314 DISEASES OF THE HORSE’S FOOT 
Differential Diagnosis and Prognosis.—Perhaps the only 
disease with which canker may be confounded is thrush. 
They should, however, be easily distinguishable. The dis- 
charge from thrush is not so profuse, and is thicker and 
darker in colour, while the loosening of the horn is almost 
entirely absent. Furthermore, thrush shows no tendency 
to spread, and, even when left untreated, may remain 
confined to the frog for months, and even years. Canker, 
on the other hand, is slowly progressive, and soon shows 
the characteristic fungoid excresences, which growths are in 
thrush never seen. A further point of difference is dis- 
covered when treatment is commenced. Canker is found 
to be refractory to a point that is absolutely disheartening, 
while thrush, with careful attention, is soon got under hand, 
and a permanent cure effected. 
The prognosis must be guarded. By many canker has 
been said to be incurable. This, however, has been clearly 
shown to be wrong. When the animal is young, and treat- 
ment may reasonably be judged to be economical, then a 
favourable prognosis may be indulged in, provided the 
veterinary surgeon intends to put into that treatment a 
more than ordinary amount of individual care and atten- 
dance. Even then, however, he will have to be very largely 
guided by the condition of his case. He should see that it 
is not too far advanced, and that a great deformity of the 
hoof, or actual exploration, does not indicate disease of the 
greater part of the wall. 
Treatment.—From what has gone before, it will be seen 
that the eradication of canker is no easy task, that it is, 
in fact, a most difficult matter, and one not to be lightly 
undertaken. At the risk of recapitulating what we have 
said before, we may mention here the two points which the 
veterinarian must bear in mind. (1) That there is no 
actual disease or alteration in structure of the deep layers 
of the keratogenous apparatus. It is only the superficial, 
or horn-secreting, layer that concerns us. (2) That the 
disease of this superficial layer is infection with a material 
that may reasonably be presumed to be infective. 
