184 
SPAVIN. 
nay, the very main joint of the hock itself is threatened with 
anchylosis. I have also seen instances — and in the different 
veterinary museums exist preparations oh the kind — in which the 
articulatory mechanism of the hock has been encrusted and ren- 
dered entirely immovable by a complete coating of exostosis. In 
general, ho'wever, the ossification is confined to the two cushion 
bones, they commonly being the first to contract bony union ; next 
to them, the articulation between the lower cushion bone and the 
large metatarsal appears to suffer ; lastly, that between the upper 
cushion bone and the astragalus. 
Ready-formed Spavin attended With Lameness being 
the case usually presented to our notice, it becomes of importance 
that we should, as well as we can from observation and experi- 
ence, make ourselves acquainted with the rationale of a case so 
common. Supposing it to be a first attack and a recent one, the 
owner of the horse representing that he has never been lame of the 
limb previously, it is of some consequence to know whether there 
had occurred any precedence in the appearance of the tumour and 
the lameness, also the period of time which one or both had taken 
to discover themselves. My own experience inclines me to the 
belief that in most cases the tumour of spavin is preceded by lame- 
ness : either the horse has been noticed to limp a little in first 
stepping out of his stable, or to go stiffly with the limb in action, 
or else to move in his stall stiffly upon it, or to rest it in preference 
to the opposite limb. One of two things seems certain in these 
cases; either that the tumour, if of slow growth, has occasioned 
the animal little pain or inconvenience while forming, or that the 
exostosis, keeping pace with the progress of the lameness, has been 
of rapid growth : of which alternatives I am disposed to adopt the 
latter, and for reasons that will best appear in the annexed case, 
one selected from others whereon observations made had proved 
similar : — 
In July 1841, Captain B requested me to look at his 
second charger, the animal having gone, as he said, “ very lame 
behind, the day before, while being ridden out.” I examined the 
horse, but could detect no lameness whatever, although the trial trot, 
and sudden pull up, and turn-about, were several times repeated; 
neither did there appear any thing about the limbs to argue the 
presence of lameness. I therefore sent the horse back into his 
stable, with a message to his master to the purport that he must 
have “ fancied” his horse lame, for I could discover no lameness 
about him. In the course of conversation, however, on the sub- 
ject, the day following, the Captain persisted his horse had gone 
palpably lame, although he afterwards admitted that the lameness 
had disappeared in the course of his ride. Four days after this, 
