I 
1.36 
SOCIETY MEETINGS. 
great vessels of the neck by collar, etc., the sudden lowering of 
the head, the venous current being retarded by gravitation, 
coughing by increasing the thoracic pressure and so obstructing 
the passing of blood into the right auricle. Second, increased 
arterial supply produced by sudden physical exertion, rigidity 
of the walls of the arteries by diminishing the elasticity and 
so increasing the pressure. The increase in the labyrinth blood 
supply in the human is characterized by vertigo, impairment of 
vision, etc., and why not in our patients ? We are all aware 
that the semicircular canals are closely connected with coordi¬ 
nation of movement and equilibrium, as experiments prove that 
section of one side of them caused incoordination on that side 
and section of both loss of equilibrium. Bpidemic parotiditis 
is particularly apt to affect the labyrinth structures, and recent 
investigations prove this to be due to infection from the blood 
current. The same disease would also affect the middle ear by 
partial occlusion of the Bnstachian tube, thus rendering the air 
pressure on the tympanum unequal, and knowing that this in a 
human being will give rise to symptoms analogous to labyrinth 
vertigo why should it not do so in a horse, and I believe future 
post-mortems will prove that partial occlusion of the Eustachian 
tube is a frequent cause of this trouble. Of course, if this 
disease could be detected during examination, it would, in my 
opinion, constitute an unsoundness. 
DiSCtJSSiON. 
Dr, Walker: I owned a horse which after my having him 
for about six weeks tried to get his head through the wall of 
his stall one night. I got him out and sent him to pasture for 
about two or three months and afterwards sold him. Two or 
three weeks later he was hurt again and I found him to be in 
the exact condition as at the time when I bought him. I think 
that there are some cases where it is quite possible to detect 
them. You will find them to be very bad leaders if you lead 
them from behind, and if a man tries to lead him with a halter 
he is inclined to pull back, but there are many cases where 
they deceive a veterinary surgeon. 
Dr. Robertson: I have never been able to diagnose a case. 
Dr. Baker: Mr. Chairman :—I never had an opportunity of 
making an autopsy on a case of this kind, but they are compara¬ 
tively not rare in practice. I rather admire Dr. Allen’s theory 
with regard to the cause, especially after he had found an occlu¬ 
sion of the Eustachian tube. I think I could suggest as a possi- 
