described in this
connection.

THRUSH.

Thrush is characterized by an excessive secretion of unhealthy matter
from the cleft of the frog. While all classes of horses are liable to
this affection, it is more often seen in the common draft horse than in
any other breed, owing to the conditions of servitude and not to the
fault of the breed. Country horses are much less subject to the
disease, except in wet, marshy districts, than are the horses used in
cities and towns.

_Causes._--The most common cause of thrush is the filthy condition of
the stable in which the animal is kept. Mares are more liable to
contract the disease in the hind feet when filth is the cause, while the
gelding and stallion are more liable to develop it in the fore feet.
Hard work on rough and stony roads may also induce the disease, as may a
change from dryness to excessive moisture. The latter cause is often
seen to operate in old track horses, whose feet are constantly soaked in
the bathtub for the purpose of relieving soreness. Muddy streets and
roads, especially where mineral substances are plentiful, excite this
abnormal condition of the frog. Contracted heels, scratches, and
navicular disease predispose to thrush, while by some a constitutional
tendency is believed to exist among certain animals which otherwise
present a perfect frog.

_Symptoms._--At first there is simply an increased moisture in the cleft
of the frog, accompanied with an offensive smell. After a time a
considerable discharge takes place--thin, watery, and highly offensive,
changing gradually to a thicker puriform matter, which rapidly destroys
the horn of the frog. Only in old and severe cases is the patient lame
and the foot feverish--cases in which the whole frog is involved in the
diseased process.

_Treatment._--Thrushes are to be treated by cleanliness, the removal of
all exciting causes, and a return of the frog to its normal condition.
As a rule, the diseased and ragged portions of horn are to be pared away
and the foot poulticed for a day or two with boiled turnips, to which
may be added a few drops of carbolic acid or a handful of powdered
charcoal to destroy the offensive smell. The cleft of the frog and the
grooves on its edges are then to be cleaned and well filled with dry
calomel and the foot dressed with oakum and a roller bandage. If the
discharge is profuse, the dressing should be changed daily; otherwise it
may be left on two or three days. Where