Canker, like thrush, is not generally attended with much lameness. It often astonishes us that, with a foot in such a condition, the animal can progress so soundly. It invariably commences at the seat of thrush or in the cleft of the frog. A liquid more abominable than that of thrush, and rather more abundant, issues from that part. Likewise it frequently exudes from the commissures, which unite the horny sole to the frog. The horn, also, becomes not only disorganized, but more ragged than in thrush. It bulges out at first, and ultimately flakes off, exposing a substance not much more resistant than orange-peel. The substance is horn in a fungoid state. Its fibers run from the center to the circumference; and between the space of each fiber is lodged a clear liquid, which becomes tainted and dark colored by mingling with the horn that it dissolves and corrupts.
THE PRIMARY ESTABLISHMENT OF CONFIRMED
CANKER.
The horn turned back, so as to display the altered
state of the frog, which indicates a severe attack
of the disease.
THE SECOND STAGE OF CANKER.
Showing the great abundance of fungoid horn
secreted around the margin of the foot. No
notice is purposely taken of the frog in this
illustration.
The fungus is secreted in quantity, and always is most abundant when located about the edge of the sole. Here the papillæ are largest, and here the granulations attain their greatest magnitude. The unresistant horn of canker becomes somewhat hard upon the surface of the sole, and large flakes peel off. Cut into, it displays no sensation; and this is fortunate, inasmuch as it considerably reduces the difficulties surrounding the treatment of a badly-cankered foot.
Concerning treatment, when the disease is confined to one hind foot, or even affects both posterior feet, the case may be undertaken with some degree of confidence. When it has involved one or more of the fore feet, it is always difficult to eradicate; and, in the majority of cases—being guided by the age of the animal—a cure had better not be attempted.
When a horse is cankered all round, the disease is apt to seem capricious. It may be cured in three feet; but it will linger in the fourth, resisting art's resources. Suddenly measures before tried in vain seem to be endowed with marvelous efficacy. The diseased member, which hitherto no treatment could touch, now heals as by its own accord. However, before we can express the full of our satisfaction, canker once more breaks out again in one of the feet which had been cured; thus the affection dodges about till patience is exhausted.