Vertigo. Megrims. Blind Staggers. 71 



Among horses it especially attacks the mature or aged, and 

 family harness horses, pampered and irregularly exercised ; (sad- 

 dle horses rarely suffer) ; it is more likely to appear for the first 

 time in spring though when established it happens at all seasons ; 

 it may come on when a horse is driven in blinders and fail to ap- 

 pear in the absence of these. ' 



Causes, ist. Compression of the jugular veins by a too tight 

 collar is the cause of one of the simplest forms of vertigo and is 

 observed, in growing or fattening animals in which the neck has 

 become gradually too large for the collar. The supply of a larger 

 and well fitting collar will soon confirm the diagnosis by a com- 

 plete and permanent removal of the trouble. In other cases the 

 veins may be compressed by undue flexion of the head, the chin 

 being drawn toward the breast, or by a throat latch buckled too 

 tightly. The substitution of an overdraw check rein, or a loose 

 throat latch will show the true source of the trouble. 



2nd. Disease of the valves of the heart or their insufficiency 

 from cardiac dilatation is a common cause of vertigo, and maybe 

 recognized by auscultation and by the general symptoms of 

 chronic heart disease. 



3d. Disease of the lungs interfering with the flow of blood 

 through the right heart and more distantly with the return of 

 blood from the brain. It further effects the brain functions 

 through the circulation of a highly carbonized blood, which fails 

 to maintain the normal functions of the ganglia. 



4th. Disease of the blood vessels, it may be by emboli 

 washed on from clots in the pulmonary veins or the left heart 

 and arrested in the vessels of the brain ; it may be by aneurism 

 of the anterior aorta as reported of a horse (lyUStig) ; it may be by 

 phlebitis and thrombosis of the jugulars ; it may be by adjacent 

 tumors pressing on the vessels. 



5th. Gastric Vertigo, Abdominal Vertigo, is a complica- 

 tion of gastric or hepatic disorder with giddiness and unsteady 

 movement. The abdominal disorder may be at once a cause and 

 result of the vertigo and it is not always easy to decide which 

 predominates. The unsteady movements in certain cases of over- 

 loaded stomach in the horse are illustrations of purely abdomi- 

 nal vertigo, while on the other hand in vomiting animals nausea, 

 retching, emesis, and other gastric disorders promptly attend on 



