NATURE AND CAUSATION. 415 



opinion as to the true nature of chorea, or the agencies which 

 operate in its production. By many it is regarded as simply 

 functional derangement of the great nerve-centres, perverted 

 nerve-force, the result of many and divers influences, or of 

 whatever may produce nervous dynamic disturbances ; others, 

 again, appear rather to view it as the result of a prior deteri- 

 orated or poisoned condition of the blood, the exact nature of 

 which is as yet undetermined ; while a third class accept the 

 entire phenomena as merely concurrent or accompanying 

 S3rmptoms of certain peculiar blood erases, as the rheumatic, or 

 of such general abnormal conditions as are found in connec- 

 tion with cardiac or renal diseases. 



In our patients, with the exception of the dog, the horse is 

 probably the greatest sufferer from various forms of nervo- 

 muscular phenomena, chiefly attractive through the convul- 

 sive action of a clonic character of certain classes of voluntary 

 muscles, which, by almost general consent, we have agreed to 

 designate by the term ' chorea.' That this particular form of 

 nervo-muscular disturbance is correctly described as of a 

 choreic character, or as bearing a close resemblance to the 

 abnormal condition known as chorea in man, there is little 

 doubt ; that it is identical with it, I do not believe. Like 

 chorea in man, it is more frequently seen in young than in old 

 animals. Unlike this disturbance in him, however, it does not 

 seem in any instance to exhibit a disposition to disappear 

 spontaneously, or under the influence of medicine. 



If in some of our patients we may safely regard this dis- 

 turbance as the sequel of, or in some way closely connected 

 with, certain specific fevers, in the horse any such ordering of 

 its causation is rarely possible. Over a considerable number 

 of years I have only met with one case in which any such 

 connection seemed to exist, and this might safely be regarded 

 as merely a fortuitous coincident. The animal was suflering 

 from a serious attack of influenza, from which it ultimately 

 died, and during the continuance of the fever well-marked 

 symptoms of chorea in both anterior and posterior extremities 

 showed themselves, and continued until death. These choreic 

 spasms had either a concurrent existence with the fever, or 

 they were much aggravated by its occurrence, as they had not 

 been previously noticed. The animal certainly had only been 



