Vertigo. Megrims. Blind Staggers. 75 



9th. Nasal Vertigo has been noted hy Cadeac in connection 

 with irritation in the nose and especiall}' b}' the larva of oestrus 

 ovis (sheep), and the linguatula (dog, horse). In certain of the 

 cases manifested b}' jerking of the head and diverging to one 

 side, the recovery after section of the pes anserina indicates a 

 nasal origin. 



loth. Vertigo from Narcotics (alcohol, loliuni temulentum, 

 belladonna, solanum, various essential oils, carbon monoxide, 

 etc)., have been already referred to. 



nth. There remains to be noted cases in which no narcotic 

 poison, no mechanical disturbance of the circulation, no visual, 

 aural nor nasal trouble, no gastric nor hepatic disorder, and not 

 even a di.stant nervous lesion can be found ; the disease ma}- in 

 such cases be ranked for the present as essential vertigo. 



Symptoms. As usually seen in the horse, vertigo often attacks 

 the nervous, irritable animal in which the slightest occasion of 

 irritation or disturbance causes intense suffering and quick re- 

 sponse. This is often aggravated by the plethoric condition of 

 the animal, kept on a liberal ration of grain and having little 

 exercise. In some forms of the affection, however, and especial- 

 ly the gastric and hepatic, the subject is dull, carries the head 

 low, and lacks vivacity and energy. 



In the first form (the most common in the horse) the animal 

 which has been full of life and vigor, slackens his pace and the 

 tension on the reins, or stops suddenly, shakes the head, vertical- 

 ly or horizontall)', or jerks it to one side, trembles, staggers, 

 props his legs outward for more stable support, presses against 

 the pole, or the other horse, or a wall, leans on the breeching or 

 hangs on the breast strap, plunges forward, or to one side, or 

 rears up and even falls backward, and comes to the ground. 

 Profuse perspiration ensues, the eyes roll, the face is pinched and 

 drawn, the prostrate animal may struggle in a helpless waj', and, 

 if the harness is loosened, he may get up in a few seconds and 

 slowly recover. Often, however, he remains for an hour or 

 more, nervous, sensitive, bedewed with sweat, trembling and 

 with anxious expression. Such are the more common manifes- 

 tations of what is familiarly known as blind staggers. The 

 symptoms will vary however, with the cause. 



In gastric or hepatic cases there may be more particularlj^ 



