This disease occurs in different parts of France, and has also been seen in Germany.
Causation. Lafosse in 1856 attributed it to the dark and dirty condition of the sheep-folds, a cause which certainly contributes to its propagation, though it is not the determining cause of the disease itself. The latter is a specific micrococcus discovered in 1875 by Rivolta, and thoroughly studied by Nocard in 1886 and 1887.
Symptoms. The course of the symptoms offers a certain analogy to that of septic engorgements and interstitial mammitis or mammary lymphangitis. As a rule only one gland is infected, but generally symptoms at once appear, indicating an extremely dangerous condition, viz., peracute mammitis. The patient suddenly becomes dull and entirely loses appetite, rumination ceases and respiration is short and jerky, although the bodily temperature does not always rise to any marked extent.
Local symptoms soon develop. The udder assumes a violet-red tint and becomes the seat of an erysipelatous swelling; the local temperature rises, but as the disease progresses it gradually falls again. Milk secretion ceases.
All these appearances rapidly become aggravated. The patient lies down; the œdematous swelling extends to the belly and even to the chest and thighs; the local temperature falls, indicating the imminence of gangrene; the teat becomes contracted, and the pulse is very frequent and almost imperceptible. From time to time the animal grinds its teeth.
The bodily temperature next falls to 98° or even 96° Fahr. (37° or 36° C.), and the animal shows extreme prostration. The subcutaneous swelling extends as far as the sternum in one direction and the quarters and perineum in the other. The udder crackles under the finger. Death occurs without a struggle.
All these symptoms follow as a rule in barely more than twenty-four hours. Nevertheless, in certain cases, the disease lasts for three, four or five days. Cases of spontaneous recovery are exceptional. The gangrenous part may become delimited and slough away, leaving an enormous suppurating wound, which slowly cicatrises. Even though the animals survive, they never recover condition, but remain weakly, so that, from a monetary standpoint, death would have been preferable. Moreover, the lambs are starved and require a foster-mother.
Lesions. Post-mortem examination reveals œdematous infiltration of the udder and surrounding connective tissue, and often extensive, diffuse gangrene. The serosity is of a reddish colour, and sections of the diseased udder of a violet tint. The tissues of the udder and the serous liquid contain the specific micrococcus.
It is very small, and stains readily by the Gram-Nicolle method. It grows rapidly in liquid and solid media, liquefies gelatine, and quickly renders neutral media alkaline.
The injection of a few drops of culture into the udder of a milch ewe reproduces the typical disease. In any other species it is without effect. Infection occurs through the open extremity of the teat, or the medium of a wound, and the microorganism is so virulent that it rapidly invades all the tissues.