214 HEALTH AND DISEASE 



discharge and refuses to heal. It becomes necessary, therefore, that a 

 periodical examination of the diseased part should be made, in order 

 that the earliest ojjportunity may be seized to extract the offending 

 matter. For this purpose it may be necessary to lay the wound open. 

 This done the finger should be introduced, and the necrosed mass will 

 be found probably grown o^•er by granulations or " proud flesh ", or at 

 least united by them to the body of the bone. If detachment has not 

 been completely effected a little force, by means of a small lever placed 

 under the dead fragment, may be sufficient to disconnect it. 



The dead bone having been remo\'ed the wound may be freely dressed 

 with a strong solution of chloride of zinc, and afterwards treated with 

 antiseptic applications until reparation is complete. 



OSTEO-POROSIS— BIG HEAD 



By this term is understood a swollen, soft, and porous state of the 

 bones. It is a constitutional disease usually involving the entire skeleton, 

 but manifesting itself with much greater severity in some parts than in 

 others. This is especially the case with regard to the head, from which 

 circumstance it has received the common appellation of " big head ". 



Not only is this difference observed in different regions of the 

 skeleton, but likewise in different parts of particular bones. In the 

 long bones of the legs, for example, it becomes much more pronounced 

 at the extremities where they unite to form joints, and where, as in the 

 bones of the face, the osseous tissue is naturally of a loose, spongy 

 character (cancellated). 



Osteo - porosis is essentially a chronic and slowly progressive disease 

 affecting all classes of horses, both male and female, and at all periods of 

 life, but young animals seem to be more predisposed to it than those 

 advanced in years. 



It has not been found to exist to any considerable extent in Great 

 Britain, but in America, India, and Africa it is of more frequent occurrence. 



Origin. — Although much has been written both in this country and on 

 the Continent with regard to its origin, the writer is compelled to admit 

 that practically nothing is known as to the causes which give rise to it. 

 Captain Hayes, who refers to numerous cases as coming within his experi- 

 ence in Africa and India, believes that "feeding on unnutritious grasses 

 is one of the chief causes of the malady". This statement, however, 

 receives no support from experience in this country, where the cases 

 hitherto recorded have been stabled animals receiving a liberal supply of 

 good food. By others it has been attributed to damp and insanitary 



