DISEASES OF THE NERVOUS SYSTEM. . 233 



twice a day. To strengthen the system, iodid of iron 1 dram twice a 

 day and 1 dram of nux vomica once a day may be given in the feed. 

 Electricity to the paralyzed and weakened muscles is advisable; the 

 current should be weak, but be continued for half an hour two or 

 three times daily. If the disease is due to a broken back, caries of 

 the vertebrae, or some other irremediable cause, the animal should be 

 destroyed at once. 



MYELITIS, OR INFLAMMATION OF THE SUBSTANCE OF THE 



SPINAL CORD. 



This is a rare disease, except as a secondary result of spinal menin- 

 gitis or injuries to the spine. Poisoning by lead, arsenic, mercury, 

 phosphorus, carbonic-acid gas, etc., has been known to produce it. 

 Myelitis may be confined to a small spot in the cord or may involve 

 the whole for a variable distance. It may lead to softening abscess 

 or degeneration. 



Symptoms. — rThe attack may begin with a chill or convulsion ; the 

 muscles twitch or become cramped very early in the disease, and the 

 bladder usually is affected at the outset, in which there may be either 

 retention or incontinence of urine. These conditions are followed by 

 complete or partial paralysis of the muscles posterior to the locality 

 of the inflamed cord, and the muscles begin to waste away rapidly. 

 The paralyzed limb becomes cold and dry, due to the suspension of 

 proper circulation; the joints may swell and become edematous; 

 vesicular eruptions appear on the skin; and frequently gangrenous 

 sloughs form on the paralyzed parts. It is exceedingly seldom that 

 recovery takes place. In a few instances it may assume a chronic 

 type, when all the symptoms become mitigated, and thus continue 

 for some time, until septicemia, pyemia, or exhaustion causes death. 



Pathology. — The inflammation may involve nearly the whole 

 length of the cord, but generally it is more intense in some places 

 than others; when due to mechanical injury, the inflammation may 

 remain confined to a small section. The cord is swollen and con- 

 gested, reddened, often softened and infiltrated with pus cells, and 

 the nerve elements are degenerated. 



Treatment. — Similar to that of spinal meningitis. 



SPINAL CONGESTION. 



This condition consists in an excess of blood. As the blood vessels 

 of the pia mater are the principal source of supply to the spinal 

 cord, hyperemia of the cord and of the meninges usually go together. 

 The symptoms are, therefore, closely allied to those of spinal menin- 

 gitis and congestion. When the pia mater is diseased, the spinal 

 cord is almost invariably affected also. 



