THRUSH. 537 
finger, showing that the bone is denuded, and most probably carious. 
There is generally a considerable increase of temperature in the foot, 
and always more or less lameness, with, in most cases, swelling of the 
bulbous heels and coronet. On examining the sole carefully, some part 
will either show a difference of colour from the adjacent horn, or there 
will be a yielding on pressure, owing to its being undermined. ‘The treat- 
ment must be conducted on the same principle as for fistulous sores. In 
the first place, a dependent opening must be formed, so that no matter 
shall be confined, but it shall be allowed to come away as fast as it forms. 
This can only be done by probing ; and if the original opening is in the 
coronet, the probe must be passed down as low as possible, and then the 
sole should be pared away till the end can be reached. In tolerably 
recent quittors, this plan alone will allow the sinus to heal; but in old 
ones, the internal surface has become callous, and no granulations are 
thrown out. Here an injection should be thrown in every day with a 
syringe, a saturated solution of sulphate of zinc being that generally 
recommended ; but I have found the chloride answer still better, using 
one drachm of the salt to a pint of watar at first, and going on up to two 
drachms. By injecting this daily, and introducing a piece of lint, wetted 
with it, into the superior opening, leaving the lower one free, I have cured 
many bad quittors, even when there was evidence of caries of the coffin- 
joint. The disease requires a careful adjustment of the remedies to its 
extent and nature, and a theoretical description of it is of little use. 
THRUSH. 
ANY OFFENSIVE DISCHARGE FROM THE FROG is called by this name, 
although the cause and treatment may be as different as possible. It 
varies greatly in the fore and hind feet ; and, indeed, it must never be 
forgotten that, in every case, the cause which has produced the discharge 
must be clearly made out before any plan of treatment can be carried out 
with any prospect of success. Sometimes thrush is merely the result of 
the decomposition of the horny frog, from the foot being constantly kept 
wet with urine, which is most common in the hind foot. Here the surface 
becomes soft, and is gradually dissolved ; while the cleft, from its retain- 
ing the moisture, is increased in size. ‘This state is often brought on by 
the too frequent use of cowdung-stopping in horses with soft frogs ; and, 
instead of doing good by his treatment of the foot, the groom is really 
destroying it by encouraging the decomposition of the healthy defence 
which Nature has given to it. For this kind of thrush, very little treat- 
ment is required, if the cause which produced it is withdrawn. Still, it is 
not always easy to keep the frog dry, and stop the decomposition, without 
the application of some astringent ; and if the mere use of dry litter, and 
the application of tar ointment, do not seem to harden the frog at once, it 
may be touched with a wash composed of ten grains of bluestone to the 
ounce of water. .This will soon dry it; or, if it fails by any chance, the 
chloride of zinc may be used in the same way, by dissolving five grains in 
an ounce of water. 
THE SECOND KIND OF THRUSH is that in which from a gross habit of 
body there is a simple inflammation of the sensible frog, and instead of 
sound horn being secreted, a spongy substance is deposited, which breaks 
away in places, and the frog looks ragged and uneven, with a greasy 
surface, smells very foul, and feeds hot to the touch. Here the treatment 
must be general as well as local. A dose of physic should be given, the 
