Megrims is a disturbed condition of the circulation of blood in the brain, which causes the horse to show signs of giddiness or stupor. This is usually manifested when the horse is at work, generally only a short time, and especially when the pace is fast, particularly in harness. The horse commences to shake his head, as if something had got into his ears; then he becomes unsteady in his gait, carries his head high, and, if not immediately stopped, will stagger about and fall. When on the ground he will lie a few minutes quite still, then get up, look stupefied and depressed, shake himself, and gradually regain his ordinary condition. From the fact that the attack usually comes on when the horse is driving in harness, it may be due to a badly-fitting bridle or collar, or a tight bearing-rein. It may also be due to over-feeding, or being put to work too soon after a hearty meal. But in many cases it is doubtless due to a diseased condition of the brain.
The treatment here, again, must depend upon the cause, which should, if possible, be removed. When it is due to a diseased brain, the horse should either be disposed of or destroyed, as dangerous accidents may arise when working him. When the horse is about to have an attack - shown by shaking and jerking about the head - he ought to be stopped at once, and some one placed at his head until he is calm. If he falls, the throat-strap should be unbuckled, the collar eased off the lower part of the neck, and cold water dashed on the head.