556 CANKER. 



ficial sinuses be got rid of at once, in the manner just 

 proposed ; so that the caustic, whose action we cannot 

 watch or control, may be inserted into as few places 

 as may be possible ; besides, while the horse is down, the 

 practitioner has an excellent opportunity of making a 

 perfect examination of the quittor. 



CANKER. 



This afiection has some peculiarities of character ; spread- 

 ing over the surface of the soft parts, particularly of the 

 sensitive frog and sole, and having a fungoid excrescence, 

 somewhat of a hardened texture, and exuding a thin and an 

 offensive discharge ; which inoculates the soft parts within 

 its reach, particularly the sensitive frog and sole, and destroys 

 their connexions with the horny covering. Canker can 

 be safely said to have much constitutional origin ; it is 

 frequently local ; seldom if ever spontaneous ; but either 

 constitutional, or secondary to some affection, as grease, 

 thrush, &c. It appears oftener in hot weather than in cold, 

 and is more frequently seen in crowded and filthy stables than 

 in well-regulated ones. It is now unknown in the army, and, 

 were the same preventive means applied, would be equally 

 unknown elsewhere. The disease originates in various ways : 

 one source, as supposed, but supposed only, is the high 

 heels or calkins of the heavy draught-horse, which remove 

 the frog from that pressure that seems so necessary to its 

 healthy state. The state of wet and filth these horses stand 

 in is a more likely source : moisture applied to the frogs is 

 a most active agent ; it disorganizes the frog itself, and in- 

 creases the growth of the horn on the heels, which aggravates 

 the evil. Another common origin is neglected thrush, 

 wdiich extending beyond the sensitive frog, inflames the 

 vascular sole, and extensive ulceration succeeds. Virulent 

 and neglected grease will often occasion it, and it is no un- 

 common circumstance for quittor to degenerate into canker. 

 When a canker is the consequence of a wound of the sole 

 which extends to the flexor tendon, it is commonly of the 

 worst kind. Treads, bruises, suppurating corns, or what- 

 ever produces inflammation, may occasion canker. 



Treatment of Canker. — The principal indications appear 

 to be, first, to reduce the inordinate increase of parts to 



