LAMENESS IN THE PHALANGEAL REGION. 73 



Differential Diagnosis. — In colts, on account of the 

 incomplete growth of the hoof, the coronet joint lies higher 

 and the phalangeal extremities are more prominent ; but the 

 absence of lameness, and the fact that the young animal 

 supports weight with all its feet normally, will settle any 

 doubt. Sideboues ought not to be mistaken for low ringbone 

 when palpation is properly conducted. Careful palpation 

 will also differentiate thickened conditions of the skin about 

 the regions usually showing rirgbone, but some trouble may 

 be experienced in differentiating sprain of the coronet joint 

 from ringbone. In these cases the increased temperature 

 of the part upon pressure and the history will usually suffice 

 to recognize this as distortion of the coronet joint, bearing 

 in mind that no increased heat or pain is noticed on 

 palpation in true ringbone. 



10.— Fracture of the Navicular Bone. 



History. — Sudden severe lameness following jumping, 

 stopping the animal suddenly while going at a rapid gait, 

 nail punctures, etc. 



Inspection. — The lame leg is constantly kept in the air, or 

 rests on the toe. When the animal is obliged to support 

 weight with the lame leg it will do so most cautiously, with 

 excessive volar flexion of the phalanges, the toe being held 

 obliquely downward and backward. Later on swelling 

 appears in the hollow of the heel. 



Palpation. — Intense pain is produced by raising the foot 

 and practicing forced dorsal flexion of the phalanges, by 

 extending the toe and pushing it in an upward direction. 

 In the one case met with by the writer, which was in a 

 trotting hoi'se going at a 20 gait, and suddenly stopped on 

 the track to avoid a collision, seen about four hours after 



