Treatment.—There is no specific treatment for this affection. Copious blood letting in the earliest stages has been highly recommended, however, as this has a tendency to deplete the system and lessen the exudation of inflammatory products. Antiseptic washes, such as 4 per cent boric-acid solution to the eyes and Dobell's solution applied to the nose and mouth with ice poultices over the crest of the head and frontal region, have also proved efficacious. Calomel should also be given in 1-dram doses twice a day for three days, and in severe cases, involving the respiratory tract, a powder containing ferrous sulphate, quinin, and subnitrate of bismuth, given twice a day, will be found beneficial. At the same time it must be remembered that much greater success is to be looked for in the preventive treatment. This consists in the removal of the healthy from the infected animals (not vice versa) and thorough cleaning and disinfecting of the contaminated stables. If the floors are low and damp, they should be raised and made dry. If this can not be done, place a layer of cement under the stable floor to prevent water from entering from below. The stable should be well ventilated and the soil in the pastures thoroughly drained. If this is carefully carried out, the contagion should be destroyed and the danger of the reappearance of the disease in a great measure lessened.
MALIGNANT EDEMA.
Malignant edema, also termed gangrenous septicemia, is an acute, inflammatory disease of domestic and wild animals, resulting from the introduction of a specific organism into the deep connective tissues of a susceptible animal and proving fatal in many instances within 24 to 48 hours. The disease may be inoculated from one animal to another, but only by inserting the virus deeply below the skin. It is infrequently met with in cattle, but may follow operating wounds, as roweling, castration, and phlebotomy, which have become infected with septic matter, soil, or unclean instruments. In the pathological laboratory of the Bureau of Animal Industry the organism has also been obtained from the infected muscles of a calf that was supposed to have died of blackleg, and, as a result, all blackleg virus is thoroughly tested before it is made into blackleg vaccine in order to exclude the malignant-edema organism. The essential cause of malignant edema is a long, slender, motile, spore-bearing bacillus, resembling the bacillus of blackleg, and which can develop only in the absence of the atmosphere. Unlike the bacilli of anthrax and blackleg, which are confined to certain districts, this organism is widely distributed and found in ordinary garden soil, foul water, and in the normal intestinal tract of the herbivora. It may be brought to the surface of the soil by growing plants, rains, winds, or burrowing insects and rodents. In animals that have succumbed to the disease the germ is confined to the seat of infection, but a few hours after death it may migrate through the blood channels to other parts of the body. The bacillus may attack man, horses, asses, goats, sheep, pigs, cats, dogs, and poultry. Adult cattle, although refractory to experimental inoculation, suffer from natural infection, while calves are susceptible to both these methods of exposure. (Kitt.) The introduction of the bacillus into abrasions of the skin and superficial sores rarely does any harm, because the germ is quickly destroyed by contact with air. If, however, the organisms are inserted deeply into the subcutaneous tissues of susceptible animals, they quickly develop, producing a soluble poison, which is the fatal agent.
In lamb-shearing season, or after docking or castration, the mortality is higher among these animals because of wounds inflicted at such times. The application of antiseptics to wounds thus made will reduce the percentage of deaths to a minimum.
Symptoms.—Usually the first symptoms are overlooked. In the early stages the animal appears listless, disinclined to move about, and lies down in shady and quiet places. If forced to move about, the hind legs are drawn forward with a peculiar, stiff, dragging movement, and there may be slight muscular trembling over all the body, which becomes more intense as the disease progresses. When driven, the animal shows signs of fatigue, ultimately dropping to the ground completely exhausted. Breathing becomes fast and painful, with frequent spasmodic jerks.
The pulse is quick and weak and the temperature is 106° to 107° F. An edematous, doughy, and painful swelling appears at the point of infection. This tumefaction spreads more and more, and crackles on pressure. In case of an open wound, a fetid liquid and frothy discharge is observed. The center of the swelling may appear soft and jellylike, while the margin is tense, hot, and painful. The symptoms increase rapidly, resulting in coma and death.
Lesions.—After death the fat and subcutaneous tissues surrounding the infected area are infiltrated with a yellow gelatinous material containing an orange-colored foam, due to the presence of gas bubbles.
The muscles at this point are friable, spongy, and of a uniform brownish tint, dissociated by gas and with a blood-tinged exudate. This gangrenous tissue, when present before death, can be removed without pain to the animal. The intestines are generally normal, but, together with the peritoneum, they may be inflamed, and the lungs are usually the seat of an edema. The spleen, liver, and kidneys retain their normal appearance, in marked contrast with anthrax.
Differential diagnosis.—Unlike blackleg, this disease never appears as an epizootic but in isolated cases. It may also be differentiated from the former by the history of a recent parturition or surgical operation, by the presence of an external injury at the site of the swelling accompanied with a fetid liquid discharge, and the gangrenous appearance of the tumefaction. Man is susceptible to malignant edema, but not to blackleg. Malignant edema may also be easily differentiated from anthrax in that the blood and spleen are normal in appearance, while in the latter disease the blood is dark and of a tarlike consistency, and the spleen appears swollen, injected, and softened. The local tumor in malignant edema contains gas bubbles, which are absent in anthrax swellings. Inoculation experiments of guinea pigs, rabbits, and chickens will also disclose the differences among the above-mentioned three diseases, since all these species are killed by the germ of malignant edema, only the first two species by the anthrax bacillus, while the guinea pig alone will succumb to the blackleg infection.
Treatment.—Treatment is chiefly surgical and consists in laying the infected areas wide open by free incision, followed by a liberal application of a 30 per cent solution of hydrogen dioxid and subsequently a 5 per cent solution of carbolic acid. Usually the disease when observed has advanced to such an extent that medicinal interference is without avail. Preventive treatment is by far the most desirable, and consists, essentially, in a thorough disinfection of all accidental and surgical wounds, the cleansing of the skin, and the exclusion of soil, filth, and bacteria during surgical operations of any nature. Sheds, barns, and stables should receive a thorough application of quicklime or crude carbolic acid wash after all rubbish has been removed and burned. All dead animals should be burned or deeply buried and covered well with quicklime.