RUPTURE OF THE LEFT VALVE OF THE HEART. 173 
On the 14th of October she was again returned to my in- 
firmary on account of the frequent occurrence of these fits. I 
watched her carefully. The spasmodic beatings of the heart were 
very violent, and the motion produced by them was propagated 
over the whole of the body whenever the animal took any consi- 
derable exercise. I bled her twice in eight days, and adminis- 
tered several doses of foxglove to her. The fits appeared to be- 
come less frequent, but on the 28th of October the animal fell 
for the last time, and expired immediately. 
The post-mortem examination was made two hours after death. 
The cavity of the pericardium contained a red clot of blood which 
enveloped the whole of the heart ; it was thicker in the parts 
which corresponded with the valve of the heart and on the left 
ventricle. Near the base of the left valve of the heart, on the 
external part of that viscus was an irregular rent two inches long. 
It crossed the wall of the valve of the heart, which was very thin 
in this place. The size of the heart was very small considering 
the height and bulk of the dog. The walls of the ventricles, and 
particularly of the left ventricle, were very thick. The cavity of 
the left ventricle was very small. There was evidently a concen- 
tric hypertrophy of these ventricles*. The left valve of the heart 
was of great size and the heart of very small dimensions, at least 
relative to the surfaces. 
The immediate cause of the rupture of the valve of the heart 
had evidently been an increase of circulation, brought on by an 
increase of exercise, but the remote cause consisted in the re- 
markable thinness of the walls of the valve of the heart. This 
case is remarkable in more than one respect: first, because 
examples of rupture of the valve of the heart are very rare ; and, 
secondly, because this rupture had its seat in the left valve of the 
heart, while usually, in both the human being and the quadruped, 
it takes place in the right, and this, without doubt, because the 
walls of that valve actually are thinner. 
* In 1840, I published an abridgment of my researches respecting the 
diseases of the heart, and I gave several examples of the normal proportions 
of the heart among horses and dogs. 
