Foot-and-Mouth Disease . 
461 
terms, there are in the surrounding circumstances during the 
times of what are commonly called great outbreaks, greater 
powers of action, and in the animal system a greater suscepti- 
bility to be acted on ; this susceptibility, which in ordinary 
seasons is exhausted by one attack, under the new conditions sur- 
vives two or three accessions of disease. The practical conclusion 
from these facts is, that the farmer should never consider his cattle 
secure, but always maintain on his farm the sanitary regulations 
which will be hereafter referred to. 
Sheep are liable to attacks of the foot-and-mouth complaint of 
cattle, but they most frequently suffer from it in a modified form. 
The mouth in most instances does not present the indications of 
disease which are seen in cattle, but the feet are almost without 
exception affected in a characteristic manner. Much discussion 
has arisen out of the circumstance that the vesicular epizootic 
of cattle is often confined to the feet of sheep, and frequent 
attempts have been made to prove that the disease in sheep is 
the common foot-rot, and not the epizootic affection which is 
seen in cattle. It would be impossible by any length of argument 
to convince a large class of practical men whose minds are made 
up on this point, of the fact that a scientific pathologist would 
have no difficulty in deciding at once, as to whether a sheep were 
affected with the aphthous disease, or some common form of foot 
affection ; nevertheless no problem in pathology is more easily 
solved. 
Of the several quite distinct local diseases of the foot of the 
sheep, none is distinguished by the presence of a blister or vesicle 
in any part of the foot, while in the foot-and-mouth disease there 
are always vesicles present, or distinct evidence of their previous 
existence, and there is also a general absence of that condition of 
hoof which is usual in foot-rot. In exceptional cases the hoofs 
are elongated, much broken, and sometimes ragged and rotten ; 
but this condition has nothing to do with the aphthous disease, 
which is indicated by the presence of vesicles between the claws, 
in the posterior part of the foot immediately above the hoof, and 
sometimes exactly on the portion of skin between the digits which 
covers the transverse ligament connecting the two sides of the 
foot together, and which is rendered tense, and therefore distinct 
when the digits are pulled apart. When the posterior part of 
the hoof is separated from the secreting membrane, as it often is 
in foot-and-mouth disease, the vascular surface is seen to be 
congested, but there are no signs of the so-called fungoid 
growths which distinguish foot-rot. In short no two diseases 
can be more distinct from each other in the local appearances ; 
but independently of the evidence afforded by the diseased parts, 
there is in cases of foot-and-mouth disease clear evidence of 
