enous injections
of Fowler's solution of arsenic give temporary relief, but relapses
occur. In view of the great economic importance of this disease, it
would not be advisable to attempt to treat any sporadic cases should
they occur in this country. On the contrary, the animals should be
slaughtered immediately and their carcasses promptly burned.

OSTEOPOROSIS OR BIGHEAD.

By JOHN R. MOHLER, V. M. D., _Assistant Chief, Bureau of Animal
Industry_.

Osteoporosis is a general disease of the bones which develops slowly and
progressively and is characterized by the absorption of the calcareous
or compact bony substance and the formation of enlarged, softened, and
porous bone. It is particularly manifest in the bones of the head,
causing enlargement and bulging of the face and jaws, thereby giving
rise to the terms "bighead" and "swelled head," which are applied to it.
The disease affects horses, mules, and asses of all ages, classes, and
breeds, and of both sexes, and is found under all soil, dietetic, and
climatic conditions. It may occur in sporadic form, but in certain
regions, such as South Africa, Australia, Madagascar, India, Hawaii, and
in this country it seems to be enzootic, several cases usually appearing
in the same stable or on the same farm, and numerous animals being
affected in the same district. In the United States the disease has been
found in all the States bordering the Delaware River and Chesapeake Bay,
in some of the New England States, and in many of the Southern States,
especially in low regions along the coast. In Europe the disease appears
to be quite rare, and is usually described as a form of osteomalacia, a
disease which is not uncommon among cattle of that continent. The
opinion that bighead is only a form of osteomalacia, however, can not be
accepted, nor can the infrequency of the former among European horses
and the frequency of the latter among other live stock be conceded on
the argument which has been presented, namely, that the better care
which horses receive prevents them from becoming affected. In the
Southwest, where osteomalacia, or creeps, has not infrequently been
observed among range cattle by the writer, no case of osteoporosis of
the horses using the same range has been noted, although the latter
animals are given no more attention than the cattle.

The appropriate treatment of osteomalacia in cattle is so effective that
if osteoporosis were a similar manifestation of dis