126 EXAMINATION OF HORSES 
alike. I shall explain this operation that you may know 
‘how to perform it, and by that means learn to detect the 
appearance a hock presents after it has been successfully 
accomplished. The operation is neither more nor less 
‘than a vowel placed over the seat of spavin in a neat way, 
but goes by the name of ‘*causticking.” It was, I be- 
lieve, performed first, and I know very extensively, by the 
late Mr. Fryer, of Kirkby Fleetham, in Yorkshire, who 
got such areputation in the performance of this operation: 
that his services were sought farand near. The “caustic” 
he used, so far as I know, was never made known even 
to his profession, but I have always used a simple 
digestive made of equal parts of oil of cantharides, oil of 
turpentine, and oil of thyme. After the horse has been 
cast and secured properly, an incision through the skin 
and cellular tissue only is made, about an inch in length, in 
the long axis of the limb, about an inch and a half behind 
the spavin place, and an inch delow this again. You then 
take a probe-pointed seton needle, and push it upwards 
and forwards, and sweep it all over the site of spavin, 
taking care in doing so that your needle is well under the 
cellular tissue as well as the skin, because, as you know, 
the cellular tissue contains the blood-vessels and nerves 
which nourish the skin and holds the same relation to 
the skin that the periosteum does to bone, and therefore, 
as the bone beneath the stripped-off periosteum must die, 
so does the skin separated from its cellular tissue. Take 
care then in doing this operation not to fall into such an 
error, or a “slough” of the skin may result. Having 
