England to Africa, on white skins, especially of face. Symptoms: local congestion, swelling, itching, desquamation, during extreme heat: in worst cases fever, dullness, inappetence, costiveness, diarrhœa, head constantly moving, rubbing, vesicles, pustules, excoriations, cracks, fissures, septic ulcers in nose and mouth, submaxillary and pharyngeal swellings, recovery with dermal thickening and tenderness. Diagnosed from petechial fever by the itching, and the absence of petechiæ. Prevention: breed solid dark colors, avoid white skinned in hot climates or work in shade, away from hot winds; sunshade; avoid friction and wetting in sunshine. Treatment: shade, astringents, cool irrigation, vaseline, zinc ointment, lamp black, antiseptics. Tie so as to prevent rubbing.
This has been observed in different latitudes from the cool climate of Great Britain, to the burning suns of Africa, though it reaches its highest intensity in the hotter regions. The parts to suffer are those that are devoid of pigment, as the white star, snip or blaze on the face, the white feet or legs, the white areas in the piebald, and the whole surface in the albino. The white face, however, suffers more than the white legs, apparently because of its more constant exposure, the absence of shadow from the trunk, and the delicacy of the skin and fineness and thinness of the hair.
Symptoms. In slight cases there may be no constitutional disorder, only redness, itching, swelling and subsequent desquamation of epidermis on the white portion of the skin, which may prove persistent so long as hot weather lasts and recover on the advent of cold.
The more violent cases seen in warmer climes, may be heralded by febrile reaction, dullness, prostration, inappetence, constipation and sometimes diarrhœa. The head may be kept in constant movement, the itchy white parts being rubbed on any object within reach, and the limbs are stretched, the front ones forward and the hind backward, with a tendency to rub them with the nose or foot. The skin at first red, becomes later swollen, covered with vesicles which pass into pustules, burst and discharge. Meanwhile the subcutaneous connective tissue is infiltrated and gravitates toward the lowest parts, causing extensive submaxillary swellings and stocking of the limbs. In its worst forms it may go on to necrosis and sloughing, but more commonly the affected part becomes raw, excoriated, cracked and fissured. Sometimes the pituita or even the buccal membrane becomes involved, with muco-purulent discharge. In other cases the absorption of septic products causes inflammation and swelling of the submaxillary or pharyngeal lymph glands. Under favorable conditions, the secretions dry, the sores heal and the exudate is in great part absorbed, but there usually remains some thickening of the affected parts and a diminished vitality of the skin, which renders it morbidly sensitive to sources of irritation.
Severe cases might be mistaken for petechial fever, but there is much more pruritus, and there is an absence of the petechiæ, on the mucosæ, and of a tendency to the extension of the disease far beyond the patches of white.
Treatment. Prevention. This malady should be warded off by breeding or selecting for warm, sunny climes, animals of a solid color, and discarding all with white patches. Animals bred in a cooler climate should not be suddenly transferred to a hot one. When the animal with white face or feet is found in the hot sunny climate, it should be devoted as far as possible to work in the shade (indoors or in mines), or its white patches should be protected against the full unmitigated rays of the sun, and the hot winds. Sun shades are useful or in their absence leafy branches fastened to the bridle so as to protect the face. It is further important to avoid the friction of harness on the susceptible parts, or wetting of them when in the full glare of sunshine. Another obvious precaution is to keep the white patches well covered with lamp black.
When attacked the animal must be placed under cover and eruption treated with cooling astringents, constant irrigation with cool water, or lotions with acetate of lead, tannic acid, alum or sulphate of zinc. When the skin is dry and rigid it may be treated with vaseline, alone or with zinc oxide, lamp black or any one of the astringents above named. Open sores may be treated like ordinary wounds, tense engorgements may be drained by punctures followed by antiseptic dressings, and abscesses may be opened and evacuated.
During the treatment the patient should be tied short to two sides of the stall, and other measures taken to prevent him from rubbing or otherwise injuring the affected parts.