MEGRIMS. 137 



bedded in the brain of oxen and sheep. Their existence is usually fatal to the 

 animal. There is no well- authenticated account of the existence of an hydatid 

 in the cranial cavity of the horse ; but cysts, containing a serous or viscid fluid, 

 are occasionally observed. The following is the history of one : A horse 

 exhibited symptoms of vertigo, or staggers, which disappeared after copious 

 bleeding and purgatives. About twelve months afterwards the same complaint 

 was evident. He carried his head low and inclined to the right side. 

 He staggered as he walked, and the motion of his limbs was marked by a 

 peculiar convulsive action, confined to the fore extremities. He moved by a 

 succession of spasmodic boundings. He was completely deaf; and rapidly lost 

 flesh, though he ate and drank voraciously. He remained in this state, to the 

 shame of the owner and the practitioner, several months, and then he had a fresh 

 attack of vertigo, and died suddenly. On examination of the brain, its mem- 

 branes were found to be completely reddened ; and, between the two lobes of 

 the brain, was a round cyst as large as a pullet's egg. The pressure of this was 

 the manifest cause of the mischief. 



PRESSURE ON THE BRAIN. 



This may be produced by some fluid thrown out between the membranes, or 

 occupying and distending the ventricles of the brain. In the full-grown horse 

 it rarely occurs ; but it is well known to breeders as an occasional disease of 

 the foal, under the name of " water in the head." The head is either much 

 enlarged, or strangely deformed, or both ; and the animal dies, either in the 

 birth, or a few days after it. 



MEGRIMS. 



There is another kind of pressure on the brain, resulting from an unusual 

 determination or flow of blood to it. This organ requires a large supply of blood 

 to enable it to discharge its important functions. Nature, in the horse more 

 than in many other animals, has made some admirable provisions to cause this 

 stream to flow into the brain with little velocity, and thereby to lessen the risk 

 of suddenly overloading it or rupturing its vessels. The arteries pursue their 

 course to the brain in a strangely winding and circuitous manner ; and they 

 enter the skull through bony apertures that will admit of the enlargement 

 of the vessels only to a very limited extent. From various causes, however, 

 of which the most common is violent exercise on a hot day, and the horse being 

 fat and full of blood, more than the usual quantity is sent to the head ; or, 

 from some negligence about the harness as the collar being too small, or the 

 curb-rein too tight the blood is prevented from returning from the head. 

 The larger vessels of the brain will then be too long and injuriously distended ; 

 and, what is of more consequence, the small vessels that permeate the sub- 

 stance of the brain will be enlarged, and the bulk of the brain increased, so that 

 it will press upon the origins of the nerves, and produce, almost without warn- 

 ing, loss of power and consciousness. 



The mildest affection of this kind is known by the name of MEGRIMS. It 

 comparatively rarely happens when the horse is ridden ; but should he be driven, 

 and perhaps rather quickly, he may perform a part of his journey with- his 

 usual cheerfulness and ease : he will then suddenly stop, shake his head, and 

 exhibit evident giddiness, and half-unconsciousness. In a minute or two thia 

 will pass over, and he will go on again as if nothing had happened. 



Occasionally, however, the attack will be of a more serious nature. He will fall 

 without the slightest warning, or suddenly run round once or twice, and then 

 fall. He will either lie in a state of complete insensibility, or struggle with 

 the utmost violence. In five or ten minutes he will begin gradually to come 

 to himself; he will get up and proceed on his journey, yet somewhat dull, and 



