A non-poisonous ointment may be made by taking 4 ounces of oil of turpentine, 6 ounces of flowers of sulphur, and 1 lb. of lard. Mix the ingredients at a gentle heat, and rub in well with the hands or with a brush, at the same time breaking the crusts. The simple sulphur ointment may be made of one part of sulphur and four parts of lard; one fourth part of mercurial ointment may be added. Few remedies are so useful as sulphur iodide, and it may well be given a trial on head scab.
In most countries this disease has been made the subject of special legislation.
PSOROPTIC MANGE—SHEEP SCAB.
This is probably the gravest form of mange. It was described by Cato the Censor in 160 B.C., by Virgil, Juvenal, Celsius, Columella, Pliny, Vegetius, etc. In 1787 Abildgaard first showed that psoroptic mange in sheep could be cured by simple external remedies, without internal medications. In 1809 Walz described the causes, nature, seat, and treatment of the disease.
Since then, the parasitic, contagious nature of mange or scabies has been more and more clearly recognised.
Causation. Experience and observation have long shown that the only cause is the presence of the Psoroptes communis (ovis). This disease is much more contagious than that just described. Psoroptic mange or scabies exclusively affects those portions of the body covered by the wool, and may for a long time remain unrecognised.
The parasite is visible to the naked eye, though most inspectors employ the microscope. The adult female is about ¹⁄₄₀ of an inch long and ¹⁄₆₀ of an inch broad; the male is ¹⁄₅₀ of an inch long and ¹⁄₈₀ of an inch broad. The mites are discovered more easily on a dark background, and if a portion of the wool and crusts is placed on black paper and exposed to the sun for a few minutes the parasites will generally be seen crawling about on the paper.
The disease is transmitted directly or indirectly by contact from diseased to healthy animals in the folds, fields, or sheep runs. One diseased sheep may contaminate an entire flock. The disease is extremely contagious, and may appear even within a week after exposure.
The parasites have exceptional vitality. It is generally stated that, kept at a moderate temperature on portions of scab, the adults may live from four to twenty days, but they will occasionally live much longer; cases are on record where they have lived three, four, or even six weeks when separated from sheep; if the atmosphere is dry they will generally die in about fifteen days; but death is often only apparent, for the mites may sometimes be revived by warmth and moisture even after six or eight weeks; the fecundated females are especially tenacious of life.
