POSTERIOR MEMBER. 311 



The osseous tumors of the region have received the name ring-bone, and are 

 located on the anterior and the lateral faces. Clinically, they are distinguished 

 as coronary and cartilaginous, according as they are developed upon the second 

 phalanx or in the thickness of the lateral cartilages of the foot. 1 



They are usually, to whichever variety they may belong, the consequence of 

 violent percussions received by the bones during locomotion, or of contusions of 

 the cartilages. They also follow inflammatory conditions of a diverse nature, such 

 as abscesses of the coronet, tendinous or cartilaginous quitter, the prick_of a nail, 

 etc. ; finally, they are frequently sequelae to fractures, in which case it is observed 

 they are persistent. Short-jointed horses, young horses with a precocious consti- 

 tution, which are subjected to laborious work, and full-grown horses which are 

 employed in severe labor on the pavements of large cities are much more pre- 

 disposed to such formations than others. The influence of heredity has been 

 recognized for a long time ; certain families of horses, from injudicious selections 

 or crossing, invariably transmit these blemishes to their descendants. 



Ring-bones are recognized by a hard, resisting tumefaction, which covers the 

 anterior or lateral faces of the coronary region, and manifests itself as an abnor- 

 mal convexity when the animal is examined from in front or in profile. Although 

 the enlargement is most often apparent to the eye, it is sometimes concealed by 

 the thickness of the integument and the abundance of the hairs ; it is therefore 

 necessary to complete the examination by the use of the hand, especially in 

 horses whose coronet is not very distinct in its outlines. 



A ring-bone most usually at its beginning occasions lameness ; but when the 

 tumor is once formed the lameness disappears, unless the exostosis has reached 

 the contour of the articular surfaces. 



Knuckling also appears as a complication of old ring-bones ; to this symptom 

 may be added contraction of the hoof, due to the deviation of the coronary band. 



These exostoses always constitute a serious blemish, but the degree of the 

 gravity nevertheless varies. It is clear that the depreciation of the value of the 

 animal is greater as he is one of luxury or a rapid motor, and as the interference 

 with the locomotory functions is more pronounced. Many horses are but little 

 depreciated even by a voluminous ring-bone which is not accompanied by lame- 

 ness, or whose lameness does not interfere with their utility as draught-horses. 

 It is entirely different with pleasure-horses, in which the perfectness of conforma- 

 tion and the cleanness of the members form one of the essential conditions of 

 their acquisition. Finally, these exostoses are, from their hereditary tendency, 

 an absolute reason for condemning such horses as are destined for breeding purposes. 



The coronet rather frequently presents on its surface traces of the actual 

 cautery in points or in lines. We will repeat here the advice we have so often 

 given in such cases : it is necessary to ascertain by a minute examination that 

 the diseased processes against which this treatment has been employed have 

 really disappeared. Certain horse-dealers, indeed, have applied, with fraudulent 

 intent, the actual cautery upon the member for the concealment of a lameness 

 whose seat is more or less distant from the cauterized parts. 



Let us remark, in terminating, that there is a particular variety of scabies or 

 mange affecting the inferior extremities of the members of the horse ; it is qual- 

 ified symbiotic or chorioptic mange, because it is caused by an acarus named sym- 



1 These are ordinarily called side-bones. 



