The streptococcus causing this mammitis colours readily with thionin and methylene blue. It can be cultivated in liquid and solid media containing sugar or glycerine, but growth is impeded by the presence of peptone or common salt. Under ordinary circumstances the culture dies after some weeks, but if the acidity of the medium is neutralised by the addition of powdered carbonate of lime, it preserves its vitality for six or eight months. The culture when injected into the udder of a healthy cow or she-goat reproduces the disease. The microorganism is not pathogenic for any of the smaller animals used for purposes of experiment.
Diagnosis and prognosis. The diagnosis is easy, the presence of the sclerotic nodules being characteristic, whilst in doubtful cases a microscopical examination can always be made.
The treatment should be prophylactic and curative.
Prophylactic treatment comprises disinfection of the milkers’ hands, which are the ordinary vehicles of contagion, and disinfection of the cow’s udder. Diseased animals in a byre should be milked last of all, and the milk should be destroyed.
Curative treatment is confined to local antiseptic injections. Warm concentrated boric solution gives good results. The injections may be repeated three or four times a day after milking, the liquid being left for a certain time within the udder. In this way animals suffering only from a slight attack may be cured, but when the disease is already somewhat advanced injections lose their effect.
Injections of fluoride of sodium (·1 to ·5 per cent. strength) appear to be much more effectual. Moussu claims to have cured by this means several old-standing cases where all four quarters of the gland were diseased.
These injections necessitate the same precautions as those above indicated for securing perfect asepsis. In grave cases it is very difficult to prevent the disease from extending in infected stables, because the necessary precautions cannot be observed.
CHRONIC MAMMITIS.
Chronic inflammation of the udder may form a termination of ordinary acute mammitis, or it may result from infection with organisms of a less virulent type.
In cases of acute mammitis, where severe injury of the interstitial tissue or mammary parenchyma has occurred, its physiological function is partially destroyed. The circulation is disturbed, the vessels undergo change, the layers of connective tissue are indurated and sclerotic, the epithelial tissue is not fully restored, and chronic inflammation of the udder persists.