466 IOWA DEPARTMENT OF AGRICULTURE 
curdling. The ulceration of the interdigital tissue may extend to the 
ligaments of the fetlock or produce disease of the joint or bone. Preg- 
nant animals may abort. In pigs, sheep, and goats i^ie lesions in the 
foot are most common, but both forms may be observed or only the 
mouth lesions. 
When the disease has become fully established it will be found that 
the duration of the attack will vary greatly with different animals. From 
ten to tvrenty days are usually required for the recovery of the normal 
appetite and spirits in mild outbreaks, while the return to a full flow of 
milk, in the case of milch cows, is seldom witnessed before the arrival 
of the following season. 
In the malignant type of the disease it requires from three months to 
a year for an animal to recover. The mortality is not great, generally 
about 1 to 3 per cent, but in severe outbreaks it may reach 5 per cent. It 
is more fatal in young animals that have been fed on infected milk, 
and produces death in from 60 to 80 per cent of these cases as a result 
of gastro-enteritis. 
Biagnosis. — The recognition of this affection should not, as a rule, be 
difficult, especially when the disease is known to be in the vicinity; in 
fact, the group of symptoms form a clinical picture too decided to be 
doubted. The combination of high fever, vesicular inflammation of the 
mouth, and hot, painful, sw^ollen condition of feet, followed in twenty-four 
to forty-eight hours by the appearance of numerous small vesicles varyitfg 
in size from that of a pea to that of a hazel nut on the udder and feefe 
a,nd in the mouth should prevent any serious or long-continued error In 
the diagnosis. However, in the inoculation of calves we have a certain 
final test. In twenty-four to seventy-two hours after inoculation the calves 
present the characteristic vesicles. Such inoculation should be practiced, 
however, only by officials who are properly authorized to deal with con- 
tagious diseases. 
Differential Biagnosis. — It can be asserted positively that no disease 
of cattle closely simulates the symptoms of the eruption of aphthous 
fever on the lining membrane of the mouth. Cowpox or horsepox may- 
be accidentally transmitted by inoculation. But the eruption in the "pox" 
goes on to the development of a pustule, while in foot-and-mouth disease 
the eruption is never more than a vesicle, even though the contained 
fluid may become turbid. 
The inoculation test in the case of cowpox does not respond with fever 
and eruption for at least ten days, and often longer. 
In mycotic stomatitis or inflammation of the lining membrane of the 
mouth the entire buccal cavity is inflamed and in a few days the croupops 
membrane forms, peels off, and exposes a raw, bleeding surface, while the 
thin skin between the toes may also be inflamed. The previous history 
of the case; the failure of the vesicles, if any appear, to spread exten- 
sively; the absence of vesicular eruptions on other portions of the body, 
notably the udder and teats, and characteristically, the hoof, together 
with the absence of infection in the herd and the complete negative char- 
acter of inoculation of calves, distinguish between the local disease named 
and foot-and-mouth disease. 
