A very obvious precaution is to avoid the movement of sheep during April, May and June, from tick-infested pastures to others which furnish rank grass, brush or other suitable shelter for the preservation of the parasite.
It has been noticed that sheep indigenous to the tick-infested and louping-ill pastures are less susceptible than those that have been introduced from outside, but, as yet, no attempt appears to have been made to secure immunity by the use of sterilized products of the microbe, nor therapy by the resort to antitoxin. A liberal and tonic diet is an important element in prevention. Grain and hay should therefore be allowed whenever necessary to bring the sheep to early summer in good condition.
Treatment can hardly be said to have been attempted, though mild cases are allowed by the shepherds to recover. According to Meek, the deaths often average 10 to 20 per cent. of the flock.
BRAXY, BRADSOT, GASTRO-MYCOSIS OVIS.
Definition: Acute, infectious, bacteridian disease of sheep, with colic, enteritis, emphysematous swellings, dark, diffluent blood, and after death rapid putrefaction. Geographical distribution: Iceland, Norway, Faroe Islands, Scotland. Causes: inclement weather, exposed localities, low condition, winter food, chill, frosted grass. Bacteriology: Bacillus gastromycosis ovis: 2 to 6 μ by 1 μ, in pairs or filaments, sporogenous, polar staining, anærobic liquefying, gasogenic, found in the gastro-intestinal congested mucosa, serosa, liver, kidneys, blood. Pure cultures by boiling five minutes. Pathogenic to sheep, Guinea pig, mice, pigeons, hens and less certainly rabbits. Symptoms: resemble blackquarter, sudden, rapid, fatal, back arched, stiff hind parts, crepitating swellings on hind parts or elsewhere, colics, tympany, anorexia, pulse and breathing hurried, separation from flock, lying, drooping head, ears and eyelid. Usually found dead in morning when apparently well previous night. Lesions: early putrefaction, slight, transient rigor mortis, tympany, fœtor, sero-sanguineous exudates under skin, on fourth stomach and bowels, and elsewhere. Contents of large intestine dry, hard. Effusions in serosa. Spleen enlarged or not. Liver and kidneys congested, softened, small, pale necrotic areas containing bacillus. Prevention: drainage and cultivation, winter feeding, abandon infected pastures in late fall and winter as pasture for young, avoid overstocking, burn old fibrous heather. Immunization by sterilized kidney extract. Treatment.
Definition. An acute infectious disease of sheep, manifested by sudden attack, colicy pains, inflammatory and sero-hæmorrhagic lesions of the bowels, and sanguino-emphysematous swellings occurring subcutaneously and especially in the hind quarters. The blood is dark, tarry and comparatively incoagulable and after death putrefaction advances with extraordinary rapidity.
Geographical Distribution. Braxy is generally prevalent in Iceland where it was described over a century ago (1778) by Ketilson as “vinstrarfár” or “vinstrarplága” (“Omasum disease”). In Norway it prevails on the whole Atlantic border to as far north apparently as the sheep industry extends (Stavanger to Tromso Amt). The Faroe Islands are said to be affected throughout. In Scotland it prevails like louping-ill along the west coast especially, and embraces Caithness, Ross, Cromarty, Banff, Inverness, Aberdeen, Argyle, Bute, Ayrshire, Lanark, Galloway, Dumfries, Peebles, Selkirk and Roxburgh.
Causes. Like louping-ill this affection is associated with inclement seasons, exposed localities, and insufficient or indigestible food, but it differs in being an affection of autumn and winter rather than spring. It is rarely seen in summer. At a time when it was looked upon as an acute indigestion, its coincidence with hard frost or deep snow, was explained on the basis that the victim had been driven to eat dry, fibrous, indigestible grasses, brakens and heather. W. Williams who formerly identified the disease with anthrax, seemed to go back to this theory of indigestion. Though that is no longer tenable, yet it would be wrong to ignore the effect of inclement weather and unwholesome food in predisposing the animal system, and robbing it of the healthy tone which would otherwise have successfully resisted the infection in many cases. The occurrence of deaths after frosty mornings more than during mild weather, suggests at once the chill effected in the animal, the chilling of the paunch by the frosted grass eaten producing a subsequent congestive reaction, and the known facility with which frozen vegetables undergo rapid fermentation.
Cowan and Borthwick, (Transactions of Highland Society 1863) agree that the disease is especially prevalent when the land has been overstocked in summer, or when there has been a drought which withered up the pastures, and later a free growth of green herbage from the autumn rains. This they attribute to the “foul and unwholesome” character of the autumn growth, but it suggests no less the low condition of the sheep on the overstocked lands and the soft, aqueous character of the herbage grown rapidly in a comparatively cold season. Cowan quotes cases in which the lambs, weaned early and put in a separate pasture (hogg hirsel), suffered a mortality of 50 per cent., while in later years when allowed to remain with the ewes until winter, the deaths were reduced to 10 or 15 per cent. Here the more rugged health and vigor were manifestly strong prophylactic factors.
Both Cowan and Borthwick incriminate the withered heather and the dry, fibrous (“tathy”) and innutritious tufts of grass which make up a large proportion of many hill pastures in autumn and winter.