SPAVIN. 
727 
lamenesses. In judging of this, it should he borne in mind that English 
thoroughbreds not infrequently show asymmetry in the breadth of the 
two sides of the pelvis which might easily mislead the observer. 
Eberlein also states having been able to demonstrate atrophy of the 
diseased hock by actual measurements. The upper parts of the affected 
joint were sometimes 2 inches less in diameter than that of the sound 
limb. Even at the level of the exostosis (spavin) the measurement was 
lessened. Eberlein regards this as due to inaction—atrophy. 
The visible changes on its exterior usually show whether the joint is 
or has been diseased, but alone are not proof that the existent lameness 
is due to spavin, for very frequently the lameness disappears after 
anchylosis of the joint, though other conditions may interfere with the 
movement of the limb. To refer such lameness to the changes in the 
hock-joint would be a serious error. The diagnosis “ spavin lameness ” 
is only justified when— 
(1) The local changes are accompanied by lameness, the course and 
other peculiarities of which agree with the description above given. 
(2) Muscular atrophy or other condition points to old-standing- 
lameness, probably connected with the anatomical changes. As already 
stated, exostoses are more likely to cause lameness the nearer they lie 
to the front of the joint. Sometimes traces of past treatment are visible, 
pointing to a chronic condition, and supporting the diagnosis “ spavin.” 
Acute inflammatory symptoms, increased warmth, pain on pressure, 
&c., are seldom seen unless the condition has resulted from violence, 
but their presence is not incompatible with spavin lameness. 
Differential diagnosis. By bearing in mind the above-mentioned 
principles, mistakes will usually be avoided, though the following- 
conditions present many points of resemblance to the lameness now 
under consideration :— 
(1) Stringhalt, a disease which will be described in another place. 
Here it need only be remarked that the periodical appearance and 
gradual abatement of lameness during work point to spavin. 
(2) Hip lameness. In these cases lameness is only marked when the 
limb is carried (swinging-leg lameness), whilst in spavin it exists both 
when the limb is carried and when weight is placed on it. The same 
applies to— 
(8) Gonitis chronica, in which also there is a marked tendency to 
stand with the limb flexed (see “ Chronic Inflammation of the Stifle- 
joint ”). 
(4) Inflammation of the tendon sheath of the flexor pedis at the inner 
surface of the hock-joint. This, however, can scarcely be mistaken for 
spavin, on account of the marked swelling (see “ Diseases of the 
Metatarsus ”). 
