The virus is most conveniently taken direct from the affected sheep, but it may be preserved in capillary tubes, or on glass or ivory points, or mixed with glycerine between glass plates, or finally, the first scab well dried may be preserved and utilized, a minute portion being inserted with the lancet in a pocket made under the epidermis.
Attempts have been made to secure a mitigated and safer virus, by diluting the lymph with water or normal salt solution (1:50–150) (Peuch), by amputating the seat of inoculation (the tip of the ear) on the 4th or 7th day, when the vesicle is formed (Galtier), by taking a susceptible sheep and inoculating it with sheeppox virus for ten consecutive days, and then selecting for use the lymph from the papule of the sixth inoculation. The inoculations of the seventh day and later give rise to no papule even (Pourquier). By this means it is claimed that the inoculated disease remains strictly local, passes through its successive stages in a shorter time (15 days or less), and is perfectly harmless to the sheep inoculated. Nocard and Mollereau sought the same end by mixing the virus with oxygenated water, and Semmer and Raupach by heating it to 130° F. In view of the facts that it is only under extraordinary conditions that ovination is permissible at all, and that the mortality, resulting from it can be kept down to about 1 per cent., it seems hardly worth while to attempt to obviate this loss, by any method which may come short of the full measure of immunity.
Ovination confers immunity for a year or longer.
The care of the flock during eruption is the same as in sheeppox contracted in the usual way.
SHEEPPOX IN GOAT. VARIOLA CAPRINA.
The goat can be successfully inoculated from the sheep, the resulting vesicles being smaller and less prominent, and the disease assuming a milder type. It is alleged to pass naturally from sheep to goat, and from goat to sheep, as well as from goat to goat but, on the whole, it is a rare disease and goats have been known to live in flocks of sheep attacked with sheeppox, without themselves contracting the disease. The malady seems to be of little account to the goat, yet in sheep countries, the interests of flockmasters would demand that it should be stamped out as vigorously as the same disease in sheep.
GOATPOX; VARIOLA CAPRINA.
In Persia according to Bruce goats suffer from a form of variola, having larger vesicles, umbilicated and approximating to, if not identical with cowpox. In Algiers there is found a goatpox from which sheep are alleged to be immune (Nocard, Peuch, Bremond, Galtier) so that further observations are wanted to put the different forms of variola of the goat in their proper places. In a country where sheeppox is constantly present, there is of course the possible source of fallacy of experimenting with animals that have already had the disease, therefore it would be expedient to put all forms of goat variola under police control.
SWINEPOX. VARIOLA SUILLA.
Variola appears to be rather more frequent in swine than in goats. Ficanus as quoted by Joubert saw it in 1567, contracted it was supposed from smallpox patients. It was noted by Ramazini in 1690, by Stegman in 1697, and later by Gerlach and others. In 1891 517 cases were reported in Hungary. It is said to be derived from man by the use of bed straw for litter and from sheep by occupying the same stall. It can be transmitted experimentally from pig to pig, from pigs to goats, and from goats back to pigs (Gerlach). It is also claimed to pass from the pig to man (Freidberger and Fröhner). Young pigs are especially subject to it and one attack confers immunity for the future.