446 DISEASES OF THE SPINAL CORD 



Pathogenesis.— As soon as the injury occurs, and the cord 

 either crushed or compressed by extravasated blood or 

 serum, it loses its conductivity in proportion to the degree 

 of the injury and compression. The conductivity of the 

 cord may thus be either partially or entirely lost and the 

 function of the nerves will be partially or completely 

 destroyed in the area involved. In minor injuries with 

 simply edema of the membranes or cord the development 

 is gradual and the degree of involvement very slight. 



Symptoms.— The symptoms of compression or injury to 

 the spinal cord will depend upon: (a) The location of the 

 injury or portion of the cord affected; (b) the degree of 

 compression or destruction of the cord. When the spinal 

 cord is compressed or crushed in the cervical region the 

 animal, as a rule, does not live over a few minutes or hours. 

 Complete paralysis is observed posterior to the point of 

 injury. The patient may be able to bring the muscles of 

 the head into action for a short period preceding death. 

 In cases of lesser injury or compression the symptoms are 

 not so pronounced and the patient may be able to move 

 certain groups of muscles. If the compression is due to 

 edema of the membranes or hemorrhage into the cord or 

 canal the symptoms are milder and gradually disappear 

 in the course of a few days or weeks. 



Complete destruction of the cord posterior to the cervical 

 enlargement will produce paralysis and complete loss in 

 sensation in the limbs, tail and body. This is noticeable 

 in the respiration as the ribs remain fixed and the respiratory 

 movements are confined to the diaphragm. 



There may be retention of urine and feces, or they may 

 be voided involuntarily. 



When the dorsal portion of the spinal cord is affected 

 there will be paralysis of the posterior part of the body. 

 In slight injury or compression there may be only inco- 

 ordination of movement from the point of injury. 



Compression or destruction of the anterior part of the 

 lumbar segment results in paralysis and anesthesia of the 

 hind limbs, tail and muscles of the croup. When the 

 injury is in the middle or posterior portion of the lumbar 



