SEPTICÆMIA HÆMORRHAGICA OF THE SHEEP: Lombriz.
Synonyms. Definition. Geographical distribution, Argentina, France, etc. Causes: bacillus; intravenously, etc., youth, verminous affections, low condition. Bacteriology: ovoid bacillus with polar stain, bleached by Gram’s solution, ærobic, nonmotile. Symptoms: Chronic form in summer, diarrhœa, arched back, stiffness, emaciation, flattened wool, segregation, impaired or depraved appetite, shedding wool, anæmic skin, dependent dropsies, sunken eyes, weak small pulse, temperature variable—elevated, nasal and buccal discharge, weakness, paresis, dulness, torpor, lung symptoms, arthritis. Diagnosis: from distomatosis and strongylosis. Acute form with high fever, constitutional disorder, colics, diarrhœa, death in 24 to 36 hours, subacute form. Lesions: black blood, congestions, and general petechiæ. Lungs, liver, kidneys and spleen, congested, swollen. Subacute cases have lighter blood, and lesions. Chronic cases anæmic, blood diffluent, lymph glands enlarged, congested; connective tissues and serous cavities dropsical, gastric, intestinal and hepatic worms, spleen shrunken. Mortality: great in acute, less in chronic. Prevention: segregation, exclusion of all sheep from unknown or suspected flocks, antiseptic dip and quarantine for new purchases, expose a few as a test; cleanliness, disinfectants, avoid watershed from infected lands, wide range, outdoor life, generous diet, remove weak, emaciated, anæmic. Immunization. Treatment.
Synonyms. Pasteurellosis Ovina. Infectious Pneumo-Enteritis.
Definition. An infectious febrile affection of the sheep, chronic or acute, characterized by dulness, stiffness, or paresis, anorexia, thirst, disorder of the breathing and digestive organs, black diffluent blood, petechiæ, reddish effusions in the serosæ or connective tissue, and congestive or inflammatory lesions of the lungs, liver, kidneys and intestines. The presence of a cocco-bacillus (diplococcus, strepto-cocco-bacillus, pasteurellosa) in the lesions is especially characteristic.
Geographical Distribution. Though Lignieres first demonstrated this as a bacteridian disease in the Argentine Republic, he was, after his return, able to identify the same affection in the flocks of almost every department of France, in newly imported English Lincolns and German Merinos, so that there can be little doubt that the malady exists in all or nearly all countries engaged in sheep husbandry, though it has been usually attributed to parasitisms of the lungs, liver or alimentary canal alone.
Causes. The essential cause is manifestly the bacillus, which Lignieres has isolated, cultivated in vitro, and successfully inoculated intravenously in the sheep, which he also infected by feeding the pure cultures. Intravenously it proved fatal to Guinea pig, rabbit, pigeon, chicken, rat, mouse, horse, ass and ox. Yet many other accessory causes must be admitted as operating in different cases.
Youth shows the greatest susceptibility whether the victim be mammal or bird. So marked is this influence that the principle sufferers are lambs just weaned or yearlings. Yet mature animals, that are debilitated from any cause, also fall victims. The measure of immunity usually noticed in mature sheep may well be attributed to a previous mild and non-fatal attack of the bacillus.
Verminous affections are undoubtedly predisposing causes, hence, the common practice of attributing the malady to the worms alone. This again in part explains the susceptibility of the young which so often harbor worms to a dangerous extent. It seems to matter less what worms are present than, that they are in sufficient numbers to greatly deteriorate the health. It is noticeable, however, that those worms that make breaches in the mucosæ, have been noted as infesting the victims of this malady. In the stomach worms sent from Argentina, Railliet identified Strongylus Contortus, S. circumcentus, and S. instabilis and in the duodenum S. filicollis and S. Curticei. These, like the distomata often found in the liver, are blood suckers and not only render the animal anæmic, but make numerous perforations to act as infection-atria. The various lung worms, encysting themselves in the air sacs and determining local congestions may act in the same way, opening channels for the entrance of the microbe.
Low condition or a low tone of health from any cause predisposes. Old, worn out animals, ewes in lamb, or those just lambed, sheep that have been shut up and denied proper exercise in winter, those on poor feeding and perhaps nursing twins, those that have suffered from any debilitating disease of any kind are especially obnoxious to a dangerous attack.
