69 
LAMENESS IN HORSES. 
By William Percivall, M.R.C.S. and V.S. 
[Continued from p. 5.] 
Bog Spavin. 
This is a misnomer for the disease we are about to consider. 
Contrary to what might be expected, it has no relation whatever 
to SPAVIN, properly so called; but has acquired the same appella¬ 
tion, as it would appear, simply from the circumstance of its being 
a swelling occupying pretty nearly the same situation : the epithet 
“ bog,” meaning something that bends or yields , being prefixed as 
the antithesis of bone spavin, which is a tumour hard and unyield¬ 
ing. 
A Bog Spavin may be defined to be, a soft, elastic, fluc¬ 
tuating tumour, of the nature of windgall, growing upon the inner 
and anterior part of the hock joint. 
The Magnitude and Form of the Tumour are, ordinarily, 
that of the section of an orange, small or large, and prominent, 
according to circumstances. 
The Site of the Tumour is the anterior and inner part of the 
hock joint, in the interval between the malleolar projections of 
the tibia, above and more anteriorly than the situation of (bone) 
spavin. 
The Differences between Bog and Bone Spavins are, 
therefore, obvious. Their sites are not the same, their consist¬ 
encies are different; one being soft, the other hard. And the 
tumour of bog spavin is broad and extended, while that of bone 
spavin is comparatively small, and is circumscribed. Other differ¬ 
ences of a more important character there are, pathological and 
consequential, which will become developed as we proceed. 
The Causes of Bog Spavin are such as produce windgall in 
general ; to which may be added such as in a peculiar manner or 
degree operate upon the hock. They may be regarded as divisi¬ 
ble into general and local. Febrile, rheumatic, and general dropsi¬ 
cal or cedematous affections, will be likely to be attended with 
augmented secretion of synovia in the joints of the body in gene¬ 
ral, and in an especial manner of the hock. But the hock being 
the joint on which so much depends in progression, any excessive 
work the animal may be made to perform, or excessive weight he 
may be forced to carry, will in a peculiar degree tend to stretch, 
strain, or disorder this joint; so that, while the fetlock joints are 
the parts upon which work or concussion tell in the fore limb, the 
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