632 Obstruction of the Vessels of the Braha. Encephalitis. 



symptoms, as the references to this kind of case are very sparing. It is 

 obvious that the local symptoms will depend upon the portion of the 

 brain affected ; and general symptoms will depend upon the local symp- 

 toms shown. As in hemorrhage of the brain, thrombosis or embolism of 

 the arteries is responsible for the sudden appearance of general symp- 

 toms of brain disease. These may disappear sooner or later, but they 

 may also be responsible for the death of the animal. In cases of throm- 

 bosis of the veins or venous sinuses symptoms make their appearance 

 more gradually as in encephalitis. 



In Boelmann's case a mare appeared to be dull and its gait was uncertain, 

 the head was drawn round towards the left side, and the animal moved in circles 

 in this direction. At a later stage the animal showed the following symptoms: 

 Paralysis of the left eyelid, partial closure of the left nostril, insensibility of the 

 left half of the head, dullness and later ulceration of the cornea of the left eye, 

 the lower jaw drawn towards the left. Eight days later the animal could no longer 

 stand and death occurred on the 24th day. At the postmortem an old thrombus 

 1.5 cm. in length was found in the vein of Galen at the point where it enters 

 the sagittal sinus, and another in the neighborhood of the corpus callosum. There 

 was softening of the entire left hemisphere but especially in the middle part. 



In a steer suffering from suppuration of the submaxillary gland Moussu ob- 

 served, two weeks after the commencement of the disease, increased excitability, 

 and eight days later symptoms of excitement alternating with dullness. At the 

 postmortem it was found that the suppuration had extended along the internal caro- 

 tid and thus reached the base of the brain, and caused inflammation of the venous 

 sinuses followed by thrombosis. 



A'osshage saw the following symptoms in a case in which there was throm- 

 bosis of the posterior cerebellar artery: Paralysis of the right side of the body, 

 staggering gait and paralysis of the left facial nerve. 



In a case in which there was diffuse calcification of the arteries of the brain 

 and membranes Huynen observed coma, elevation of the head, involuntary move- 

 ments and a staggering gait. The train of symptoms recalled sleepy staggers. 



Literature. Berlin, O. Vj., 1879, LI, 142.— Boelmann, Ann., 1885, 275 (Ref.). 

 —Huynen, ibid., 1907, 80.— Moussu, Eec, 1899, 313.— Schiitz, A. f. Tk., 1878, IV, 

 145.— Vosshage, D. t. W., 1902, 483. 



10. Encephalitis. 



The cause of encephalitis is usually of an infective nature 

 and the diseased areas are circumscribed. There may be centers 

 of suppuration (purulent encephalitis), or there may be non- 

 purulent areas which are red, yellow, or grayish in color and 

 have undergone a process of softening. In some cases there are 

 no areas of inflammation visible to the naked eye (acute non- 

 purulent encephalitis). 



It has already been pointed out that in cases of meningitis, the 

 inflammation of the membranes extends to the superficial layers of the 

 cortex, the reason being that the same blood-vessels are common to both. 

 In such cases the inflammation of the cortex is secondary, and as a rule, 

 makes its appearance in the later stages of meningitis. Besides cases of 

 this type, encephalitis occurs in the domesticated animals in which the 

 inflammation involves the cortex only, or if the pia mater in the im- 

 mediate neighborhood be involved it is only to the very slightest de- 

 gree. The inflammation of the brain substance is the principal lesion ; 

 and the meningitis is not responsible for any observable symptoms. 



Distinction between purulent and non-purulent encephalitis, is of 



