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MKGRIMS OR VERTIGO. 277 



562. Syynptoms. 



The attack is very sudden and peculiar. There are seldom any pre- 

 monitory symptoms. The animal suddenly shakes and throws up his 

 head, or shakes it violently, or reels, and then stands for a minute or two 

 dull and listless, or runs round and falls to the ground, remaining for a 

 few moments partially insensible or in a state of violent convulsion. Tho 

 attack rapidly passes away, the horse rises in a minute or two, shakes 

 himself, and proceeds as if nothing had happened, though perhaps he may 

 appear somewhat debilitated. During the fit he may stale or dung 

 insensibly. The attacks are usually periodical, and occur chiefly during 

 hot weather and at severe harness work. 



There is seldom any outward sign which indicates liability to this 

 disease. On the contrary the horse looks well, has a good appetite, and 

 shows no special nervousness or dulnees. The best Veterinary Surgeon 

 cannot detect a possible liability to this disease, and post-mortem exami- 

 nation also sometimes fails to reveal the cause. 



Certain sorts of horses are, however, more liable to it than others, such 

 for instance as those known as star-gazers, with an erect and stiff neck, 

 also those with an awkward protrusion of the nose, with the head so set 

 on that it is difficult to be reined in. It has also been observed to be 

 more common in animals that carry their heads on one side than in 

 others. 



563. Predisposing causes. 



Though we cannot assign the positive causes of this disease, yet it is 

 pretty certain that it is connected with retardation of the flow of blood 

 from the brain. Harness horses are far more subject to it than saddle 

 horses. Many horses, which suffer from it in the collar, are free from it 

 at other times. The collar, probably by retarding the blood returning 

 from the brain, appears specially to predispose to it. 



Various other circumstances also appear indirectly to develop the 

 disease, and to increase or diminish the chance of its reciu'rence. Hot 

 weather, bright sun, and high temper certainly predispose to it. Tight 

 reining up and bearing reins, probably by retarding the return of the 

 blood from the head, develop it. Severe work and bad feeding on the 

 one hand, and high feeding and little work on the other hand, are both 

 apt to bring it on. Fair condition and moderate work diminish the 

 tendency to attacks. Horses, which have lost a vein from the effect of 

 clumsy bleeding, are said to be predisposed to it. 



It has been noticed as a practical fact, that horses are more often 

 attacked during the intervals of sunshine, which sometimes occur on hot 

 cloudy days in summer, than at any other time. 



564. Treatment. 



As regards treatment of the actual attack, beyond the free use of cold 

 ■water douches to the head we have none to recommend. As a preventive 

 we can only advise that the animal be kept in fair, not very hio-h condi- 



