Williams, Fisher, and Udall: The Spavin Group. 41 
the stride. Generally the undefined stiffness develops more or 
less rapidly into distinct lameness of varying severity, which 
is frequently masked in a measure by its symmetrical character, 
the two limbs becoming simultaneously affected in the corre- 
sponding joint. The lameness generally tends to decrease. dur- 
ing moderate exercise, and in spavin especially may wholly dis-) 
appear. Severe work, either at a rapid pace or heavy draft,| 
increases the lameness, and this becomes still further accentu- 
ated if after a period of hard labor the animal is kept closely 
confined for some hours. ; 
In severe cases the lameness increases more or less rapidly 
in intensity, the number of joints involved tend to increase, the 
spinal column becomes rigid, and the animal has difficulty in 
getting up when down, or, after experiencing difficulty, avoids 
lying down and sleeps in the standing posture. 
At times the lameness is very sudden. Perhaps a ringbone 
or spavin has long existed without lameness, when suddenly,, 
with or without known accident, the animal becomes severely, 
lame, perhaps as the result of a fracture between two imper- 
fectly anchylosed bones, or, as in a case observed by us (W.), 
what appeared to be a fracture of the navicular bone, like in * 
Fig. XIX, occurred during a journey, the animal starting appar- 
ently sound, returning later severely lame in one foot from 
navicular disease, lameness quickly following in the other foot 
and continuing in both until neurotomy became necessary. 
In ‘other cases one of the phalanges becomes cracked without 
adequate reasons aside from the diseased condition, as shown at 
3 in Fig. I, As a general rule, there is no history of trau- 
matism, and in many cases where mechanical injury is alleged 
-the evidence is by no means convincing. 
The local manifestation of disease may precede, accompany, 
er follow the advent of lameness. These consist of the cardinal 4 
symptoms of inflammation, any one of which may be wanting. 
In extensive joints with large synovial sacs, there is usually 
an increase of synovial fluid:::. This is notable in gonitis, and 
constitutes the chief visible change in the joint. In sesamoi- 
ditis it is well marked, and in navicular disease the bursa is 
sometimes so distended as to show in the heel. . In spavin, the 
tibio-astragaloid bursa is frequently distended, serving as a mask 
for the more definite exostoses of the lesser bones. While 
authors describe this group as dry arthritis, it seems to us that 
4 
