It is to be observed that the parasite has more difficulty in living on robust and well-nourished animals. Moreover, observation shows that transference from poor land to rich pastures is sometimes in itself sufficient to bring about a spontaneous cure. Such, at least, is the belief of the Spanish sheep farmers in Estramadura and of the French shepherds.
The shepherd can do a great deal to arrest the course of the disease. If he is careful, zealous, intelligent and observant he will quickly note the first indications of the disease and, by isolating the animals, check its spread.
The second point consists in shearing the diseased animals, and this must be carried out at any season of the year. The money loss is sometimes important, but must be met, for otherwise treatment is impossible. In cases of localised scab, empyreumatic oil, oil of cade, solutions of sulphuret of potassium, decoctions of black hellebore (water 1 quart, fresh rhizome 4 ounces or dry rhizome 2 ounces), decoction of tobacco and diluted tobacco juice (6 ounces in 1 quart of water) have been recommended. Such local treatment, however, is often useless, because incomplete.
When scab is generalised and it is impossible to define the parts attacked, general treatment is indispensable and the diseased sheep should be dipped.
As a preliminary, however, and in order to make sure that the application will produce its effect, the animals after shearing should be passed, twenty-four hours before the medicinal bath, through a warm bath containing soap in order to soften and remove the scabs. Applications of oil or some fatty substance will also soften the scabs, which may afterwards be removed with a scraper without producing bleeding. One pound of soft soap may be dissolved in fifty quarts of water and each sheep plunged into this and scrubbed with a brush for a few minutes. Washing alone removes a large number of the parasites.
Whatever bath be used it should not be given until four or five hours after the last feeding. The dips most popular in France are as follows:—
Tessier’s Bath (1810).
| For 100 sheep | Arsenious acid | 1½ | parts or lbs. |
| Sulphate of iron | 10 | „ | |
| Water | 100 | „ |
The above materials should be boiled for ten minutes, and, as a consequence of the chemical fusion which occurs in the process, the proportion of arsenious acid dissolved amounts to about 2 drachms per quart instead of 3¾ drachms.
In this bath the arsenious acid acts as a parasiticide and the sulphate of iron as an astringent, the latter checking the absorption of toxic principles by the skin and sores, and preventing the sheep from licking themselves.