580 DISEASES OF THE HORSE. 
diseased, although the cows and sheep of this farm remained un- 
affected. 
Symptoms.—The commencement of the disease is usually unob- 
served by the owner, and those symptoms which do develop are gen- 
erally not well marked or are misleading unless other cases have been 
noted in the vicinity. Until the bones become enlarged the symp- 
toms remain so vague as not to be diagnosed readily. The disease 
may be present itself under a variety of symptoms. If the bones of 
the hock become affected, the animal will first show a hock lameness. 
If the long bones are involved, symptoms of rheumatism will be the 
first observed, while if the dorsal or lumbar vertebre are affected 
indications of a strain of the lumbar region are in evidence. Prob- 
ably the first symptom to be noticed is a loss of vitality combined 
with an irregular appetite cr other digestive disturbance and with 
a tendency to stumble while in action. These earlier symptoms, how- 
ever, may pass unobserved, and the appearance of an intermittent 
or migratory lameness without any visible cause may be the first sign 
to attract attention. This shifting and indefinite lameness, involv- 
ing first one leg and then the other, is very suggestive, and is even 
more important when it is associated with a tendency to lie down 
frequently in the stall and the absence of a desire to get up, or the 
presence of evident pain and difficulty in arising. 
About this time, or probably before, swelling of the bones of the 
face and jaw, which is almost constantly present in this disease, will 
be observed. The bones of the lower jaw are the most frequently 
involved, and this condition is readily detected with the fingers by 
the bulging ridge of the bone outside and along the lower edge of the 
molar teeth. A thickening of the lower jawbone may likewise be 
identified by feeling on both sides of each branch at the same time 
and comparing it with the thinness of this bone in a normal horse. 
As a result mastication becomes difficult or impossible and the teeth 
become loose and painful. The imperfect chewing which follows 
causes balls of feed to form which drop out of the mouth into the 
manger. Similar enlargements of the bones of the upper jaw may be 
seen, causing a widening of the face and a bulging of the bones about 
midway between the eyes and the nostrils. In some cases the nasal 
bones also become swollen and deformed, which, together with the 
bulging of the bones under the eyes, gives a good illustration of the 
reason for the application of the term bighead. 
Other bones of the body will undergo similar changes, but these 
alterations are not so readily noted except by the symptoms they 
occasion. The alterations of the bones of the spinal column and the 
limbs, while difficult of observation, are nevertheless indicated by 
the reluctance of the animal to. get up and the desire to remain 
lying for long periods of time. The animal easily tires, moves less 
