STRING-HALT-ITS DOUBTFUL PATHOLOGY. 591 
it to be a muscular affection mistake, I conceive, the 
effect for the cause. I choose rather to refer its seat to the 
spinal marrow, or to the nervous trunks passing between it 
and the affected muscle.'’^ This quotation undoubtedly shows 
that Mr. Percival considered the excessive muscular action 
in this affection was due to undue excitation of the nerves 
that supply the muscles implicated, and he endeavours to illus¬ 
trate this by alluding to a case of fracture of the back, the 
effects of which, in his opinion, caused irritation of the roots 
of the motor nerves at their junction with the spinal marrow. 
' These views coincide with those of Professor Spooner, and 
which can be shown, as far as they go, to be correct: at 
least such is my opinion. Again, in the same work, and on 
the same page, is a short extract from an article in the 
Veterinarian of 1829, by Mr. W. Goodwin, on the cause of 
string-halt, in one particular case only. The horse he refers 
to was destroyed in consequence of some accident, but from 
his haGng been the subject of string-halt care was taken to 
examine him post-mortenij especially in reference to the cause 
of this affection, and it was found that his dorsal vertebrae 
were partially anchylosed, and the spinal canal diminished 
thereby in size. Now, although Mr. Goodwin might have 
considered the diseased state of the vertebrae in this case to 
have been the cause of string-halt, still we have no right to 
suppose that he did not consider it could be produced by 
other causes. 
With reference to the late Mr. Youatt, I am not aware 
that he ever advanced any special opinions of his own re¬ 
specting the cause of string-halt, but simply compiled the 
opinions of others. 
Having thus briefly considered the views, as far as the 
published accounts go, of Messrs. Spooner, Percivall, and 
Goodwin, on this subject, I will next take a glance at 
those propounded by Dr. Busteed as to the cause of the 
affection. It appears that, after dissecting the hocks of 
several horses known to have been affected with this malady, 
in some instances for several years, he came to the con¬ 
clusion that it was produced by an ulcer on the upper ar¬ 
ticular surface of the astragalus, which, by irritating the 
nerves of the limb, caused a spasmodic contraction of the 
muscles, but he does not say which nerve is irritated, or what 
muscles are influenced, by such irritation. On the other hand. 
Professor Spooner expressly states that it is the sciatic nerve 
which is involved in the production of the phenomenon, and 
that the irritating agent, whatever it is, may exist at any 
part of the nerve. 
