From careful study it seems quite certain that the Scottish “braxy” is identical with the Norwegian and Icelandic “bradsot”; it appears at the same season, and is intimately connected with climatic influences; it runs its course so rapidly that animals left healthy at night are found dead in the morning; and the pathological anatomy of braxy is the same as that of “bradsot.”
To Ivar Nielsen, of Bergen, must be ascribed the honour of elucidating the etiology of braxy. During the course of investigations, published in 1888, he found, partly in the local lesions of the intestinal track, partly in the capillaries of the internal organs, a special bacillus, easy to distinguish from that of anthrax, of which he gives the following description:
“The bacilli (B. gastromycocis-ovis) are oval, of a length varying from 2 to 6 micromillimètres, and a thickness of one micromillimètre. They are often in pairs, arranged in a straight line or meeting at an angle; in the former case, and especially if deeply stained, the pair may present the appearance of a single bacillus. Occasionally they form long chains. Near the centre of the bacillus, but not always centrally placed, may often be found a zone measuring more than half the total length of the bacillus, and exhibiting little or no colouration. It appears as though the stained portions gradually contracted, finally forming two deeply coloured masses at the poles of the lemon-shaped bacillus, which then somewhat resembles the bacillus of rabbit septicæmia, except that the unstained part of the braxy bacillus is larger and more rounded, appearing to be bulged out laterally. In dry preparations the bacillus is easily recognised on account of the highly refractile character of the colourless portion; but in sections careful search is often required, especially if the section be somewhat thick. Whether the colourless portion represents a spore cannot at present be said, though such appears probable. The bacillus is always found in the mucous membrane of the abomasum, and especially in the submucous and subserous connective tissue. In the other organs the bacillus may be present in considerable numbers, or, on the other hand, may be impossible to detect.”
The same bacillus has been found in the tissues of affected sheep both in Norway and in Iceland; the bacillus, when subcutaneously injected, produces a violent hæmorrhagic inflammation of the same character as one finds in the abomasum in cases of spontaneous braxy, and the local changes at the point of inoculation may, just as in spontaneous braxy, be accompanied by a general infection with degeneration of different organs, and with softening of the kidney substance.
The bacillus of braxy is anaërobic. In cultures it develops considerable quantities of gas, just as it does when inoculated into the tissues. It is closely related to the bacillus of symptomatic anthrax, which it somewhat resembles in general appearance, and of which it reminds one by its ability to produce hæmorrhagic inflammation in the muscular tissues. It is distinguished from the last named, however, by being pathogenic to swine, mice, pigeons, and poultry, which are not killed by the bacillus of symptomatic anthrax.
The bacilli of braxy, malignant œdema, symptomatic anthrax, together with Ivar Nielsen’s shortly described bacillus of whale’s septicæmia, and Thoma’s bacillus of malignant emphysema (found in extensive subcutaneous inflammation and emphysema in man), and certain others less well known, form a group of closely allied bacilli resembling one another in form, in being anaërobic, and in producing a sero-hæmorrhagic inflammation and emphysema, but differing in the manner of producing their effects.
Experience and analogy both seem to indicate that young animals occasionally suffer from mild attacks of braxy from which they recover. Such animals afterwards exhibit a well-marked immunity against the disease.
Ivar Nielsen attempted to vaccinate against braxy by a method resembling that used in black-quarter. He dried the diseased kidney tissue, and injected subcutaneously small quantities of the material thus obtained suspended in water. A slight local inflammation followed, which appeared to protect against later “spontaneous” infection. He has used this method in his own district, and states that it is also practised to some extent in Iceland. As far as one can judge—and of course a just opinion is very difficult to form—these inoculations appear of value.
The result of experiment, considered in conjunction with the good results of inoculation for black-quarter, would seem to indicate that Nielsen’s method of vaccination against braxy may yet prove of the greatest possible value, although the method will doubtless require modification in its details.
These modifications Jensen enumerates at some length.