THE FOOT. 337 



foot with the other ; by the deviation of some of the superior regions 

 or articulations ; and, finally, by the shoeing." 



In all diseases of the foot the horse, when exercised at a walk or 

 the trot, does not make a free and equal contact with the ground upon 

 the whole of the plantar surface of the foot ; certain movements are 

 precipitated, others are effected in preference upon the toe, upon one 

 quarter more than the other, or again upon the heels. 



We must confine ourselves, not to go beyond our domain, to the 

 enumeration of the principal of these diseases, by simply mentioning in 

 what they consist. 



Contraction of the Foot. — Contraction of the foot (hoof-bound) is 

 the more or less marked contraction of the foot in its posterior parts. 



It is distinguished as true and false, according to the form which it assumes. 



In true contraction the diminution of the lateral diameter affects the quarters 

 as well as the heels, which are always very high ; and hence such a foot is qual- 

 ified mule's foot. As a consequence of the compression, the sole becomes more 

 concave and the frog, in a great measure, becomes atrophied. 



It is nearly always acquired, and occurs more frequently in meridional 

 horses than in any others. The causes are numerous, but all can be traced to 

 one of two factors : desiccation of the horn or interference with its normal elas- 

 ticity. 



In false contraction, known under the name contraction of the heels {narrow 

 heels, compressed heels, etc.), the hoof preserves its ordinary form, except in the 

 region of the heels, which are more or less drawn towards each other without 

 attaining the excessive height which they assume in true contraction. 



Inflammation of the Frog, Thrush. — These are two inflammatory con- 

 ditions of the frog, which are accompanied by a separation of the horn, with a 

 blackish, purulent, and very fetid discharge, emanating from the median and 

 the lateral lacunae, principally from the former, especially when in feet in which 

 it is prolonged between the two heels. 



Canker. — In canker the horn of the frog first, and then that of the sole, 

 softens, separates, and, finally, is shed, thus exposing the living tissues, whose 

 papillae, very hypertrophied, form fleshy vegetations, often voluminous, known 

 under the name ,^ci. These alterations of the keratogenous membrane, which 

 have a tendency to spread to the surrounding healthy tissues, discharge an abun- 

 dant caseous secretion of a very fetid odor. 



Seams. — Seams (cracks) are longitudinal fissures of the wall, which extend 

 from the inferior border to the coronary band or to the vicinity of the latter. 



They are called complete when, involving the entire length and thictness of 

 the wall, they extend to the podophyllous tissue ; they are qualified incomplete 

 in the contrary case. 



Relatively to their seat, they are distinguished as follows : quarter seam, the 

 complete fissure of the quarter, which is more common in the anterior members, 

 and on the internal side more than the external side. 



Seam of the toe (toe-crack), fissure of the toe; it occurs more frequently in 

 the hind- than the fore-foot, and as it seems to divide the foot into two lateral 

 moieties, the animal is, on this account, sometimes called clovenfooted. 



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