216 



HEALTH AND DISEASE 



at tlie same time to become spongy and soft, so much so in some parts as to 

 yield to the pressure of the fingers from without. When in this condition 

 the animal has difficulty in rising, and the ligaments of the joints soon fail 

 to resist the weight imposed upon them, and bi-eak from their connections 

 with the soft and yielding bones. 



In the early stages of the disorder the turning- 

 movements are noticeably stiff, and pressure, if 

 applied to the spine, causes pain and shrinking. 

 The head continues to increase in size and 

 to present an unsightly appearance. The lower 

 jaw becomes thick and rounded, and as the bones 

 of the face enlarge, the teeth become loose in their 

 sockets and more or less displaced. At this time 

 mastication is imperfectly performed, nutrition is 

 impaired, and symptoms of constitutional derange- 

 ment appear and continue to become more and 

 more severe to the end. In f;ital cases the dura- 

 tion of the disease extends from two to eioht 

 months or lonoer. 



Treatment. — Osteo-porcsis is usually ffxtal. 

 It is worthy of note, however, that a case given 

 up to the writer was returned cured after under- 

 going three courses of iodide of potassium and 

 nux vomica at intervals of three or four weeks. 



Post-mortem Examination. — After death 



no special lesions are found to exist in the ab- 

 dominal or thoracic viscera. Many or all the 

 bones of the skeleton are enlarged (fig. 323), 

 spongy in texture, and soft in consistence. 



The capsular membranes of the joints of the 

 extremities are much thickened, and the articular 



ends of the bones are denuded of their cartilage, and present a worm-eaten 



appearance. 



SPAVIN 



Fig. 323.— Osteo-porosis 



Metacarpals of horse affected by 

 the disease. 



The term spavin is applied to two distinct forms of enlargement of 

 the hock, one being a bony excrescence (bone-spavin), and the other a 

 distension of the joint capsule with fluid (bog-spavin). Spavin is also 

 spoken of as occult when the action declares the hock to be the seat of 

 mischief in the absence of any outward physical change. Bog-spavin is 

 dealt with in the section on Diseases of Joints. 



