DISEASES OF THE METACAKPUS. 
560 
enlargement, allowing its contents to be discharged. More or less severe 
inflammation results, and recovery may possibly follow. As the point 
of operation itself is sterilised and an aseptic wound produced which 
soon closes by inflammatory swelling, opening by the actual cautery is 
less dangerous than by the knife, but the effect is not always reliable. 
When the exact degree of inflammation necessary to prevent after¬ 
secretion of fluid is produced, a cure may result, but this degree is very 
difficult—indeed, usually impossible—to secure at will. 
The same criticism applies to drainage of synovial sacs. This treat¬ 
ment consists in puncturing'the enlargement at the highest point, passing 
a director and making a counter-opening at the lowest point, inserting a 
drainage-tube, and irrigating the sac with 1 in 1,000 sublimate solution. 
Active inflammation follows and persists for three or four weeks. In 
favourable cases, the endothelial lining of the sac, though at first 
replaced by granulations, is said to be restored. The treatment has 
hitherto been confined to enlargements of the extensor sheaths in front 
of the knee, hock, and fetlock. 
To sum up : enlarged synovial cavities should at first be treated by 
rest, cold applications, massage and compression. If they cause lame¬ 
ness a blister can be tried; in the event of this failing the parts are fired 
in lines or points, or the swelling may be punctured with the cautery 
and the contents evacuated, but only with full antiseptic precautions. 
For enlargements of old standing which resist other forms of treatment 
and cause permanent lameness neurectomy may be performed. 
D. DISEASES OF THE METACARPUS . 
The metacarpus in solipeds consists of the so-called os metacarpi tertium, 
the cannon bone, and the two small metacarpals. The tendons of the 
extensores pedis et suffraginis cover its anterior surface ; behind it lie the two 
flexor tendons, to some extent enclosed by the two small metacarpals. The 
whole metacarpus is covered with a tensely-stretched skin, which is only 
slightly movable on the underlying parts. 
In ruminants the two cannon bones become united soon after birth and 
form only one bone, on whose posterior and outer surface lies the rudimentary 
small metacarpal, which is articulated to the fused metacarpal by means of a 
small joint. This rudimentary metacarpal does not contribute to the formation 
of the knee. 
In swine the two middle or true cannon bones form, with the external or 
false metacarpals, the metacarpus. Carnivorous animals possess five meta¬ 
carpals, those of the third and fourth toes being the strongest. 
These peculiarities in the formation of the metacarpus cause considerable 
diversity in local disease processes in the different species of animals. 
Especially is this true of fractures. 
