DISEASES OF THE NERVOUS SYSTEM. 227 



General, irrefjular muscular contractions of various i)arts of the l»ody, 

 witli unconsciousness, characterize Avhat we re<^aril as convulsions, 

 and like ordinary spasms are dependent upon some disease or irrita- 

 tion of the nervous structures, chiefly of the brain. No treatment is 

 required; in fact, a <^eneral convulsion must necessarily be self- 

 limited in its duration, Suspendin*?, as it does, respiratory move- 

 ments, checkini^ the oxygenation and decarbonization of the blood, 

 the rapid accumulation of carbonic-acid gas in the blood ami the 

 exclusion of oxygen quickly puts the blood in a condition to produce 

 the most reliable and speedy sedative effect ujion the nerve excitabil- 

 ity that could be found, and consequently furnishes its own remedy 

 so far as the continuance of the convulsive paroxysm is concerned. 

 AVhatever treatment is instituted must be directed toward a removal 

 of the cause of the convulsive paroxysm. 



CHOREA, OR ST. VITUS'S DANCE. 



Chorea is characterized by involuntary contractions of voluntary 

 muscles. This disease is an obscure disorder, which may be from 

 pressure upon a nerve, cerebral or spinal sclerosis, small aneurisms 

 in the brain, etc. Choreic symptoms have been produced by injecting 

 granules of starch into the arteries entering the brain. Epilepsy and 

 other forms of convulsions simulate chorea in appearance. 



Stringhalt is by some termed "chorea." This is manifested by a 

 sudden jerking up of one or both hind legs when the animal is 

 walking. This symptom may be very slight in some horses, but has 

 a tendency to increase with age. In some the catching up of the 

 affected leg is very violent, and when it is lowered to the ground the 

 motion is equally sudden and forcible, striking the foot to the ground 

 like a pile driver. Very rarely chorea may be found to affect one of 

 the fore legs, or the muscles of one side of the neck or the upper 

 part of the neck. Involuntary jerking of the muscles of the hip or 

 thigh is seen occasionally, and is termed "shivering" by horsemen. 



Chorea is often associated with a nervous disposition, and is not 

 so frequent in animals with a sluggish temperament. The involun- 

 tary muscular contractions cause no i)ain, and do not appear to \)vo- 

 duce much exhaustion of the aflecteil muscles, although the jerking 

 may be regidar and persistent whenever the animal is in motion. 



Treatm-cnt. — In a few cases, early in the appearance of this affec- 

 tion, general nerve tonics may be of benefit, viz, iodid of iron, 1 

 dram: pulverized nux vomica, 1 dram; pulverized Scutellaria (skull- 

 cap), 1 ounce. Mix and give in the feed once a day for two weeks. 

 Arsenic in the form of Fowler's solution is often beneficial. If the 

 cause is connected with organic brain lesions, treatment is ustuilly 

 unsuccessfid. 



