Vertigo. Megrims. Blind Staggers. 77 



in spring, in a fleshy or fat horse, over- fed and little exercised, 

 when there is dark red congestion of the nasal mucosa and con- 

 junctiva, and a subsidence with rest. 



In the vertigo of brain lesions, the acute forms are attended by 

 fever and marked signs of delirium or disordered nervous func- 

 tions, while in the chronic forms there may be permanent hyper- 

 sesthesia, or anaesthesia, general or with rather diffuse limits, and 

 the vertiginous attacks repeat themselves frequently irrespective 

 of weather, though they may be precipitated by faults of feeding, 

 indigestion, severe exertion, or some of the other exciting causes 

 above mentioned. 



These cases are to be distinguished from epilepsy by the ab- 

 sence of any spasmodic contraction, aside from the jerking of the 

 head and rolling of the eyes, and by the fact that consciousness is 

 retained throughout. During the attack the animal may fail to 

 respond to irritation of the nasal mucosa, but this appears to be 

 due to the fact that his whole attention is engaged with a more 

 serious trouble. 



The duration of an attack is from one to two, or exceptionally 

 five minutes. The form which is represented by jerking of the 

 head and deviation from the direct line of motion may continue 

 so long as exercise is kept up. 



In the nasal vertigo of sheep and dogs, due to parasites, 

 sneezing, and congestion of the mucosa are to be looked for. 



In the cerebral parasitic vertigo of sheep and pigs, the 

 symptoms vary according to the seat of the parasite. These may 

 be blindness, turning in a circle, moving straight ahead regard- 

 less of obstacles, jerking upward of the head with nose protruded, 

 hemiplegia, hemiansesthesia, cross hemiplegia, cross hemianses- 

 thesia, and any one of the many forms of paralysis, or exagge- 

 rated nervous action. The animal usually turns to the side on 

 which the parasite lies and is paralyzed on the opposite side of 

 the trunk. A peculiarity of thes^ cases is that while the symp- 

 toms are continuous, yet .there are periodic aggravations which 

 bear no relation to feeding, exertion or excitement, but depend 

 on the protrusion at intervals of the heads of the parasites into 

 the brain substance. If there are several parasites in the brain 

 and they do this at different times the symptoms are liable to 

 vary according to their seat, and the special organ which is irri- 



