Fig. 20.—Suppurative arthritis following traumatic osteo-periostitis.
Treatment. Should the patient be in reasonably good condition, but otherwise of no particular value, it should at once be slaughtered. If, on the other hand, it possess a special value, and the owner wish to preserve its life, the same antiseptic treatment should be adopted as was indicated in dealing with suppurating synovitis of tendon sheaths. The loss of the articular cartilage of the joint is followed by free granulation and union of the apposed surfaces of bone resulting in anchylosis of the joint and qualified recovery. Such results, however, are only likely to follow in relatively light animals which are capable of standing for considerable periods.
II.—STRAINS OF JOINTS.
When, in consequence of muscular contraction or external violence, the bony surfaces constituting a joint are displaced so as to stretch, lacerate, or partially tear the ligaments, synovial capsule or tendons supporting the joint, so-called sprain, or strain, or wrench results. The articular surfaces are not sufficiently displaced to cause luxation, but a series of periarticular injuries result, and are followed by the symptoms which we recognise as those of strain. Joints in which movement is restricted within narrow limits, such as the hock or fetlock, are most liable to such injuries, which also occur in very freely movable articulations like the shoulder and stifle.
STRAIN OF THE SHOULDER.
This accident is produced by the animal falling on its side, by slipping at the moment of landing, the limb being extended and in contact with the ground, by the foot slipping at the moment when it is leaving the ground and the limb is at its extreme limit of backward extension, by side slips, etc. The periarticular lesions will then be found on the front, back, or internal surface of the articulation, depending on the manner in which the accident has occurred. According to some authors, violent muscular efforts, as well as work in soft clay soil, bogs and rice swamps, are also capable of causing strain of the shoulder.
Symptoms. At first moving appears difficult, the patient lies down a great deal, then lameness becomes characteristic. Movement of the scapulo-humeral joint being painful, the patient endeavours as far as possible to avoid it; the limb is advanced stiffly in an abducted position and with a mowing movement. This semi-circular movement avoids the necessity of flexing the scapulo-humeral angle, but diminishes the length of the stride.
Locally, the region of the scapulo-humeral angle is swollen, doughy, and extremely sensitive on manual examination. If the practitioner endeavours to flex it by lifting the limb the animal flinches.
Diagnosis. The diagnosis is not very difficult, although the peculiar mowing movement is also seen in other cases, such as cracked heels and mallenders.