Soil is the prime factor in preserving and propagating the microbe, when it is naturally wet, impermeable, and rich in decomposing animal and vegetable matter. The microbe of anthrax may enter the body by several channels. It may be taken in with the food or drink. It may be breathed into the lungs. It may enter through abraded surfaces on the skin. It may be inoculated into the body by biting insects.
There are several forms of the disease and these are determined by the modes of entrance of the virus. One form, which occurs especially in sheep and cattle, at the commencement of an outbreak, and which is characterized by the suddenness of its onset and its high degree of fatality, is known as the apoplectic, or fulminant form. Without showing any previous symptoms, an animal will suddenly be seized with loss of appetite, trembling, uneasiness, irregularity of movements, difficult breathing, blueness of the nostrils, bellowing, convulsions and hemorrhages from the natural openings. Death may occur in a few minutes or in four or five hours.
Another type is known as anthrax fever, or internal anthrax. Here we have distinct symptoms, the most important being high fever of from three to four degrees, excitability and restlessness. Blood may ooze in drops from the nose, eyes, or ears, and from inside of the forearm or thigh, in sheep. There will be trembling, prostration, numbness of the loins, thirst, grinding of the teeth, colicky pains, bloating, bloody discharges, palpitation of the heart, difficult breathing, blueness of the visible mucous membranes, jerking of the muscles of the back and neck, and rolling of the eyes. The animal will die in comatose state, or in convulsions, and death will occur in sheep in about a day. Cattle will live from two to five days, and horses from one to six days.
A third form is external anthrax, which manifests itself in swelling of the tongue, throat, rectum, and skin in cattle; and of the tongue, throat, neck, shoulders, withers, flank, or thigh in horses. These swellings have a firm, doughy feeling, are not painful generally, and show a marked tendency to gangrene. They never suppurate. If cut (this should never be done), they discharge a pale, straw-colored liquid. In this may be found the microbe.