178 DISEASES OF THE NERVOUS SYSTEM. 



<Pti<R&LYSIS. 



Paralysis is a symptom, not a disease. It is characterized by impair- 

 ment o'r loss of muscular contraction whilst the power of making an 

 effort of the will remains. It may he partial, confined to one or more 

 muscles; or the muscular system may he involved. 



Paralysis may arise from diseases of the great nerve centres, the hrain 

 and the spinal cord ; it may be due to certain influences which diminish 

 or destroy the integrity of the nerves themselves ; it may result from a 

 diminution or loss of excitability and contractility of the muscles. 



Causation . —Contusions, wounds, fractures, and other injuries produced 

 traumatic ally. Diseases of the parts in the region of the nerves, thereby 

 causing compression, as in the case of tumors, enlarged glands, and many 

 other conditions. 



Diseases of the brain and spinal cord are amongst the most frequent 

 causes of paralysis. Disturbances in circulation as in a clot plugging an 

 important artery in the brain, thereby cutting off the supply of blood 

 from a portion of it. Certain poisons are known to produce paralysis. 

 The affection in some instances occurs after acute diseases; it appears in 

 exhaustion of the nervous system. 



In dogs is often observed the so-called reflex paralysis, occurring in 

 consequence of some disease, injury, or irritation, existing at points of 

 nerve distribution, as in intestinal disorders and affections of the kidneys, 

 bladder, etc. Worms, constipation, and contusions not uncommonly cause 

 an impairment or loss of power in the hind parts. 



Symptoms . —If paralysis is partial it is shown by a trembling, feeble- 

 ness, and uncertainty of the movements of the parts affected. If complete, 

 the muscles are more often relaxed and incapable of the slightest resist- 

 ance. In spinal paralysis the uniform affection of both sides is the more 

 common feature. When the brain is the seat of the disease, loss of power 

 almost always occurs on one, and the opposite side of the head or body. 

 When the affection is reflex, the impairment or loss is limited to the region 

 supplied by one or a few nerve trunks. 



The disease may come on suddenly or gradually. After existing for a 

 time the muscles lose their contractility, waste, and power of motion in 

 them is permanently destroyed, or the affected nerves may change, become 

 incapable of conducting impressions, and thus recovery is impossible. 



Treatment. — In cases of paralysis occurring suddenly, the bowels 

 should be moved freely, and the ability of the animal to void his urine be 

 determined by watching. If the bladder is involved by the disease it 

 must be emptied by a catheter. It is of the greatest importance that the 

 cause be determined and treatment directed to its removal. 



