8 
Colorado Experiment Station 
The symptoms may or may not appear on the head, and in some 
instances they may show on the head and not on the feet. In the 
early stages small vesicles may be found in the unfeathered skin 
around the bill and around the eyes. These are followed by con- 
siderable swelling, increasing redness and later by the presence of 
scabs. Often the eyelids become glued together and the chicken 
becomes totally blind. It appears that many chickens starve in this 
stage because of inability to find food. Older chickens are not nearly 
so frequently affected, but when the disease does attack them, it 
produces similar conditions of the feet and shows considerable 
swelling around the eyes with rather extreme redness. Vesicles have 
not been nof^d in hens, it requiring from one to two weeks in most 
instances for the disease to prove fatal ; whereas in small chickens, 
the disease may terminate fatally in one or two days. 
The fiock mortality may run as high as 90 per cent in virulent 
outbreaks. Generally, however, it will not average above 20 per 
cent. Most of the affected birds die and the rest are practically 
worthless, since they become stunted and their feet are so distorted 
that they can not get around readily. As a consequence they are 
frequently destroyed, even though they appear to recover from the 
acute symptoms of the disease. Therefore, it may safely be said 
that of the chickens which are affected, the loss is practically 100 
per cent. 
Differential Diagnosis — The disease is more apt to be mistaken 
for roup than any other malady, but can be rather easily differenti- 
ated since roup is largely a cold weather disease and this appears 
in the summer. Furthermore, the disease under consideration affects 
Showing- typical posture in bad cases. Walking causes such pain Unit I lie ehielien 
sits a great deal. 
