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Thorough-Pin. 



A Thorough-pin may be defined to be, a windgall running 

 from side to side through the upper and back part of the hock. 



The Name of " Thorough-pin " owes its derivation to this 

 " running through" or thorough; it being originally taken from the 

 French vessignon chevilUy which means precisely the same thing 

 as our through or thorough-pin. 



The Site of Thorough-pin is notorious enough. It occupies 

 the floor of the hollow interval at the supero-posterior part of the 

 hock, between the joint in front and the tendo Achillis behind ; 

 reposing, as it were, after the manner of a cushion placed trans- 

 versely upon the joint beneath. 



Felt on either side, it has all the sensible characters of 

 windgall ; and the fluid it contains is readily made, by pressure or 

 pulsation with the fingers, to fluctuate from one tumour to the other, 

 shewing that free communication exists between them. In fact, to 

 external examination the swellings appear as though an oblong 

 bladder or windgall had become formed here, and that it was com- 

 pressed or nipped together in the middle by some narrow pass it 

 had to permeate. 



This is the ordinary but not invariable seat of thorough-pin ; 

 for, on occasions, the tumours exhibit a more spread-out aspect, 

 and are broad or even diffuse instead of being spheroid or ovoid 

 and circumscribed, and so extend downward upon the sides of the 

 hock; though this latter is a remark more applicable to the tume- 

 faction upon the outer side. 



The Tumour is not necessarily Thorough, or chevilU. 

 Sometimes it is confined to one side ; and more frequently, we 

 believe, in this single form, will the swelling be found outward 

 than inward. Such cannot, strictly speaking, be called thorough- 

 pin, although in nature the tumour nothing differs from it. When 

 true thorough-pin is present, however, the inner tumour is gene- 

 rally the larger or the more prominent of the two. 



True Thorough-pin is rarely or never seen without 

 Bog Spavin, although bog spavin, in the majority of instances, is 



