THRUSn. 
183 
inflammation the lower surface of the sensible frog secretes 
pus instead of the horny substance, which is its proper 
function. When the frog is in a healthy condition, the cleft 
sinks but a small way into it. Contraction, however, or any 
other disease, affects the cleft so that it extends in length 
and often penetrates deep into the sensible horn within, and 
it is through this diseased and deepened fissure that the 
matter from the thrush discharges itself. Any complaint 
which affects the healthy condition and action of the frog, 
is almost sure to induce thrush. Differing from most dis¬ 
eases of the foot, thrush is generally more severe in the 
hind than in the fore feet. This can only be accounted for 
by bad stable management, and that the hind feet are sub¬ 
jected to being so much exposed to the baneful conse¬ 
quences of immersion in the dung and urine, producing 
irritation, and generating disease. Besides, the hind feet are 
further removed from the centre of circulation than the 
fore, which consequently subjects them to the accumulation 
of matter and grease, as well as other affections to which 
they are liable. Contraction is generally the cause of 
thrushes in the fore feet. Wiring-in of the heels will 
produce pressure on the frog, and cause pain and inflam¬ 
mation. 
A horse may have thrush without being lame, and it 
often happens that no alteration whatever can be seen on 
the foot thus diseased, and it may require a close inspection 
to detect that it is affected. But it will always be mani¬ 
fested by the disagreeable and peculiar smell which inva¬ 
riably accompanies the complaint. In some cases no 
tenderness of the frog attends thrush, and therefore the 
horse is not reckoned legally unsound by many persons. 
This we, however, consider strange, as it is a complaint 
which may, and indeed is likely to assume a worse aspect 
