164 



CHAPTER X. 



Diseases and Injueies of the Feet. 



thrush contracted heels canker sandcrack ^false-quarter 



split-hoof acute laminitis chronic laminitis seedy toe 



pumiced feet brittle feet inflammation of the coronet, 



or villitis navicular disease horn tumour wounds and 



bruises of the coronet pricks in shoeing wounds of the 



sole and frog ^corns — -quittor ^forging or clicking, 



Thrush 



is an inflamed condition of the membrane which secretes the horn 

 of the frog. During the presence of inflammation, this membrane 

 forms weak and degraded horn of cheese-like consistence, which 

 readily liquefies under the action of moisture, and produces the 

 characteristic offensive discharge. The longitudinal fissure which 

 exists in the centre of the thick portion of the frog of a foot suft'ering 

 from thrush (Fig. 48) is caused by the failure of the secreting mem- 

 brane to produce sound horn. In a healthy foot, the '' cleft of 

 the frog " is merely a depression (Fig. 49) in the frog substance, 

 and does not penetrate to the sensitive joarts. The two great 

 causes of thrush are want of pressure on the frog, and the decom- 

 posing effect which moisture that is laden with fermenting organic 

 matter, has on the frog. The former cause is greatly aided by the 

 pernicious practices of paring the frog, and using high-heeled 

 shoes ; and the latter, by the retention of dung and urine in the 

 stall or box, and neglect of frequently picking out the feet oi 

 the horses, while in the stable. In India, where the ground is 

 hard, many horses with naturally high heels are very prone to 

 thrush from want of pressure on the frog. Their heels, if not kept 

 sufficiently low, are apt to " wire in," in which case the frog be- 

 comes dry and shrivelled up. As the disease advances, fissures, from 

 which a stinking odour issues, occur on the sides of the frog, close 

 to the heel, and the foot acquires a contracted appearance (Fig. 



