ocular or aural trouble; during attack, stop in shade, cold to head, deplete, bleed, purge, shady pasture or light work, bromides, blisters, etc. In dealing with vertigo or giddiness in animals we are confronted by the impossibility of realizing the subjective feelings of the animal, as we can so easily ascertain by interrogation in the case of man, and thus our conclusions are largely inferences drawn from certain unsteady, reckless or uncontrollable movements, or from an apparent inability to maintain a stable equilibrium. The condition is rather a symptom of a variety of morbid conditions, functional and structural, than a disease _sui generis_. It may be due to alcoholic or other narcotic intoxication, to overloaded or otherwise deranged stomach, to shock, to a stroke of lightning, to disturbances—anæmic or hyperæmic—in the circulation in the encephalon, to degenerations, parasites or tumors in the brain, to compression of the jugular veins, to valvular or other disease of the heart, to disease of the internal ear, to the plethora of spring or early summer, to the qualms of sea sickness, to insolation. The purely toxic cases are more clearly defined and temporary so that they may be eliminated from consideration at present, yet their possible occurrence must always be borne in mind by the practitioner especially when called to pronounce upon cases of vertigo in connection with veterinary legal questions. The cases that are due to a persistent neurosis, or to circulatory troubles may well be placed in a list by themselves, yet in their legal relations it is highly important that the practitioner should as far as possible discriminate among these as well. _Susceptible Animals._ Vertigo undoubtedly exists among all domestic animals. The symptoms by which it is recognized have been noted especially in the horse and much less frequently in ox, dog, pig and sheep. Among _horses_ it especially attacks the mature or aged, and family harness horses, pampered and irregularly exercised; (saddle 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 appear in the absence of these. _Causes._ 1st. =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 complete 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.