382 



HEALTH AND DISEASE 



Fig. 398. Canker 



Treatment. 



the course of which the horny covering becomes broken up into coarse, 

 brush-like fibres, having no disposition to cohere and form sound horn 

 (fig. 398). Later, the horn-producing power of the affected parts be- 

 comes enfeebled and ultimately destroyed, and a thick fleshy growth 

 appears, covered with enlarged papillae and a stinking mass of degraded 

 horn cells (fig. 399). Unless arrested, the disease 

 spreads from the horn -denuded sole to the heels and 

 quarters until the foot becomes stripped of its hoof and 

 greatly disorganized. In the early period of the disease, 

 and even when it is considerably advanced, lameness 

 may be altogether absent or very inconsiderable, and the 

 slow progress of the malady enables horses affected by 

 it to continue in work for some time; but as the foot 

 becomes more and more bereft of its horny covering, 

 pain and lameness increase until the animal, though 

 otherwise healthy, is rendered unworkable and useless. 

 -When these cases are promptly taken in hand and judi- 

 cipusly treated, arrest of the disease is possible; but in the great majority of 

 instances the hopeful period is allowed to pass by before anything is done, 

 when it runs its course unchecked. Once fairly established, the prospects 

 of recovery are very remote, and in the most favourable circumstances 

 success can only be looked for after months of treatment and an outlay 



often exceeding the value of the patient. Where 

 treatment is determined upon, a dose of physic 

 should be given at the outset, followed by a 

 restricted diet. The diseased foot should then be 

 thoroughly cleansed and disinfected by long im- 

 mersion in a pail of antiseptic solution, the active 

 principle of which may be carbolic acid, perchloride 

 of mercury, or chloride of zinc. This done, all 

 loose horny shreds should be removed, as well 

 as horn underrun by the disease. Where fungous 

 growth is exuberant it should be removed, either 

 by the hot iron lightly applied or by some caustic 

 agent, such as strong solution of chloride of zinc, powdered perchloride 

 of mercury, sulphuric acid, or nitrate of silver. On the top of the caustic 

 application a thick pad of tow should be placed so as to impart pres- 

 sure to the diseased surface, and when bound on to the foot the whole 

 may be transferred to a suitable " boot ", and the dressing renewed at 

 intervals of two or three days for so long as may be necessary. These, 

 however, are not cases in which amateur doctoring is likely to succeed. 



Fig. 399. Canker 



