564 NERVOUS DISEASES. 



extremities. If an attempt is made to back the horse, great 

 difficulty is experienced and, in some cases, it is impossible. The 

 hind feet are not raised from the ground, the back is arched, and 

 the muscles of the quarters are rendered rigid or convulsed in a 

 way well described as trembling or shivering. When turned 

 sharply, the hind legs move in a jerky, uncontrolled manner. 

 When startled or backed, the tail is spasmodically elevated, and 

 this, perhaps, is as marked a peculiarity as any other. If an 

 attempt is made to raise one of the hind feet, there is great diffi- 

 culty. If it be successful, the limb is snatched up, and the muscles 

 of the thigh and quarters show the spasmodic contractions, which 

 are very characteristic. Some shiverers show decided symptoms 

 when taken to a water trough, or when offered a pail of water on 

 the groimd. As soon as they extend the neck, the hind quarters 

 are seized with a spasm, and whilst the fore feet remain implanted 

 on the ground, the body is thrown backward, the back arched, and 

 the tail and quarter muscles convulsively shiver. Bad shiverers 

 have been seen that would face a water-trough without a sign. 

 Aggravation of, symptoms may accompany an attack of strangles or 

 influenza. Some of these cases present such acute symptoms of 

 oerebro-spinal disease as to cause the greatest alarm. There is great 

 constitutional disturbance, shown by pulse and respirations being 

 doubled in frequency. Partial paralysis of the hind extremities is 

 seen. Muscles of neck, back and quarters are rigid. Movement 

 either backwards or forwards is almost impossible, and the 

 countenance expresses fear and pain combined. As a rule, the 

 symptoms gradually subside, and the horse resumes work with no 

 inability save that shown when backed. 



In a few cases, the spasms appear in the fore limbs. Sometimes, 

 bad shiverers are subject to more or less severe paroxysms of 

 spasms, which may be complicated with distressed breathing, and 

 high temperature, and which pass off after a time, only to return 

 on future occasions. 



Paralysis, as in kumree (p. 542), is not a symptom of shivering. 



COURSE AND GRAVITY.— In almost all cases, shivering runs 

 a chronic course, is incurable, and gets worse with age. Hence, it 

 is an extremely grave unsoundness. Some bad shiverers work 

 fairly well between the shafts, but, as a rule, it is best to use them 

 in the plough, or as leaders, so as to avoid, as far as practicable, 

 straining them by backing and turning them. 



PREDISPOSITION AND CAUSES.— Hereditary predisposition 

 is undoubtedly a strong factor in the production of this disease. 

 It is not uncommon among the cart horse and vanner type of 



