Chapter XXII. 



DISEASES OF THE BONES. 



THE skeleton of a horse is made up of 242 bones ; and as these 

 bones are the hard frame-work' of theanimal body, serving for 

 the support and attachment of the softer textures and the pro- 

 tection of delicate organs, they are consequently liable to the same 

 accidents and diseases as the other parts of -the body. They are 

 composed of animal and earthy matters, in the proportion of one 

 third of the former to two thirds of the latter. They are covered 

 externally by a sensitive and vascular membrane called the perios- 

 teum, and lined internally byia similar membrane called the en- 

 dosteum. They enter into the formation of the joints, their ends 

 being held together by the ligaments, and their adjoining surfaces, 

 being 1 'covered by cartilage or gristle, with a lubricating fluid be- 

 tween, called synovia, or joint-oil, to preventQfriction and facilitate 

 the motion of the joint. 



Diseases of the bones are not very numerous in the lower ani- 

 mals ; the most common are Exostosis, in which we have an en- 

 largement or bony tumor thrown out on the surface of the bone ; 

 when between two bones, and uniting them together^ it is called 

 Anchylosis Caries, generally defined to be an ulceration or disinte- 

 gration of the bony texture ; Necrosis, which is the entire .death of 

 the whole of part of a bone ; Osteosarcoma, which is a disease more 

 particularly of ftie ox tribe, in which we have a tumor on the bone, 

 partly bony and partly fleshy, occurring commonly on jaws or ribs ; 

 and Enchonctroma, consisting of a cartilaginous or gristly tumor on 

 a bone ; it is more common in, man, but is also seen in cattle, and 

 occasionally in the horse. 



Anchylosis of Bone. 



Anchylosis is simply extensive exostosis, in which we have the 

 ends of two or more bones united by bony matter, as shown in ring- 

 bone, spavin, splint, etc., 



Symptoms are enlargements round the joint, which is stiff and 

 inflexible, and in dome cases the animal is lame. 



Treatment. — If there is lameness, blister or fire, as may ,be 



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