66 



DISEASES OF THE SYNOVIAL MEMBRANES AND ARTICULATIONS. 



difficult. The condition can only be confused with distension of the 

 synovial sheath of the extensor metacarpi magnus ; but this (synovial) 

 swelling extends in the same direction as the tendon, i.e., vertically, 

 attains the lower third of the radius, and is broadest above. Hygromas 

 must also be distinguished from tumours. Moussu only mentions a 

 single case of this kind, the tumour being very slightly bosselated and, 

 naturally, revealing no fluctuation. 



The prognosis is not grave, though the condition may prove trouble- 

 some, because the original injuries may be continued even during treat- 

 ment and prevent recovery. 



Treatment. Success rarely follows 

 cold applications or blistering, which 

 are only of value at the commence- 

 ment. It is better to puncture the 

 cavity aseptically, remove the fluid 

 contents, and fire the growth in points. 

 Free opening of the lowest portion of 

 the swelling is followed by discharge 

 of liquid, but almost inevitably by in- 

 fection at a later stage, and by suppu- 

 ration. Eecovery certainly may occur, 

 a slight thickening of the anterior 

 surface of the knee remaining; but 

 the process is often very prolonged. 

 Some authors prefer to pass a seton or 

 drain vertically through the swelling. 

 The results are identical with those 

 following free oi)ening and drainage, 

 suppuration being unavoidable. 



If the animal be sufficiently valu- 

 able to warrant surgical intervention, 

 the entire hygroma, together with its 

 indurated wall, may be excised. An 

 elliptical fragment of skin is removed from the front of the swelling, and 

 the whole mass separated by dissecting away or tearing through the connec- 

 tive tissue. Considerable care is necessary to avoid injuring the synovial 

 sheaths of the extensor tendons. This treatment, which is only applicable 

 in valuable animals, is completed by firmly suturing the lips of the wound, 

 and applying an antiseptic surgical dressing or a plaster bandage similar 

 to that used in operating on broken knees in horses.* The animal must 

 be prevented from lying down until the wound has firmly united. 



* See Dollar's "A Surgical Operating Table for the Horse." (London: Gay 

 and Bird.) 



Fig. 26. — Hygroma of the knee. The 

 skin has undergone conversion into 

 a substance resembling horn. 



