342 DADD'S VETERINARY MEDICINE AND SURGERY. 



foot. The navicular bone (sometimes called the shuttle-bone 1 ) \s 

 so placed as to strengthen the union between the lower pasters 

 and the coffin bone, and to enable the flexor tendon, which passes 

 over it, in order to be inserted into the bottom of the coffin bone, 

 to act with more advantage. There is a good deal of weight 

 thrown on the navicular bone, and from the navicular bone to 

 ihe tendon, and there is a great deal of motion or play between 

 them in the bending and extension of the pasterns. It is very 

 easy, therefore, to conceive that from sudden concussion, or from 

 rapid and unrestrained motion, the delicate membrane which covers 

 the bone, or the cartilage of the bone, may become diseased. The- 

 bone sometimes becomes ulcerated and fractured, so that it renders 

 the horse almost perpetually lame. 



Symptoms. — The principal symptom of this affection is pointing 

 of the foot. If the horse be watched, when standing still in the 

 stable or on the street, it will be noticed that the affected limb is 

 advanced or pointed in such a manner as to relieve the navicular 

 bone of any pressure from the flexor tendon, and this occurs in 

 the chronic stage as well as in the acute. It will be observed, 

 also, that the animal, when traveling, takes short steps, goes on 

 the toe, and tries to favor the heel, or posterior parts, as much as 

 possible. The favoring of the heel tends to destroy the function 

 of expansibility of the hoof, and contraction of the same is the 

 result. 



Treatment. — Should the disease be discovered early, that is, in 

 the acute stage, the foot should be placed in a boot lined with a 

 sponge. The latter is to be kept constantly wet with a portion 

 of vinegar and water, equal parts. This may be continued for a 

 period of twenty-four hours, at the end of which time bathe the 

 coronet and heels with tincture of arnica. Light diet and perfect 

 quiet, as in every other variety of inflammatory disease, are always 

 necessary. 



In old chronic cases we resort to counter-irritation, through re- 

 peated applications of the acetate of cantharides. Should there be 

 any appearance of contraction, the heels of the hoof must be well 

 opened, and the walls of the hoof, near the heels, must be rasped 

 thin, so as not only to favor the expansibility of the foot, but also 

 with a view to relieve the navicular region of any undue pres- 

 sure, 



