Part 13

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.

PNEUMO-ENTERITIS IN SHEEP: HÆMORRHAGIC SEPTICÆMIA: SWINE PLAGUE.

Historic note. Microbiology: ovoid bacterium, motile, with polar stain, non-liquefying, chains, grows freely on culture media. Pathogenic to sheep, goats, dogs, hens, rodents, calf, ass. Views of Lignieres, Lienaux, and Conte. Symptoms: Acute form in young; hyperthermia, rapid pulse, troubled breathing, dulness, prostration, sopor, anorexia, congested petechiated mucosæ, offensive diarrhœa, emaciation, wheezing, cough, râles, crepitus, percussion flatness, abortion. Death in 6 hours to 3 days. Subacute form in mature: symptoms moderate, recoveries the rule. Lesions: fœtid carcass, blood staining of skin and organs, exudates, petechiæ, swollen congested lymph glands, peritoneal exudate, congested liver and spleen, gastro-enteritis, pleural effusion, lobular and peribronchial exudates, caseation, congested womb, placenta and brain, bacterium in lesions. Prevention: isolation, disinfection, secretions, manure, drainage, exclude tame and wild animals. Disinfectants.

Among the different forms of hæmorrhagic septicæmia in sheep, that observed by Galtier in 1889 in Basses Alpes, and later elsewhere in southern and western France and in Algiers, must be specially noted. It seems to be the same affection studied later by Lienaux, Conte, Besnoit and Cuillé and which prevailed from Tarn in the south of France, to Vendée in the west, and Somme in the north.

Microbiology. The pathogenic factor found in the lesions was an ovoid bacterium, a little larger than that of fowl cholera, motile, non-liquefying, with polar staining, and often showing in short chains of two or three joined end to end. It grows easily and abundantly in all common culture media, even on potato which fails to propagate the cocco-bacillus of Lignieres. This, with its ready transmission from swine to sheep and vice versa, apparently serves to differentiate it from the cocco-bacillus, and the disease from the hæmorrhagic septicæmia of Lignieres.

Pathogenesis. In Galtier’s first observations in Basses Alpes four separate flocks were infected by pigs brought all from one market, and placed in or by the pens of the sheep where they sickened and one in seven died in a few days. Then the mortality began among the sheep and ranged as follows: 1st flock lost 10 in 37: 2d flock 16 in 25: 3d flock 8 in 20: 4th flock 12 in 22. On one farm 10 sheep were sent to a neighbor’s just before the arrival of the sick pigs and escaped, and on another a second flock kept in outlying pens well apart from the home flock kept perfectly sound.

With cultures of the microbe in vitro, he successfully inoculated sheep, goats, dogs, chickens, Guinea pigs, rabbits, and, finally, a calf and an ass. The cultures were inoculated in different cases; intravenously, into the trachea, pleura, lung, and subcutaneous connective tissue, and one goat was infected by ingestion.

Lignieres claims that Galtier must have worked with a complex infection in which his (Lignieres’) cocco-bacillus was an essential constituent. The evidence of this is, however, lacking, and we must recognize that Galtier made cultures which showed the close relationship of his organisms to swine plague, and their lack of complete identity with those of the Lombriz.

Lienaux and Conte had pathogenic results in a limited number of animals only (rabbit, mouse, Guinea pig) illustrating the familiar truth of the variability in the pathogenesis of different specimens of septicæmic bacteria of the colon group.

Symptoms. 1. Acute Form. There is a sudden marked rise of temperature, often to 107° F., with acceleration of pulse and respiration. Sometimes death follows so early as to prevent the observation of other symptoms. If otherwise there supervene marked dulness, prostration, somnolence, anorexia, suspension of rumination, and more or less tympany of the rumen. The patient is found lying down, apart from the flock, indisposed to rise, with deep red, congested, arborescent conjunctiva and other mucous membranes, and petechial spots on these and on the white portions of the skin. The fæces, at first moderately firm and moulded in pellets, marked here and there with lines of mucus, or even blood, become on the second or third day soft, pultaceous, or watery and highly offensive. Parallel with this, emaciation advances with rapid strides. Breathing becomes more hurried, wheezing or snuffling, with a muco-serous, often bloody discharge from the nose, and an infrequent cough. Careful auscultation and percussion will often reveal the blowing or mucous râles, the crepitation or flatness on percussion of broncho-pneumonia. As the disease advances the petechiæ on skin and mucosæ extend, and extensive deep violet areas show especially on the inner sides of the arms and thighs, on the under surface of the tail, on the perineum and under the belly. Abortion is a common result, the lambs coming dead.

Death may occur in six hours, more commonly in two or three days, or even longer, the temperature going down to below normal in the last stages. In case of recovery, convalescence is slow, the animal remaining emaciated and weak, with lung lesions and persistent cough for a length of time. These poor imperfectly recovered animals continue to harbor the microbe and transmit it. Lesions of the liver and other organs, the result of this disease, are found in sheep that have survived the affection and are afterward killed for mutton.

