764 Megrims. 



and by the other narcotics, as also by some poisonous plants 

 (Solaniim, Equisetum, Lolium temulentiim and reed, Phrag- 

 mites communis, etc.). 



Symptoms. Horses are attacked chiefly when at work. The 

 animal suddenly manifests a staggering, slackened or uncertain 

 gait or it suddenly stops, nodding or shaking the head, snorting 

 conspicuously, pulls back in its harness, leaning against the 

 pole or the neighboring horse, after stopping they spread the 

 feet apart, the head is held sideways, the horse sways in the 

 direction of the inclined head, or presses with uplifted head 

 backwards or with sunken head forwards. These disturbances 

 of equilibrium sometimes last only a few seconds and the at- 

 tack is soon over so that after a short time the animal can con- 

 tinue its work. In other cases the animal completely loses its 

 equilibrium, loss of consciousness occurs and often also nystag- 

 mus, the animal collapses, falls (vertigo cadnca), and remains 

 for a long time lying quietly, then it commences to kick, suddenly 

 stands up, shakes itself and appears all right again. If the 

 attack occurs in the stable, the horse staggers to and fro with 

 outspread limbs, holds its head up or to one side, hangs on the 

 halter strap, or leans against the partition or wall and suddenly 

 falls to the ground. The course of vertigo runs similarly in the 

 other species of animals. 



At the beginning of an attack the animal shows great anx- 

 iety, its gaze is fixed, the pupils are dilated, respirations are 

 quickened and sweating is general all over the body. Dogs fre- 

 quently vomit and at times urinate and defecate involuntarily. 



Individual attacks last barely for one or two, exceptionally 

 up to five minutes, but recur at varying intervals of time. Horses 

 that are subject to vertigo are most frequently attacked during 

 work and in warm weather, whilst in winter they are seldom 

 affected. When being led or ridden, horses subject to vertigo 

 are seldom attacked. 



The name vertigo abdominalis was formerly applied to a disease i)ecidiar to 

 horses. Its symptoms on the one hand were severe tligestive disturbance (diminished 

 appetite, colic, tympanitis) and on the other great dullness and possibly also forced 

 movements and great excitement. Such attacks were repeated, and finally after some 

 hours or days the patient recovered or at times died. It is very probable that this 

 affection was due to poisoning by plants. 



Seasickness causing a dizzy feeling is occasionally seen in animals. Damoiseau 

 saw it in an Arab horse transported from Syria to France. On the first day, the 

 animal was depressed, alternately bending and stretching his head, neighing often, 

 trembling all over his body and vomiting after each feed for four days ; in eight days 

 he had recovered. Bering has repeatedly seen the same illness in dogs. 



Diagnosis. Vertigo may at all times be mistaken for epi- 

 lepsy; it is differentiated, however, from this affection by the 

 absence of convulsions. Restiveness and fright are scarcely 

 noticeable since in these the disturbances of equilibrium are 



