Thrush is an irritation that takes place first in the cleft of the frog and the deep fissures at the sides of the frog and, if allowed to run on, the entire frog becomes undermined and diseased. It is most common in the hind feet and is generally due to standing in wet and filthy stables. It can be easily recognized by the fetid smell when the foot is cleaned.

Treatment. - Remove the shoe; clean the foot thoroughly and remove any loose parts of frog that may cover a diseased part. If the case is only an ordinary one, dissolve one ounce of sulphate of copper in one pint of water and saturate the affected part with it once a day for two or three days, then press the crevices full of cotton saturated with pine tar. In severe cases it may be necessary to soak the foot two or three hours a day for a couple of days in the following: Sulphate of copper, one pound; warm water, five gallons; then saturate the affected part once a day with the following: Chloride of zinc, four drachms; water, one pint; and as soon as the parts begin to harden, the zinc should be omitted and the tar and cotton used as before.