Symptoms: 2. Subacute and Chronic Form. This is seen in mature sheep of two or three years, that have been infected when in the full vigor of life and health, during an open air life and by a limited dose of the virus. The temperature is less elevated, the circulatory and respiratory functions less disturbed, the dulness and prostration only moderate, the interruption of feeding and rumination transient and tympany slight. Cough and nasal discharge are however present and rather persistent, diarrhœa may be manifested, and marked emaciation occurs. There may be congestion of the mucosæ, but petechiæ and extensive bloody discoloration of the mucous membranes or skin are rarely seen. Abortion is not uncommon.

Recoveries are the rule in this type of the disease, though in some cases it will be delayed for weeks and may even then be imperfect.

Lesions. In the acute types of the disease decomposition advances rapidly after death, and the carcass from the first exhales a peculiarly heavy odor. The skin is discolored, the nasal mucosa is the seat of a muco-purulent or sanguinolent discharge, the anus is soiled with liquid fæces, the subcutaneous connective tissue marked by red arborescence and blood-stained areas, or by a gelatinoid exudation, the muscles at times deeply colored and petechiated, the lymph glands, especially the bronchial and mesenteric, are enlarged and congested of a deep red—the color being highest in the cortical zone. In some old standing cases these may have softened and acquired a grayish hue. They are rich in the specific bacterium.

The peritoneum is congested, petechiated, thickened, and more or less covered with thin false membranes, and it contains from a pint to three quarts of a sero-sanguinolent liquid which coagulates loosely on exposure. The liver is congested, with points of blood extravasation, and zones of degeneration (fibroid, fatty or necrotic), and sometimes abscess. The congestion extends to the spleen and pancreas. The abomasum and intestines are the seat of mucous gastro-enteritis. The mucous folds of the pyloric sac of the stomach are congested, reddened and petechiated, the small intestine has tracts and patches of congestion, thickening and softening, Peyers’ patches and the solitary glands are enlarged, and ulcers may be present on large or small intestines.

Effusion is usually found in the pleura, clear, grayish or bloody, with flocculi and false membranes, and further branching redness of the serosa. The mediastinum may be thickened by exudate especially around the glands, œsophagus and blood vessels. The lung shows lobular, interlobular and peribronchial exudates approaching at times to the appearances shown in lung plague, along with the atelectasis, emphysema and, in prolonged cases, caseation.

Less constant are congestions and petechiæ of the pericardium, heart, kidneys, vesical mucosa, testicles, ovaries or womb. The blood is dark and forms a loose coagulum. In case of abortion the umbilical cord is infiltrated and the placental membranes ecchymotic. The brain and spinal cord and their membranes are sometimes congested and infiltrated and a serous effusion exists in the arachnoid.

The bacterium is found more or less abundantly in each of the morbid lesions.

Prevention. Absolute seclusion of the sick and of all their products is the prime essential. The general distribution of the lesions throughout the body and the uniform presence of the bacterium in the lesions indicate that no part of the body and no secretion can be considered as free from infection. All parts of the body, all expectoration, saliva, fæces, urine, milk even must be withheld from all other animals, at least until they have been thoroughly cooked or disinfected. Manure must be burned, or buried deeply in quicklime. Contaminated pens, yards, wallows, streams and fields must be abandoned or thoroughly disinfected.

Galtier found that the virus remained active for six days in putrefying organic matter at 39° to 75° F.; in 25 days in water, at room temperature; the refuse litter, fodder, manure, and drainage matter from the infected place must be carefully guarded against. The virus steadily loses in force in such media, but remains infecting to animals injected with it. The most active disinfectants may be used on the pens and yards (copperas 5%, sulphuric acid 2% solution, or mercuric chloride .2%) while the contaminated fields should be abandoned for the season. All droppings may be treated with sulphuric acid (2%), creolin, lysol, phenic acid or copper sulphate. The susceptibility of practically all the animals of the farm, demands the exclusion of these, while that of rodents, renders necessary the further exclusion of wild mammals; and we may add birds, wild and tame, and if possible flies. The plowing of the contaminated soil will do much to obviate danger, yet the sheep folds and pastures should be separated by a considerable distance from any place where infected animals and objects have been. If drinking troughs for sound animals have been used by the sick or suspected they should be emptied and washed with a disinfectant (sulphuric acid 2:100).

ULCERATIVE (ERYSIPELATOID) INFECTION OF THE LIMBS IN CATTLE AND SHEEP.

New York outbreaks. Causes: wounds by sharp pebbles, streptococci, pure cultures, inoculations. Symptoms: swelling on lower limbs, abscesses, implicating tendons, bones, joints, and under hoof. Prevention: avoid septic or frosted mud, irritants, etc., disinfect surface, keep dry and clean, open abscesses, use disinfectants, separate infected.

This affection was seen in several herds in Oneida Co., N. Y., in the Spring of 1897. The geological formation of the region was a calcareous rock with a surface soil thickly impregnated with pebbles and small flat shaly masses. Sheep suffered in Western New York.