KNEE, FETLOCK, ANKLE, AND FOOT. I97 



affected by an inflammatory action set up in the periosteum and bone 

 tissue proper of the large and small pastern bones. 



Causes. Injuries, such as blows, sprains, overwork in young unde- 

 veloped animals, fast work on hard roads, jumping, etc., are among the 

 principal exciting causes of ringbones. Horses most disposed to this 

 disease are those with short upright pasterns, for the reason that the 

 shock of locomotion is but imperfectly dissipated in the fore-legs of these 

 animals. Improper shoeing, such as the use of high calks, a too great 

 shortening of the toe and correspondingly high heels; predispose to this 

 disease by increasing the concussion to the feet. 



Symptoms. The first symptom of an actively developed ringbone 

 is the appearance of a lameness more or less acute. If the bony tumour 

 forms on the side or upper parts of the large pastern its growth is gen- 

 erally unattended with acute inflammatory action, and, consequently, 

 produces no lameness or evident fever. These are called false ringbones. 

 But when the tumours form on the whole circumference of the ankle, or 

 simply in front under the extensor tendon, or behind under the flexor 

 tendon; or if they involve the joints between the two pastern bones, or 

 between the small pastern and the cofiin bone, the lameness is always 

 severe. These constitute the true ringbone. Besides the lameness the 

 ankle of the affected limb presents more or less heat, and in many in- 

 stances a rather firm, though limited, swelling of the deeper tissues over 

 the seat of the inflammatory process. The lameness of ringbone is char- 

 acteristic in that the heel is first placed on the ground when the disease 

 is in a fore-leg, and the ankle is kept as rigid as possible. In the hind- 

 leg, however, the toe strikes the ground first when the ringbone is high 

 on the ankle, just as in health; but the ankle is maintained in a rigid po- 

 sition. If the bony growth is under the front tendon of the hind-leg, or 

 if it involves the coffin joint, the heel is brought to the ground first. In 

 the early stages of the disease it is not always easy to diagnose ring- 

 bone; but when the deposits have reached some size they can be felt and 

 seen as well. 



The importance of a ringbone of course depends on its seat, and often 

 on its size. If it interferes with the joints, or with the tendons, it may 

 cause an incurable lameness even though small. If it is on the sides of 

 the large pastern, the lameness generally appears as soon as the tumour 

 has reached its growth and the inflammation subsides. Even where 

 the pastern joint is involved, if complete anchylosis results, the patient 

 may recover from the lameness with simply an imperfect action of the 

 foot remaining, due to the stiff joint. 



