AND MALP^ORMATIONS OF THE FEET. 87 



In these cases it will be necessary to have re- 

 course to the veterinary surgeon. The disease has 

 now lost its name of thrush, and is known as canker. 



76. Canker is a morbid secretion of the sensitive canker. 

 frog and sole, involving of course the correspond- 

 ing insensitive parts. This formidable disease 

 generally has its origin in neglected thrush. As 

 stated above, it is a case for the veterinary surgeon, 

 not for the farrier, though it may be remarked in 

 passing, that the application of pressure to the 

 diseased part, as in the case of thrush, combined 

 with the use of the strongest caustics, is the great 

 aim in treatment. 



77' Navicular disease in its primary stage is Navicular 

 inflammation of the flexor perforans tendon and 

 its investing sheath, at the point where it bends 

 and passes round the navicular bone, just prior to 

 its insertion into the coffin bone or bone of the foot. 



This inflammation arises from strain or over- 

 taxing of the tendon, and in some cases from 

 laceration of some of its fibres. The liability to 

 strain at this particular point is owing to the very 

 sharp bend which the tendon here makes round 

 the navicular bone. Greater stress must from this 

 formation come on it here than at any other part. 



In the second stage the inflammation extends 

 from the tendon and its sheath to the bone itself. 

 The result of the inflammation thus set up in the 



