•298 BOG SPAVIN. 



its smooth glistening surface to lose its transparency — to become, 

 first opaque, then deadly yellow in aspect, and, finally, to present 

 a surface uneven, rugged even, in consequence of being studded 

 with exudations of coagulable lymph in a state more or less ad- 

 vanced towards assimilation to the altered condition of the mem- 

 brane itself. Sometimes, in a more advanced stage of disease still, 

 the membrane exhibits a sort of fibrous or reticular character, 

 having running over its surface slender bands or cords of consider- 

 able toughness, disposed after a manner to form so many little 

 meshes or pouches upon the membrane. Within the cavity of one 

 bog-spavined joint we examined, lodged in the upper and posterior 

 compartment of it, we found a small parti-coloured ovoid body, in 

 appearance not unlike the pineal gland of the brain, though not 

 above half its magnitude, secured in its situation by slender cords 

 of the same description as those first mentioned. The substance 

 being cut in half, nought was found within it but some loose soft 

 tissue resembling a mass of condensed cellular membrane. 



In some comparatively rare instances the thickened capsule of 

 the joint, after the continuance of bog spavin for some length of 

 time, becomes slowly converted into a solid and hard substance of 

 the nature of callus or cartilage, and this, in the progress of the 

 morbid action, changes into osseous substance; transformations 

 which, as we have seen, Mr. Pritchard regards as taking place in 

 the secreted fluid of the joint. This ossific action may, however, 

 not confine itself to the region of bog spavin, but may extend over 

 contiguous parts, and at last grow into a large spreading ugly tu- 

 mour upon the inner side of the hock joint. 



Bog Spavin is not productive of Lameness so long as it 

 maintains its ordinary form, or, in other words, so long as it con- 

 sists merely in accumulated secretion and thickened capsule. Nor, 

 in general, is there any reason to apprehend any thing further. 

 Still, every now and then do we meet with cases in which bog 

 spavin is growing into or has already become a formidable disease. 

 Inflammatory action appears to be set up in the capsule of the 

 joint ; and those changes in the lining of the capsule, and in its 

 secretion, which have been already detailed, supervening, the 

 disease presents itself to us in the form of a tumour upon the 



