1 62 Veterinary Medicine. 



posure to cold draughts when heated, or excited, by plunging 

 into ice cold water, by lying on cold, damp, stone pavement or 

 metallic plates. Violent over-exertion, excessive fatigue, and a 

 variety of traumatisms are further factors. Kicks, blows on the 

 back, concussion from falling from a window or other height, 

 and sprains received in fighting or otherwise, are common causes. 

 Disease of the vertebrae or abscesses in their vicinity will some- 

 times extend to the meninges and cord. 



Lesions. These are like those in the larger animals, being to a 

 large extent determined by the cause and nature of the lesion, 

 concussion, sprain, fracture, pysemic, septicaemic, or other in- 

 fection. Tile implication of the myel to the exclusion of the 

 meninges is very frequent and the lumbar enlargement is the 

 most common seat of disease. Localization in the brachial en- 

 largement or in one lateral half of the cord is unconunon. The 

 gray matter towards the extremity of the horn is the most com- 

 monly involved, reflecting a yellowish, grayish red or deep red 

 color, and breaking down into a pultaceous mass on the slightest 

 pressure. At an advanced stage the altered coloring matter 

 gives to the tissue a brownish yellow color without altering its 

 consistency. The still vital and vascular area around the centre 

 of softening may be slightly swollen and abnormally firm. The 

 neuroglia is the seat of leucocytosis, and minute (usually puncti- 

 form) extravasations of blood. The red globules are crenated 

 or otherwise distorted and the white are granular and opaque. 

 The neurons are swollen, granular and opaque and the nerve 

 fibres are more or less diffluent, moniliform and in their sub- 

 stance show no clear outline of white substance and axis cylin- 

 der. Interruptions by granule masses and vacuoles are common. 

 In old standing or chronic cases the liquid exudate and granular 

 debris have been largely absorbed and the thickening of the 

 neuroglia by fibrous neoplasm, has restored the firmness or even 

 approximated the part to a condition of sclerosis. 



In case the meninges are involved there is thickening by exud- 

 ation into their substance or on their surface, there may be ad- 

 hesion between the outer and inner layers of the arachnoid and a 

 serous fluid, red, milky or clear, distends the arachnoid or sub- 

 arachnoid space. The false membranes, here as elsewhere, are 

 usually red if recent, and increase in pallor with age. 



