630 
MR. YOUATT’s VETERINARY LECTURES. 
with greatly increased velocity through the lungs, in order that the 
requisite supply of arterial fluid should be furnished ; and if 
through the lungs, likewise through every other part of the frame, 
and the brain among the rest. The arteries supply it more 
rapidly than the veins can carry it off; the distention of the 
arteries, perhaps, causes compression of the veins; and hence 
the circulation is impeded, and there is greater or less pressure 
on the origins of the nerves. 
Megrims in the Horse .—I add to this another cause of conges¬ 
tion of blood in the brain. I am driving my horse; the collar is pro¬ 
bably a little too tight,—it presses on the jugular vein, and pre¬ 
vents the free return of the blood from the head. What is often 
the consequence of this ? Why, the animal begins to go a 
little sluggishly: I, perhaps, take no notice of this, or, not at¬ 
tributing it to its proper cause, urge him to his former speed. 
Presently afterwards he stops—stops sometimes as if he were 
shot—staggers, is deaf to my voice, and scarcely conscious of 
surrounding objects : he backs a little ; the collar ceases to press 
upon his neck, and he recovers : he shakes his head, looks a little 
frightened, and goes on again, but with not quite so much spirit 
as before. This attack is strangely called the megrims . 
A more aggravated Case. —Often, however, the matter does not 
end here. He begins to be unmanageable—he takes a sudden 
fancy to go round and round, and then he staggers and falls; 
or he falls at once; and according to the degree of conges¬ 
tion, or the relief that he may experience from the removal of the 
pressure of the collar, or other causes of which I am ignorant, 
he either lies insensible for awhile, or he begins to struggle most 
violently, or he quickly scrambles up again, frightened at what 
has happened, and afraid of my correction ; and he goes on as if 
nothing was the matter, except that he is dull and languid. These 
cases are not unfrequent, and especially in sultry weather, and then 
the horse sometimes dies on the spot. Many a stage coach- 
horse is thus lost: it is the coup-de-sang as regards him. 
This a State of Sanguineous Congestion .—When we have an 
opportunity of examining the brain in this case, no theoretical 
reasoning of the incompressibility of the brain, and the perfect 
fulness of the cranial cavity, and the impossibility of any material 
variation of the absolute quantity of blood in the brain, can 
deprive me of the evidence of my senses : we find actual accumula¬ 
tion of blood in the vessels of the brain—in the arterial vessels to 
a very great degree, but mostly in the sinuses or other venous 
canals: the membranes are all injected, and deeply so; and 
