374 HEALTH AND DISEASE 



Earely it is of a dark watery character. In the former condition it is 

 chiefly made up of young horn cells mingled with varying small propor- 

 tions of pus corpuscles, and occasionally with blood. Usually this disease 

 is unattended with lameness, but in some instances it is very marked, and 

 may be severe. Horses with thrush travel badly on rough roads, owing 

 to the tender frogs being brought into contact with stones. 



Treatment. — In all cases of thrush the system of shoeing should 

 receive attention, and strict injunctions be given to the shoeing-smith to 

 bring the frog gradually to the ground and remove no part of it save 

 such portions as are ragged and disconnected with the parts beneath. A 

 dose of physic or a course of saline medicine may be given in the case of 

 plethoric animals, and the work should be increased. 



As a means of assisting the discharge and bringing about a healthy 

 state of the parts, astringent applications should be made to the frog, after 

 the cleft has been thoroughly freed from dirt, by careful washing with 

 carbolized water. The dressings most commonly used, and which are most 

 effective for the purpose, are sulphate of copper or alum mixed with tar 

 and a little carbolic acid. A solution of chloride of zinc is also a useful 

 application; the ointment of the red oxide of mercury is equally beneficial. 

 Tar dressing is sometimes applied by means of a pledget of tow, and 

 covered over by a leather sole, and if it is required that the horse should 

 work, this protection is in some instances necessary. Besides protecting 

 the diseased part from injury, it has also the advantage of excluding dirt, 

 but it forbids the removal of the application without the removal of the 

 shoe. This difficulty may, however, be in some measure overcome by the 

 use of movable leather pads. 



CORN 



Definition. — A corn is a bruise to the sole of the foot occurring 

 at the iuner heel, in the angle lietween the crust and its inflection — 

 the " bar". The almost invariable occurrence of the injury at this point 

 would seem to be due in part to the inner quarter being weaker and 

 more yielding than the outer one, and in part also to its being more 

 immediately under the centre of gravity. 



The fore-feet are almost invariably its seat, and of these one or both 

 may be affected. 



Causes. — The chief predisposing conditions to corn are the con- 

 formation and structure of the feet, and indifferent shoeing. With regard 

 to the former, it may be remarked that flat feet with low, weak lieels 

 and thin soles and crust are those most likely to contract the disease. 

 Feet of a strong, upright, and blocky type, although less frequently 



