172 DISEASES OP THE HOBfiB. 



Periosteum. — The thin pearly covering investing the 

 bone. It is the stretch of this membrane in cases of splint 

 which causes pain and lameness. (See Splint.) 



Fhagadena. — A name used in surgery, implying a 

 spreading and destructive ulcer, which spreads rapidly and 

 destroys the surrounding parts. The true meaning of this 

 word is eating, and in its eifects it is similar to what is 

 called, in domestic practice, hospital gangrene — a local, 

 spontaneous combustion, in which oil globules are poured 

 out in great quantity in and around the sore or ulcer. 

 These ulcers are common on the heels and legs of horses 

 after a severe winter. When on the heels, the ulcers are 

 taken by horsemen to be scratches. Phagadena does not 

 usually assume the form or appearance of a cut or scratch, 

 but is generally a flat, round or oval, and circumscribed 

 sore at first; the hair of the part stands on end, with 

 oil drops all over the surface, and in a few days the whole 

 of the skin and hair falls oif, or a separation of the edges 

 of the sore will take place, and the skin and flesh of the 

 part will completely fall out, (called core) leaving an un- 

 healthy looking sore, with a white sanious fluid covering 

 the whole of its surface. When the slough does not take 

 place, it is gradually eaten away, and in this case leaves 

 Cxi the edges and surface of the sore a thin dirty colored 

 looking skin or membrane. 



Causes. Bad habit of body, from impure o ood, death of 

 the part from exposure of the heels in some mixture of salt 

 and snow. Cold drafts under stable doors. 



Treatment. The complete removal of all dead matter 

 belonging to the ulcer, and a thorough cleansing of its 

 inner surface. This is important, as it will not only be 

 rendered necessary as a measure of cure, but as a surety 

 against it spreading further up the leg or heels. Then 



