so harmless indeed, as periosteotomy ; all that we have to desire 
is that it were more generally successful than in practice it is 
found to be. Were the pain, the cause of the lameness, the pro- 
duct of distention alone of the periosteum, we might place great 
reliance on periosteotomy ; but, when we know that the callus of 
the exostosis is a nidus of inflammation, and, consequently, a 
source of pain in itself, we lose confidence in an operation which 
effects no more than the relief of the membrane covering the 
tumour. This constitutes the principal cause — there being other 
minor causes — of the failure of periosteotomy in pure exostosis. 
To the articular disease of spavin it is, of course, altogether 
inapplicable. 
Were spavin nought but exostosis, there would be nothing in 
the way of the horse’s restoration to soundness ; the inflammation 
and pain attendant for a longer or shorter time on the callous or 
osseous tumour being relievable in a variety of ways, though by 
some more promptly and effectually than by others ; whence have 
arisen the number and diversity of remedies proposed or practised 
at one time or other for spavin. The disease within the joint, not 
being known, was left out of the account of treatment. Defective 
pathology has led to insufficient or erroneous therapeutics; and, 
strange to add, even now that the former is amended, the latter 
still remains unimproved. 
Counter- IRRITATION will be found to be the leading prin- 
ciple on which the treatment of spavin has hitherto been, con- 
ducted, and it is a principle in entire accordance with the new 
lights thrown upon the pathology of the disease, and one on which 
we are still mainly if not exclusively acting in our therapeutics : at 
the same time we have a right — nay, it is our bounden duty — to 
inquire whether or not counter-irritation includes every therapeutic 
agent of use to us in our attempts to remove or relieve the lame- 
ness arising from spavin. We must bear in mind that spavin, 
which has hitherto been treated as consisting simply in exostosis, 
has to be regarded by us as a disease of the synovial membrane 
and articular cartilages, and, further, that it is to the breeding 
rather than to the development of the disease that our efforts must 
be directed, if we would hope for a favourable result. I hesitate 
not to assert that great error, under delusion of external appear- 
ances, has been committed in the ordinary modes of treating spavin ; 
and to add, that it is high time this error, so serious to our 
patients and discreditable to ourselves, should be corrected. 
