210 DISEASES, OF THE FEET. 



toe " as a rule, a style of progression he would hardly adopt, if the 

 disease had been brought on by identically the same course of 

 action (raising the heel from the ground) by which he now strives 

 to relieve the inflamed parts from pain. Also, a horse thus 

 affected, almost always goes better in a high-heeled shoe, than in a 

 low-heeled one; because, raising the heel tends to flex the pedal 

 joint, and, consequently, to relieve, to some extent, the inflamed 

 structures from the painful pressure of the perforans tendon. 



4. Compression. The degree of compression on the navicular 

 bone is affected by the rate of speed, and the weight of the rider 

 or of the conveyance; but not by the nature of the ground. 

 Consequently, if compression was the chief cause of this disease, 

 racehorses, chasers, hunters, and heavy cart-horses (especially those 

 which wear " toe-pieces " to their shoes) would be the chief 

 sufferers. On the contrary, they are all but exempt ! 



5. Rheumatism. Beyond the supposition that chill, as seen 

 (p. 206), has a predisposing influence, I know no argument which 

 would support the theory that rheumatism can originate this 

 disease. 



6. Heredity, no doubt, has a strong predisposing influence ; 

 but I have met with no proof that, of itself, it can produce the 

 disease. 



7. Direct injury may, in some rare instances, give rise to this 

 malady. Its influence must be extremely small, considering that 

 only two cases (see next paragraph) in the hind feet have been 

 reported. 



SPECIAL LIABILITY OF THE FORE FEET TO NAVICULAR 

 DISEASE. — The extraordinary difference in this respect between 

 the fore and hind feet (only two cases presumably having been 

 recorded) cannot be accounted for by the fact that horses, when 

 standing, are accustomed to rest their hind limbs, alternately, 

 while remaining " level " in front ; because, as I have already 

 remarked, long-continued standing (of, for instance, from one tn 

 four months on board ship during sea voyages) appears to have 

 no influence in setting up navicular disease ; although it is a very 

 potent agent,in bringing on laniinitis. Taking into consideration 

 the large part played by concussion in the production of navicular 

 disease, I am convinced that the difference in liability is chiefly, 

 if not wholly, due to the fact that far more concussion falls on the 

 fore feet than on the hind feet. 



SYMPTOMS. — By actual examination of the foot, an observer 

 will discover little to indicate the nature of the ailment ; though 

 he may guess at its existence from the absence of signs of other 