Microbiology. The microbe, which Lignieres found in the pulmonary lesions, is one of the colon group of pathogenic bacteria that have been classed together as pasteurella. It usually appears as a very minute ovoid bacillus which stains promptly and deeply at the poles in fuchsine or gentian violet, leaving a clear median part, so that it seems a diplococcus. It bleaches readily in Gram’s solution. Its form varies in different culture media sometimes showing long bacilli, and sometimes streptococco-bacilli, but the usual and characteristic appearance is that of a cocco-bacillus, and to this it constantly returns. The microbe is ærobic and nonmotile (the slow zig-zag motion sometimes seen does not seem to be automatic). In peptonised bouillon it produces opacity in 18 hours, or in simple bouillon in 24 to 48 hours, the best temperature being 100° F. Gelatine plate cultures are slow because of the compulsory low temperature, yet in 36 to 48 hours it forms pale blue, translucent, round colonies the size of a pin head. It never liquefies. In coagulated blood serum it forms only a thin transparent pellicle hardly visible, and there is no growth on potato.
Symptoms: Chronic Form. In Argentina, Lignieres observed the disease especially during the hot summer months (December to May), and after weaning in the lambs. This may be from the marked change of food, from the greater activity of microbian life at this season, from the exhausting effect of the heat, or from a combination of two or more of these conditions. It appears alike in the sheepfold, and on the open prairie. In considerable flocks the symptoms may be at first overlooked, so that the death of several sheep may be the first thing to draw attention. Then a certain number are found to scour, arch the back, walk stiffly, lose condition, and have the wool flattened and devoid of yolk (clapped wool). The sheep may be dull, lagging behind its fellows, or lying apart by itself, ruminating infrequently and for shorter periods than natural, and there may be inappetence, or depraved appetite (eating earth), though some eat well to the end. Irregular and at intervals capricious appetite is a frequent condition. When caught and examined, the wool is easily torn out, the muscles are soft and wasted, (the leg muscles may have practically disappeared), the bones stand out at all points, the skin is pale, thin, bloodless and devoid of its subcutaneous fat, (paper skin), there may be œdemas along the ventral aspect of the body, pitting on pressure, and between the branches of the lower jaw (poked), the eyes are sunken, the conjunctiva may be puffy and œdematous, but like the muzzle and mouth they are pale and anæmic and the pulse is small, though the excitement may have roused cardiac palpitations. The temperature varies from time to time often reaching 105° or 106° F. There is liable to be a muco-purulent discharge from nose and mouth especially noticeable during drinking. As the disease advances the subject becomes weak, paretic, dull and stupid, it remains down without interest enough to seek food, though still eating if it is brought to it. The head is usually rested on the flank, and the animal often lies so for days in a state of semi-stupor without disposition or ability to rise, paretic or paraplegic. Auscultation may sometimes detect a mucous râle or crepitus, and percussion a flatness of sound over some part of the lung. Chronic arthritis is an occasional symptom.
Diagnosis. The symptoms closely resemble those of distomatosis or strongylosis, and the disease is often complicated with one or more of these, so that it may become difficult to judge how much is due to the microbian infection and how much to the helminthiasis. The presence, continuously or intermittently, of the hyperthermia is almost pathognomonic of the operation of the microbe.
Acute Form. This has been particularly observed in the ewe just after lambing, when the system is especially susceptible to microbian invasion, and little able to cope with it. There are hot ears, nose and feet, temperature of 104° to 106° F., accelerated pulse and breathing, anorexia, ardent thirst, deeply congested mucosæ, colicy pains, pawing the ground, frothy or bloody diarrhœa, arched back, pendent head, ears and eyelids, muscular trembling, albuminous urine, plaintive cries, dark red vaginal discharge, muco-purulent or glairy nasal discharge, and death in 24 to 36 hours. Such animals may be in fair condition or even fat, no time having been allowed for emaciation.
In other cases death may be delayed for three or four weeks, with the same general symptoms, only less marked. In such cases, pregnant ewes are likely to abort, and the lambs are born dead, or prove weak and listless, and die when a few days old. Some have too little energy to suck; others suck heartily but perish all the same on the second or third day, after diarrhœa, thirst, hyperthermia, prostration, and stupor.
Lesions. These vary according to the type. In the rapidly fatal cases there is dark colored blood, with congestion of the serous and mucous membranes, which, together with the skin and often the solid tissues, are covered with petechiæ, and even circumscribed hæmorrhages. The lungs, liver, kidneys, spleen, and many of the lymph glands are congested and swollen, seeming at times of a black hue as if blood-saturated. The lesions, indeed, indicate an acute septicæmia.
In cases that have survived three or four weeks, the morbid changes are slighter, the blood is brighter in tint, and the congestions less deep in color, ecchymoses may be especially confined to the heart, abomasum and small intestines, which may also show hæmorrhages. Enlargement and congestion of the lymph glands are the rule, while pulmonary consolidation and gastro-intestinal mucous inflammations are frequently found. As in the more acute types the urine is albuminous.
