416 HEALTH AND DISEASE 



too freely uphill when the pressure of the collar is increased, or driven 

 in face of a hot sun. The frequent occurrence of these symptoms in the 

 early spring and during the summer is mainly on account of exposure to 

 the last-named cause. 



The attack comes on without warning. The animal stops and suddenly 

 falls to the ground, the muscles quiver or are rigidly set, the eyes roll, 

 there is loss of consciousness, and for a time also of feeling and muscular 

 power. After a brief period the stricken beast regains his lost powers 

 and is able to rise, but for several days he remains dull, feeble, and 

 stupid, .and altogether unfitted for work. In other cases the animal hangs 

 his head, and presents an expression of drowsiness and an indisposition 

 to move. In less severe attacks he will suddenly stop while being driven, 

 lay back his ears, shake his head violently, or throw it up and down 

 without any obvious reason, and in a few minutes resume his journey 

 as if nothing had happened. 



In the more severe attacks the patient is stricken down paralysed and 

 unconscious and quickly succumbs. 



Treatment in these cases is of no avail, and although something may 

 be done to ward off the attacks by a judicious system of general manage- 

 ment and feeding, horses affected with brain tumours are dangerous beasts 

 to possess, and should be destroyed. 



(EDEMA OF THE CHOROID PLEXUS 



This is a condition in which the choroid plexuses of the ventricles are 

 infiltrated with fluid which has escaped from the fine net-work of veins of 

 which they are mainly composed. So far as is known it is of somewhat 

 rare occurrence. It may, however, be more common than is generally 

 supposed, were post-mortem examinations more frequently made of 

 the brain in those cases where death follows upon sudden and complete 

 coma. 



The causes of oedema of the choroid plexuses is not well established, 

 but in the case of which an illustration is here given (see Coloured Plate) 

 the horse had been the subject of influenza, and appeared to be making a 

 good recovery. He was, however, suddenly seized with dulness, followed 

 by deep coma, and death occurred twenty-four hours later. 



Post-mortem examination showed clots of coagulated blood obstructing 

 the veins leading from the plexuses into the veins of Galen. 



There was nothing either in the history of the case, or in the post- 

 mortem inspection, to show why the blood should have clotted and 

 obstructed the circulation in these veins. A blow on the head in such 



