288 PAKTICULAR LAMENESSES. 



articulation and os coronoe. The accompanying figure (Fig. 47) 

 illustrates this. When involving either articulation, ring-bone 

 always causes lameness at its commencement ; but when anchy- 

 losis is completed, such lameness may almost, if not entirely, 

 disappear. 



The lameness of ring-bone precedes the deposition of bony 

 matter, and is due to the presence of inflammation in the bones 

 or synovial membrane. 



The gait of a horse lame from this cause is characteristic. 

 If in the fore extremity, except the deposit be on the posterior 

 aspect, the patient puts his heel to the ground first ; but when 

 in the hind pastern, tlie toe touches the ground first always 

 when it is situated in the upper position, except it be in front ; 

 when in the lower position, the heel comes down first. From 

 this peculiarity in putting the foot to the ground, it is apt to be 

 confounded with laminitis, seedy-toe, and inflammation of the 

 coronary band. It differs from laminitis by the absence of pain 

 at the toe, freedom from fever, &c., and by the heat being con- 

 fined to the upper part of the foot only. 



An examination of the foot will determine whether there be 

 a seedy-toe or a sand-crack in its front ; and the absence of the 

 striated appearance of the wall of the foot will distinguish it 

 from inflammation of the coronary substance. 



PercivaU, waiting in the year 182.3, has thus classified 150 

 specimens of ring-bone. He, however, includes anchylosis of 

 the fetlock-joint under the term : — 



5 complete anchyloses of the fetlock-joint. 

 40 „ „ „ pastern-joint. 



18 „ ,. „ coffin-joint. 



The other specimens were simply encrusted, more particularly 

 around their extremities, with layers of new bone, or were 

 variously deformed with exostoses of different shapes, many of 

 which were very large, and several of them confined to one side. 



My own observations upon, and examinations of, specimens 

 enable me to agree with Percivall, and to differ from Professor 

 Dick and others, who maintained that the lower form was the 

 most common. 



The causes of ring-bone are hereditary, structural, incidental, 

 and rheumatoid. 



Hereditary predisposition is sufficiently proved and acknow- 



