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.
BUCKWHEAT ERYTHEMA: FAGOPYRISM. WHITE SKIN DISEASE.
Form of white face disease, with irritating ingesta, buckwheat, etc., occurs from dried products, no insects; growing potatoes; sunshine; idiosyncrasy. Symptoms: as in white face disease: in winter itching and rubbing: in summer may go on to nervous symptoms. Treatment: stop feeding buckwheat. Give laxative and diuretics. Local treatment as in white face disease.
This may be held to be but a form of the last named affection, in which, however, certain irritating ingesta (buckwheat, maize, wheat), are essential factors in addition to the white skin and strong sunshine. It is seen only on white skins or the white portions of parti-colored skins, while the blacks, browns and other colors usually escape. Black breeds of hogs (Essex) escape under the same feeding and exposure, as do solid colored horses of the darker shades. Of the different food factors, buckwheat (Polygonum fagopyrum, persicare, etc.), is the most to be feared, and the poison seems to be inherent in all the products (green vegetable, dry seeds, bran and straw) and is not destroyed by cooking. Buckwheat cakes sometime produce erythema in man. This excludes the idea of the transfer of a living cryptogam to the skin, though not the theory of pathogenic products of the fungi. The invoking of bee stings and the bites of insects, which are strongly attracted to the buckwheat, is untenable because the affection occurs from the dried seeds, bran and straw, and has been known to break out weeks after the buckwheat was withdrawn from the ration.
In addition to buckwheat, maize and even wheat when liberally fed have been known to cause erythema. Hemminger records a similar outbreak in horses working among growing potatoes.
In addition to the food, clear sunshine is essential and an individual idiosyncrasy. All animals, though equally exposed are not equally attacked.
Symptoms. These do not differ materially from those of the white face and foot disease already described. There are intense redness and tumefaction of the white skin or the white portions, showing prominently in the delicate parts (ears, eyelids, lips), with violent itching, rubbing and sometimes vesicles with yellowish contents, followed by sores and scabs. In the winter season there may be itching and rubbing only. In summer it may become erysipelatoid and extend to the mucosæ, of the respiratory and digestive organs, with hyperthermia, nervous excitement, vertigo, turning in a circle and even spasms and convulsions.