OBSERVATIONS ON DISEASES OF THE HEART OF 
THE HORSE. 
By M?\ Pritchard, F-S"., Wolverhampton. 
It is now my intention to oiFer some remarks on the several 
diseases of the heart, to elucidate, in some measure, those cases 
which have already appeared from my pen in this Journal; and 
I wish I could do the subject that justice so important a part of 
equine pathology demands. It is of the greatest importance that 
we should possess the primary cause of these serious and ulti¬ 
mately destructive changes in the structure of this organ; for, 
although such information may afford but little assistance to the 
preventive or curative treatment of these maladies, it is gratify¬ 
ing and satisfactory to be in possession of the whole facts con¬ 
nected with the origin, progress, and termination of these affec¬ 
tions. 
It has always struck me forcibly that over-exertion is the prin¬ 
cipal exciting cause of hypertrophy and of dilatation, and, I may 
add, the possibility that the original structure of the heart may, 
in some subjects, be unequal in power to the office it is designed 
to perform. This opinion is strongly supported. Horses, parti¬ 
cularly those employed in quick draught, are commonly called 
on to perform arduous tasks with full stomachs, by which the 
free action of the lungs is considerable impeded; thus, obstruc¬ 
tion being given to the circulation through the pulmonary ves¬ 
sels, corresponding increase of force in the action of the heart is 
the consequence. Thus viewing the subject, hypertrophy may 
result to the organ as nature’s resort to increase the propelling 
medium of the circulation, at the sacrifice, injury, and destruc¬ 
tion of the more delicate structures in other important organs 
immediately engaged in life. 
Dilatation of the heart’s cavities may arise in animals in which 
the muscular fibre of the organ is easily extensible, and that oc¬ 
casionally are required to perform undue or unprepared-for exer¬ 
tion; thus we may readily account for the right side being more 
commonly dilated than the left. The first inconvenience felt by 
the animal in exertion is in the respiratory organs, and this more 
especially when the stomach is distended, as then the cavity of 
the chest is diminished ; the lungs are not inflated with ease to 
the extent required for the blood to flow uninterruptedly through 
them. The free circulation of the blood through the lungs being 
thus impeded, the heart acts with increased force, to send that 
fluid through the pulmonary vessels; and, at the same time, con¬ 
tracting on a larger volume of blood, extension of the walls of 
