as it ought because of valvular obstruction, 
the trouble that occasions the overwork grows steadily more pronounced and 
serious; therefore the enlargement must continue after the safety-lines have been 
reached. It is then not limited to muscular growth and thickening of the walls. . 
The latter become steadily thinner, and the heart is stretched or dilated, and in 
corresponding degree it weakens continuously. 
Only a professional can determine when hypertrophy of the heart exists. 
Manifestly the proper treatment for it is to lessen the amount of work and 
exercise. 
FATTY DEGENERATION OF THE HEART. 
When dogs become obese, fat is deposited throughout the system, no part 
being exempt from the infliction. In the heart, as well as in the kidneys, liver 
and other organs, it is embedded, and invariably seriously weakens if its amount 
is considerable and sufficient to interfere with organic workings. It is a well- 
known fact that a lean muscle is stronger and more enduring than one that has 
had a considerable proportion of its fibres displaced by oil globules or fat; and 
