Slight cases of functional disturbance may improve under good hygiene, open air life and tonics, cases due to poisons may recover spontaneously when such poisons have been eliminated, but those which depend on structural disorder of the brain are beyond remedy.
DISEASES OF THE SKIN.
Ultimate skin lesions in man and animals similar. Masked by thick cuticle, pigment, hair, fur, feathers. White, hairless skin. Lesions and deranged functions: Maculæ, erythema, papules, nodules, blisters, blebs, pustules, boils, carbuncles, scales, crusts, sitfasts, horny growths, erosions, abrasions, chaps, fissures, ulcers, excrescences, cicatrices, neuroses, morbid secretions, changes in glands, hairs, in derma. Scleroderma. Elephantiasis. Vegetable and animal parasites.
In cutaneous diseases in man and animals the actual lesions are largely of the same nature, yet in the animal covered with hair, fur or feathers, and with the cuticle deeply pigmented, the diagnosis of the different affections becomes much more difficult. On white-skinned animals and on parts with little or no hair, the identification of the different forms is usually possible. The following list may serve to indicate the nature of the different lesions, but these must not be accepted as indicating distinct diseases, as two or more of these forms often coexist or succeed each other in the same affection:—
1st. Maculæ: Spots: Discolorations. Examples: Black, melanotic spots in skins of white horses: white spots in dourine, after pustules, etc.: ecchymosis after contusions, stings, insect bites, etc.: petechial spots in anthrax, rouget, hog cholera, rinderpest, canine distemper, swine plague, scurvy, etc.
2d. Erythema: Rash: Flush. Congestive redness usually disappearing under pressure. Physiological in blush or glow of exercise, pathological from insolation, friction, deranged innervation, etc.
3d. Papulæ: Papules: Pimples. Small, red, hard, conical elevations, not forming blister nor pustule. Due to exudation and the accumulation of leucocytes at given points, having a local or general cause, (psoriasis, intertrigo, etc.).
4th. Tuberculæ: Nodules. Larger but still circumscribed thickening of the entire skin from exudation and cell growth, from ½ inch to 2 or more inches in diameter and sometimes becoming confluent. Examples: Urticaria (surfeit) in solipeds, and cattle; petechial fever, farcy, etc. Sometimes chronic.
5th. Vesiculæ: Blisters. Rounded or conical elevations the size of a millet seed to a pea, and having a small liquid exudation under the cuticle in the centre. In inflammations of the papillary layer, of a sufficiently acute type the tendency is to the formation of vesicles. These lesions are, therefore, often present in very different forms of skin disease from those due to simple thermic irritation, to constitutional diseases like eczema, or contagious ones like sheep pox. May merge into pustules or other advanced lesions.
6th. Phlyctenæ: Bullæ: Blebs. In these the individual lesion is larger than in vesicles. They are of any size from a pea upward. The most striking example is in cantharides, blisters, scalds and burns, but in other cases it depends on a constitutional condition or a specially exudative dermatitis.