Part 77

But whether the early spastic symptoms are well marked or not, paresis and even paralysis set in sooner or later. This usually begins as paraplegia, or exceptionally one limb only may be affected at first, causing the animal to walk on three legs. For a time the fore limbs may be free, and the patient attempts to move by dragging the hind limbs, which are extended backward. When the fore limbs become involved the animal remains down helpless and after awhile apathetic. Temperature and sensibility are both greatly lowered in the paralyzed limbs. Sometimes the spasms are lateral and the head may be drawn to one side.

In the animals that survive the early attack, there is likely to remain some lasting deformity, such as wry neck, arched back, stiff or swollen joints. Abscesses, which appeared in the inoculated rabbits after a lapse of four months, are a not uncommon sequel in sheep, the pus collecting in the neighborhood of a joint, or of the lymph glands of the axilla, inguinal region, breast or shoulder.

The succession of symptoms are in the main such as are observed in other cases of myelo-meningitis, first exalted function and later depressed and abolished.

Diagnosis. From other forms of myelo-meningitis it may be distinguished by its enzoötic occurrence on tick-infested pastures, which already have a reputation for causing this malady, by its appearance only in the season of the development of the tick, by the presence of the tick or of its sores on the skin, and by its entire absence from adjacent fields which are free from ticks. From paralytic rabies it is differentiated by the same conditions, and as a rule by the absence of rabies from the district and of any evidence of a bite. In tetanus the tonic persistent nature of the spasms, the absence of paralysis, the marked spasms of the muscles of the eye, and the usually isolated condition of the case should prevent any confusion. Braxy is to be distinguished by its emphysematous swellings near the surface of the body, and by the comparative absence of hyperæsthesia, spasm, or paralysis. The carcass in braxy undergoes much more rapid decomposition. Anthrax is more rapidly fatal, shows no such marked nervous disorder, has a dark, nonoxygenated and often incoagulable blood, an enlarged sanguineous spleen, and the characteristic anthrax bacilli. It attacks the larger herbivora as readily as the small.

Lesions. The most constant and striking lesions are found in the nerve centres. In many cases there have been found cerebral meningitis, involving the choroid plexus (Fair, Hamilton, Klein, Murray, McFadyean) with an encrease of the ventricular and subarachnoid fluid (Murray, Hamilton, Williams). The exudate may be yellow or rosy from contained blood globules (Klein). The meninges are thickened and the seat of ramified redness. In the region of the spine inflammation is found not only in the meninges but also in the cord, which may be blood-stained, softened (Mathewson, Goodwin, Robertson), or in older cases indurated (Robertson, Hamilton, Williams, Young). In this last condition there is a sclerotic condition of the neuroglia, and it may be a distinct atrophy. The exudate is usually abundant and more or less coagulated into a soft, diffluent jelly.

In many cases there is inflammation of the serous membranes of the chest (pleura, pericardium, endocardium), and even of the lungs (Fair, Hamilton, Klein). In some instances there has been inflammation of the stomach and intestines (McFadyean), liver and kidneys (Klein), and enlargement of the spleen has been noted. The most constant lesions appear to be those of the nerve centres, but the wide variety of organs involved in different cases sufficiently accounts for the variability of symptoms.

Prevention. As the ticks are the chief media of infection, the disease may be eradicated by their destruction. The burning of all withered grass and brush during the winter months will do much in this direction. Their destruction is rendered even more complete by ploughing and putting the land under a series of cultivated crops. By this means not only is the winter shelter of the tick removed, but the animal host which it requires for its complete development is denied it, and it must perish before the land is again seeded to grass. When the land is unsuited to cultivation, the same end may be in some measure secured by fencing off half the pasture, and leaving it unpastured for a season, meanwhile burning the dry grass or temporarily suppressing it by a liberal application of salt. The following year the pasture so treated may be restored to pasturage, and the other half subjected to the same course of treatment. In the absence of such thorough treatment, a liberal application of lime to a virgin soil will often bring a growth so fresh and appetizing that the stock keeps it closely cropped and thus removes the shelter for the offensive ticks. Finally, the ticks may be prevented from attacking the animals, by repeated use during April, May and June of a dip in which tar oil, cade oil, heavy petroleum or other odorous insecticide forms a component part (see the dip of Meek and Greig-Smith).

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.

Cowan strongly condemns heavy smearing with tar, which he believes to encrease the mortality, by lowering the general tone of the system: “Hoggs are very dull and listless for some time after being smeared with tar, more especially if heavily smeared; ... when the skin is taken off, every shed or opening in the wool where the tar has been laid on, is as distinctly visible upon the flesh as the stripes upon a piece of printed calico.”

It has been further alleged that the deaths are especially common during the full of the moon, the usual explanation being that the sheep are tempted to feed in the night and overload the stomach. It may be added that at such times the grass is taken in a cold—(often frosted) condition so as to chill the stomach and cause a congestive reaction, and that short of this, under the night dews the microbian ferments are moist and ready to start into full activity, while the herbage if it has been partly frosted is particularly susceptible to bacteridian attack.

Bacteriology of Braxy. The essential cause of braxy was revealed by Ivar Nielson in 1888, who demonstrated on the local lesions of the alimentary canal and the capillaries of various internal organs a bacillus which he named bacillus gastromycosis ovis. This is 2 to 6μ long by 1μ broad, occurring in pairs or filaments. The organism has an elliptical form and stains deeply at the extremities, while the central, bulging portion fails to take the color, is highly refrangent, and represents the spore. The non-spore-bearing bacilli are long, uniform rods with rounded ends. The germ is anærobic, grows readily in serum glycerine agar, and is gas producing and foul smelling. Liquefies gelatine. It is found abundantly in the congested parts of the abomasum and to a less extent in the bowels, in the mucosa, and in the submucous and subserous tissues. It was also found in the blood and in the small areas of degeneration in the liver and kidneys. Jensen obtained pure cultures through the survival of the spores when impure cultures were boiled for a few minutes.