In chronic cases the anæmia is prominent. The clot is soft, relatively small, elastic and black, the serum is relatively very abundant and pale. The red globules are greatly reduced in numbers, and there are a number of giant cells which stain deeply as in chlorosis. The lymph glands are usually enlarged, softened and slightly congested but rarely the seat of blood extravasation. The tissues generally are pallid, soft and shrunken. There is a marked absence of subcutaneous and intermuscular fat, while the connective tissue is more or less infiltrated with a transparent, watery lymph. The serous cavities usually contain more than the normal amount of fluid, transparent or straw-colored, and with few globules or granules. Congestions and even shreds of false membrane are sometimes present on the serosa. In some cases the lungs and bronchia are the seat of inflammatory exudates, causing nodular consolidations of from one-half to one inch in diameter. Not unfrequently the lungs show strongylosis as the fourth stomach shows strongylus contortus, the small intestines strongylus filicollis, tæniae (expansa, fimbriata, etc.), the large intestines æsophagostoma Columbiana, and tricocephalus affinis, and the gall ducts distoma hepaticum and distoma lanceolatum. In these chronic cases the spleen is usually shrunken, and the liver firm, sometimes even cirrhotic.
Mortality. The acute cases are usually fatal. Those that assume a chronic form, if free from local lesions in important organs, well-fed, and, above all, kept in the open air, and changed to a different pasture, tend largely to recovery.
Prevention. The propagation of the infection from animal to animal is slow and somewhat uncertain, and when introduced by the purchase of a new ram or other animal, it may take a considerable time to affect the stock extensively, but for this reason, and because an apparently sound sheep may harbor the germ, it is difficult to oppose it successfully by segregation. All the same, it is desirable to take all possible precautions against its advent, and among these, the exclusion of strange sheep from noninfected pastures and flocks. When the time comes to make an outcross from the home strain, the ram must be selected not only for his pedigree and individual qualities, but no less for the soundness of the flock from which he is taken. If the lambs of that flock have been decimated by disease, the best blue blood, and most faultless form should not tempt the flockmaster. He should be rejected in favor of one taken from a flock that is above suspicion. It matters little if it can be plausibly argued that the mortality came from worms of the lungs, liver, or digestive organs; these in themselves may soon ruin any flock, but they, too, often coexist with the microbe of infectious septicæmia, and, when this is the case, they prepare the system and open a way for its invasion.
New purchases should not only be selected from apparently sound and guaranteed stock, but they should be passed through an antiseptic dip on arrival, and then if possible quarantined in a special enclosure until they shall have proved their freedom from infection. A valuable ram may be placed with some lambs or yearlings in close quarters to ascertain whether he has brought the infecting matter with him. If all escape after some months the presumption is that he is sound. Perfect cleanliness of the fold should be maintained, and disinfectants may be freely used in it.
The water supplies should be watched, rejecting streams that have drained sheep-pastures where there have been marked losses of lambs and ewes. Water from deep wells without any surface leakage is to be preferred.
When new stock (ram, ewes, lambs) are of necessity mixed with the sound herd, a wide range, an open air life, and abundant dietary must be secured. The system that is full of strength and vigor can better resist the microbe and even throw it off entirely, whereas the weak, confined subject succumbs. For the same reason, the weak, emaciated and debilitated subjects should be at once separated from the sound flock, and kept in a special enclosure, in the open air, on a rich diet. Should they harbor worms, this seclusion is even more imperative. (See parasites of lungs, liver, stomach and bowels).
Lignieres advocates immunization by serum prepared on the Pasteur method, but, as he has not divulged the exact technique of its preparation, it is impossible as yet, to give this an unqualified endorsement. It has this in its favor that the mature sheep, in full vigor of middle life, though in an infected area, usually resist the infection, while the young, old, debilitated and verminous suffer. Opposed to it are these considerations that are recognized by Lignieres himself;—1st, The acquired immunity is not perfect, as shown by occasional relapses in sheep that have survived a first attack; 2d, The serum inoculation is not only useless, but dangerous in animals that already harbor the germ; I may, add 3d, Any acquired parasitism or debilitating disease may tend to break down the immunity and prostrate the system under the infection. Lignieres advises that the serum treatment should be restricted to the new born lambs in infected herds, or herds in infected areas. The first three or four weeks after birth are to be preferred for the operation, though failing this it may still be ventured on, up to a few days before weaning. The longer it is delayed the greater the danger of a preëxisting infection, and of untoward results from the new access of infecting material, on the back of an infection which varies so extremely in its pathogenic potency. Even among the new born lambs, Lignieres would restrict the serum therapy to the strong, robust and healthy, and, if they survive the resulting fever, would repeat the treatment after the hyperthermia has ceased. No satisfactory treatment of the disease has been made. An open air life, a generous diet, and a course of iron, and bitters will, however, be of use in serving to improve health, digestion and vigor, to solicit a better production of red globules, and to enable the patient to survive the period of anæmia, prostration and debility. Antiseptics like quinia, the sulphites and the iodides might be used as adjuncts.