This section is from the book "The Stable Book: Being A Treatise On The Management Of Horses", by John Stewart. Also available from Amazon: The Stable Book.
Wet cold weather always produces emaciation and a long coat. If the horse be put out without preparation, he is apt to have an attack of inflamed lungs, a sore throat, or a common cold, with discharge from the nose. He may sicken and die. Many people seem to think no usage too bad for the horse, if it do not immediately produce some deadly disease; that is to say, they do not car6 for consequences, unless they are sure their interest will be materially affected. A fool will often sacrifice his interest to a certain extent, rather than be guilty of kindness to his horse, or give himself any trouble. He may know that cold will make the beast lean for certain, and that it will cost so much grain to restore his flesh; and he may know that sickness may arise from sudden exposure; but that is only probable, and he incurs the risk rather than take the trouble of putting his horse under cover when a wet night or a cold day comes. Early in spring, or late in autumn, he is turned out of a warm comfortable stable, and left to battle with the weather as he best can.
He crouches to the side of a hedge, shivering and neglected, as if he had no friend in the world; and of all who pass him, no one seems to think he is suffering any hardship, while those who have imbibed the "manly bravery of British subjects" consider him a fair mark for a stone or a jest.
In time, the horse becomes inured to the weather, if he do not sink under it. But sometimes he comes home with diseased lungs, and very often with a cough which never leaves him, and which produces broken wind.
Shelter is too much neglected, especially in winter pastures. It is easily provided, at the cost of a few rude boards. A hovel, covered on three sides, the fourth open to the south, and just high enough to admit the horse, will answer the purpose. The bottom should be sloping, elevated, and quite dry. When litter can be afforded, it will tempt the horse out of the blast. There may be hay-racks and mangers, strong, though of rude construction. In summer the horse can retire here during the heat of the day, and in winter he can avoid the storm of slow or rain.
Exposure to hot weather is not so pernicious, yet it always produces pain, if the horse be turned out in the middle of summer. For a while he is fevered all day and loses flesh; but he soon recovers. The parts that are most apt to suffer are the brain and the eyes. Staggers, that is, an affection of the brain, is not common, and the eyes never suffer permanent mischief. They are inflamed by the flies, but the brain is injured, partly by the heat, and partly by the pendent position of the head, aided perhaps by plethora.
 
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