150 DISEASES OF THE HORSE'S FOOT 



bring it about. Thus, in an animal at grass, with, according 

 to the weather conditions, an alternate moistness and 

 dryness of the pasture, with its consequent influence on 

 the horn secretion, these rings nearly always appear. The 

 effects of repeated blisters to the coronet make themselves 

 apparent in the same way, and testify to the efficacy of 

 blisters in this region in any case where an increased 

 growth of horn is deemed necessary. From this it is clear 

 that the condition depends primarily upon the amount and 

 condition of the blood supplied to the coronary cushion. 

 Thus, fluctuations in temperature during a long-continued 

 fever, or the effects of alternate heat and cold, or of healthy 

 exercise alternated with comparative idleness, will each rib 

 the foot in much the same manner. 



Treatment. — The condition is so simple that we may 

 almost regard it as normal. Consequently, treatment of 

 any kind is superfluous. Where constitutional disturbance 

 is exerting an influence upon either the quality or quantity 

 of the blood directed to the part, then, of course, attention 

 must be paid to the disease from which it is arising. 



F. THE HOOF WITH BAD HOEN. 



(a) The Brittle Hoof. 



Detinition. — As the name indicates, w'e have in this con- 

 dition an abnormally dry state of the horn. 



Symptoms. — These are obvious. The horn is hard, and 

 when cut by the farrier's tools gives the impression of 

 being baked hard and stony, the natural polish of the 

 external layer is wanting, and there is present, usually, a 

 tendency to contracted heels. With the dryness is a 

 liability to fracture, especially at points where the shoe is 

 attached by the nails. As a consequence, the shoes are 

 easily cast, leading to splits in the direction of the horn 

 fibres. These run dangerously near the sensitive struc- 

 tures, giving rise in many cases to lameness. Even where 

 pronounced lameness is absent the action becomes short 



