374 DISEASES OF THE BRAIN AND NERVES. 



may also be mingled with the bran ; to which must be 

 added five ounces of anise, of fennel, and of coriander seed. 

 This quantity will be sufficient for thirty sheep. Every 

 animal attacked, which is to be discovered by turning up 

 the eyelid, when the conjunctival membrane will be seen of 

 a yellow colour, should have the following drench daily : — 



Oil of turpentine two draclims. 



Carbonate of soda one drachm. 



Water four ounces. 



CHAPTER IV. 



DISEASES OF THE BRAIN AND NERVES. 



We shall commence a consideration of the individual dis- 

 eases of this class by some general observations on the 

 origin of affections of the nervous system generally. In 

 the horse, the nervous mass is greatly superior to the cere- 

 bral ; and we find that affections of the spinal cord are 

 in this generous animal more numerous. An apoplectic 

 termination to human life is by no means uncommon ; 

 in the horse it is little known ; but the frequency with 

 which spinal affections occur, bear little proportion be- 

 tween the two ; and taking all the circumstances into con- 

 sideration, are more than equal to the nervous affections 

 of mankind. Dissections of morbid subjects have also 

 shown that the causes are various, but are usually referrible 

 either to pressure on the spinal cord, or otherwise are 

 attributable to a morbid alteration of structure in the cord 

 itself. 



Pressure on the spinal marrow may be the consequence 

 of either wounds or over exertion ; or it may originate in 

 the existence of parasites within the canal. Lesions, occa- 

 sioning wounds, are very common from fractures of some 

 of the vertebrae, or from dislocation of the same bones : an 

 aneurism of the aorta has produced it ; exostosis and poll- 

 evil have also done the same ; the one by ulceration through 

 the articular membranes, and the other by an osseous de- 

 posit within the canal. Debility, resulting from over 

 exertion, causes either sanguineous congestion, or other- 

 wise it is accompanied with an increased effusion of inter- 



