Appetite is normal or only diminished. The pain continues, and causes progressive wasting and diminution in the yield of milk.
If at this time the practitioner makes a careful digital examination of the diseased region, he may find one of two conditions. In the first, the synovial sacs appear distended, fluctuating and in exactly the same condition as in ordinary bog spavin. This is what has been termed the exudative form of infectious arthritis. In the second, the enlarged joint remains very sensitive, the walls of the synovial sac are thickened, fluctuation is either absent or only slightly marked, but induration is very manifest. This constitutes the plastic form.
Fig. 56.—Plastic form of infectious rheumatism (pseudo-anchylosis).
Exudative arthritis is the form usually seen at first. It may preserve its primary characteristics, but only too often proves to be the forerunner of the plastic form, which develops with the lapse of time. If nothing is done wasting becomes more marked, and is accompanied by cachexia. The animals are unable to rise, the complications inseparable from decubitus occur, and wasting or secondary purulent infection sets in.
Lesions. In the exudative form the changes are confined to inflammation and thickening of the synovial membranes, intra-articular exudation, and sometimes grooving of the cartilages without ulceration of the articular surfaces and without disorganisation of the joint.
The plastic form, on the other hand, leads to destruction of the cartilages, ligaments, and sub-cartilaginous bony layers, induration and calcification of the walls of the synovial cavity, and even periostitis of the ends of the bones, with the formation of false joints. The internal surface of the inflamed synovial membranes begins to granulate, the fibrous clots distending the articular dilatations are perforated by these extending granulations, and fibrous tracts soon develop even in the articulation itself, undergo calcification, and produce complete anchylosis.
Diagnosis. The diagnosis is easy. The animal’s history and symptoms, and the stationary character of the pain in the earlier stages are sufficient to prevent any error.
Prognosis. The prognosis is grave, but not fatal. In the exudative form recovery may follow early treatment. In the plastic form, however, the chances of success are extremely meagre.
Treatment. It is easier to prevent than cure, particularly in these forms of arthritis. The means are simple, and consist in always treating the post-partum infection as soon as it is recognised. The animals can be effectively safeguarded against later articular complications by the free use of intra-uterine antiseptic injections, until the uterine injuries have wholly healed, and by the administration of saline purgatives and diuretics.