CAUSE OF SPLINTS. 
587 
complete, pain and lameness generally disappear, though the splint 
itself remains as a blemish. In many cases, however, especially in 
young horses, severe work is again and again followed by lameness, 
causing the disease to persist for a long time. The mature exostosis 
gradually diminishes, sometimes by becoming flattened, sometimes by 
the neighbouring bone becoming thickened, and under certain circum¬ 
stances may so far recede as to require a careful examination to detect 
it. The late H. G. Eogers drew attention to the frequent occurrence of 
exostoses on the metatarsal bones, and suggested the possibility of their 
causing lameness. Though they undoubtedly do so in occasional cases, 
as Dollar has convinced himself, the proportion of such cases is 
probably small. 
The cause of periostitis consists in traumatic irritation of the inter¬ 
osseous ligament, periosteum, and bones. On account of their almost 
invariably occurring on the inner side, the view was once held that 
splints were produced by striking. Havemann was the first to expose 
this error, and to point out the longish shape of the splint, and the 
fact that injury of the skin is very rare. He directed attention to the 
construction of the carpus, and especially to the position of the small 
trapezoid bone (os multangulum minus horn.), and viewed this as a 
cause of the disease. Whilst on the outside the unciform (os hamatum 
horn.) rests partly on the outer small splint bone, partly on the 
metacarpal bone, on the inside the small trapezoid rests almost entirely 
on the inner small splint bone. This explains why faulty action or 
unequal distribution of pressure in the knee may throw an excessive 
load on the inner small metacarpal, and cause ruptures in the inter¬ 
osseous ligament fixing the small to the large metacarpal. The 
incomplete union between the bones in young animals explains the 
frequent occurrence of splints during early life. At a later period 
union is ossific, and the disease therefore seldom occurs. 
This explanation of Havemann’s was generally viewed as correct, until 
recently Dieckerhoff raised a doubt about it, and stated that the disease of 
the periosteum was produced by the pull of the fascia of the fore arm. He 
describes splints so produced as “spontaneous,” in contra-distinction to those 
caused by blows, which he terms “traumatic.” The lower insertion of the 
fascia of the fore arm is partly into the metacarpal bones, especially the inner 
small metacarpal, partly into the subcutaneous connective tissue. Ruptures 
of it, and especially of its point of insertion into the bone, are said by 
Dieckerhoff to give rise to disease in the subfascial connective tissue, which 
disease extends to the periosteum. The facts adduced by Dieckerhoff in 
support of this modification of Havemann’s view seem insufficient, and by 
no means conclusive. There is much evidence in support of Havemann’s 
showing. The disease generally begins in the interosseous ligament, 
between the small and large metacarpal bones, whilst no disease processes 
of any kind can be detected in the fascia. Nor can cedematous swelling of 
the subcutis be regarded as an infallible sign of the condition referred to, 
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