DISEASES. 665 



place of separation thoroughly with the drawing knife, and to fiU 

 the space with a putty of gutta percha. 



Diseases oi' the Frog. 



This part of the horse's foot is exposed to many pathological 

 lesions. Some are merely accidental, and result from the intro- 

 duction into its structure of nails, and other various foreign 

 bodies, more or less sharp, which the animal picks up in walking 

 or performing his work. We have already considered these forms 

 of lesion in the article upon punctured wounds. The frog is 

 often bruised, a lesion which may be followed by a complication 

 which we may be allowed to consider under the name of furuncle 

 of the frog. But besides this, some special diseases are also ob- 

 served, among them one already known to us under the name of 

 canker, and another which is more commonly known under that 

 of thrushes. 



(A) Theushes. — This affection is often, but wrongly, considered 

 as the beginning of canker, being characterized by the presence 

 of a puriform secretion, blackened and very foetid, which collects 

 and accumulates in the lacunae and excavations of the frog, 

 whether in its middle or upon its sides. There is often an in- 

 creased sensibility of the parts, which in some cases may give 

 rise to very serious lameness, preventing the animal from stand- 

 ing, and rendering the movement of walking very painful. The 

 horn of the frog often becomes soft and thready, when the frog is 

 called rotten, and the softness increases until it drops off by piece- 

 meal. 



The causes of this affection are, first, excessive work on stony 

 roads ; changes from excessive dryness to moisture ; the strong 

 muds of streets, and standing in damp and dirty places, especially 

 in urine and manure, as is often the case in badly kept stables. 

 But there are horses whose feet are also affected with thrushes 

 even when standing on a dry bedding ; those whose feet are con- 

 tracted ; and again, weU-bred horses with good frogs, and in which 

 there is a constitutional tendency to that condition of the horny 

 structures. 



The treatment consists in avoiding aU known causes likely to 

 give rise to this morbid condition of the frog. Sometimes the 

 foot must be pared, and all the parts where the puriform secretion 



