816 
DISEASES OF THE FOOT. 
and accidental injury, not to the diseased process. When the condition 
is neglected it continuously advances, until finally it affects the entire 
matrix, and may lead to loss of the hoof. 
Causes. The causes of canker are at present little understood, and 
opinions as to the nature of the disease vary greatly. The name is a 
very old one, and originated at a time when it was customary to describe 
many different disease processes, distinguished by their malignant 
character, by the same term. It has long been recognised that canker 
has no real relationship with carcinoma or cancroid, and therefore, 
strictly speaking, the name is unjustifiable. The disease is commonest 
in animals of a lymphatic temperament, and is favoured by dirty, ill- 
drained stables, where animals stand continually on litter soiled with 
manure, and saturated with decomposing, ammoniacal urine. Canker 
is probably due to specific infection, as seems indicated both by its course 
and the manner in which it reacts to treatment, but the infection does 
not appear to be due to a single organism, but to several, which do not 
always agree in their method of action. Megnin has described one which 
he terms Iveraphyton. (The subject receives further attention in Dollar 
and Wheatley’s book on “Horse-shoeing and the Horse’s Foot,” p. 400.) 
Prognosis. Although canker always takes a chronic course, yet it 
shows many variations which are of real importance in forming a 
prognosis. Under any circumstances the practitioner should be 
cautious in giving an opinion, though the greater number of cases 
lecover. In forecasting the probable result the following points must 
be considered:— 
(1) The nature of the growth. The more active the growth in the 
rete tissue and papillae, and the softer the material produced, the graver 
the case. When the papillary growths retain their form, the case is 
more hopeful than when they are amorphous. 
(2) The area involved. The greater the tendency to extend, and the 
more widespread the disease, the less the chance of recovery. Treatment 
is paitieularly difficult when the laminae are attacked, easier when the 
condition is confined to the frog and sole. Rapid extension is always 
an unfavourable sign. 
(8) The most difficult cases are those in which a predisposition to the 
disease exists, as shown by several feet being affected. 
(4) Treatment is, of course, more difficult in restless and sensitive 
animals, and the prognosis correspondingly less favourable. The treat¬ 
ment, in fact, lequires a great deal of patience, on the part not onlv of 
the veterinary surgeon, but also of the patient and owner. 
Treatment. Perhaps in no other disease have so many drugs been 
tried as in canker. As indicated elsewhere, the selection of a proper 
material certainly plays a very important part in treatment, and only 
