580 DISEASES OF THE HOBSE. 



diseased, although the cows and sheep of this farm remained un- 

 affected. 



Symptoms. — The commencement of the disease is usually unob- 

 served b}^ 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 vertebrae 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 or 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 ver}'^ 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, v/iir 

 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 maj^ 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 tin 

 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 

 Imibs, 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 