Animals Susceptible. Inoculation of the cultures subcutem produces an affection resembling malignant œdema, or braxy, in sheep, Guinea pigs, mice, pigeons and hens, and less certainly in rabbits. Inoculation of a calf had no deleterious effect, while a second succumbed in forty-eight hours. In its pathogenesis this microbe appears to be more closely allied to that of malignant œdema than that of black quarter, as the latter attacks cattle very readily and has little effect on rabbits, pigeons and chickens.

Symptoms. The more obvious manifestations of braxy bear a resemblance to those of black quarter, so that the two affections have been often confounded. In both the attack is sudden, the course rapid and fatal, the back arched, the step short, especially with the hind limbs, and there are swellings which crepitate on pressure on the hind quarters or some other part of the body. Symptoms of colic soon appear, the sheep lying down and rising frequently and moving the hind limbs uneasily, and the abdomen becomes distended, tympanitic and tender. Rumination and feeding are promptly suspended, and as a rule defecation as well. Urine may be passed frequently in small amounts and of a high color. The pulse is rapid and often irregular and the breathing hurried and labored. In some cases the abdominal pain is less acute, the animal standing apart with drooping head, ears and eyelids and frothy lips, or lying by itself at a distance from the flock. Sooner or later emphysematous swellings appear on some part of the body, but most commonly on the hind quarter, which have a soft, doughy feeling and crackle or gurgle on pressure. In the great majority of cases, however, the disease runs a rapid course and ends in death in a few hours, and as the attacks are mostly in the cold of the night, the victim, which appeared well at night, is found dead in the morning. Cowan has often noticed that those that stepped short at night were dead next morning. In certain cases the sheep stood obstinately to the end and fell dead as if shot. When death was deferred for several days a common result was shedding of the wool.

Pathological Anatomy. A marked feature of braxy is the early putrefaction of the carcass. The rigor mortis quickly passes and the carcass bloats up and exhales a putrid odor. On removing the skin one sees extensive sero-sanguineous exudations, mixed with bubbles of gas of an offensive odor. The abdomen is tense and tympanitic and the anus protrudes. Visceral lesions are especially marked in the fourth stomach, the walls of which are thickened in patches or throughout by a hæmorrhagic or sero-hæmorrhagic exudation of a dark purplish color. If killed in the early stages this may be very restricted in area, but becomes general in animals that have died of the disease. Similar exudations are found on the walls of the first three stomachs, or on the small or large intestines. The fourth stomach and duodenum are, as a rule, empty of food, though containing a sanguineous liquid. The contents of the large intestines are usually dry and hard. Some serous exudate is usually present in the peritoneum, pleura and pericardium. The spleen may be normal or slightly enlarged. The liver is pale, soft and friable. The kidneys may be congested and swollen and usually show brownish areas of necrosis in which the bacillus is readily found. The blood is dark, and though it may be coagulated, the clot is usually soft and diffluent.

Prevention. Much may be done in the way of drainage and above all cultivation and liming of the braxy pastures, and again laying them down in grass. Cowan found that braxy diminished largely in ratio with the improvement and cultivation of the soil. A rotation of crops and the free æration of the soil tends to destroy an anærobic microbe or to render it non-virulent. Winter feeding is another well attested source of protection. Hay with turnips, oats, linseed cake or oil cake seems to encrease the tone and vigor, and to counteract the fermentations in the digestive organs which lay the system open to attack. Wholesome and nutritious food then must be a main stay whenever the health threatens to be undermined by insufficient or unwholesome pasture, by dried or withered grass, ferns or heather, by the watery grass of recent and rapid growth, by frosted and partially decayed herbage, or by pasture exhausted by overstocking or drought.

Fields and hills known to be infecting must be abandoned especially in late fall and winter and in the case of the younger and more susceptible sheep. Understocking is always better than overstocking as the flock is kept better nourished, stronger and with a greater measure of tolerance and resistance. Upon land covered with old, fibrous, astringent heather, burning is often of great value. The new growth of young heather is much more digestible and nutritious, and destitute of injurious astringency, and maintains a stronger and healthier flock.

Finally the question of immunization arises. Nielsen attempted this by drying and heating to sterilization the diseased kidney and injected small quantities of this suspended in water. Sheep treated in this way in Norway and Iceland have had a circumscribed inflammatory swelling and afterward appeared to resist casual infection when placed on the braxy fields. Jensen carried the experiment a step farther and inoculated his artificially immunized sheep with 2½ cc. of a virulent serum-gelatine-agar culture. It was rather unwell for half a day and walked lame but soon recovered. A dose of ¹⁄₃₀ cc. of the same culture killed in fifteen hours a larger sheep that had not been artificially immunized.

Treatment. Though some cases of braxy recover yet the treatment of the disease can hardly be seriously considered as yet. A disorder which is so rapid in its progress, so early associated with such great and rapidly extending lesions of the most vital organs, and which proves fatal so early and almost invariably, leaves little room for a successful treatment. In the milder cases, likely to recover of their own accord, this may be hastened by the internal use of antiseptics and purgatives, and perhaps even by antitoxic serum from the blood of an immunized animal.

SOUTH AFRICAN HORSE SICKNESS. ŒDEMA MYCOSIS. DUNPAARDZIEKTE. DIKKOPZIEKTE.