On rare occasions the horse or ox is attacked with a skin eruption,
attended with the formation of bullæ or blisters, from the size of a
hazel nut to a hen’s egg, or larger. It is sometimes shown sporadically
and at others appears at once in a large number of animals in the same
herd. The _causes_ are obscure, yet the enzootic appearance of the
affection is suggestive of a common factor entering probably by the
food. Loiset and Seaman have recorded enzootic outbreaks in cattle and
Dieckerhoff in the horse.
_Symptoms_ are cutaneous congestion with the formation of swellings like
a walnut, but exceptionally as large as the fist, on the head, neck and
thorax, which in 2 to 4 days form a large central vesicle, with
yellowish serous contents. Cases in the ox (Loiset, Seaman) had a
similar eruption on the loins, quarters and hind limbs, some of the
swellings attaining the size of a hen’s egg, and with similar contents.
Later these ruptured, crusted over and healed, with, for a time, a
smooth glistening surface. Winkler records cases in swine and
Schneidemühl in dogs, but the condition is rare in both animals.
_Treatment._ To a nutritious, non-stimulating and easily digestible
diet, may be added a course of arsenic and, in low condition, of
bitters. Locally dusting powders of zinc oxide, boric acid, starch and
lysol. Should the exudate form these into hard cakes, they may be
replaced by carbolized oil or, better, a 5 per cent. mixture of ichthyol
in vaseline.