This section is from the book "The Farmers Ready Reference Or Hand Book Of Diseases Of Horses And Cattle", by S. C. Orr. . Also available from Amazon: The Farmer's Ready Reference;.
Tuberculosis, or pulmonary consumption, is an infectious disease due to the bacillus tuberculosis which, through various channels, invades the animal's body. The most important consideration, with regard to animal tuberculosis, is the bearing that it has upon the health of the human family. That animal and human tuberculosis, or consumption, are identically the same has become an established fact; and it is also the belief of the most scientific investigators that animal, and especially bovine, tuberculosis is, to an enormous extent, responsible for the same disease in the human race.
The disease may be communicated from the animal to the human being in various ways. The milk of diseased animals is known to be one of the most prolific sources of communication. The flesh, though not always, has been known to contain the bacilli, and, as many people eat their meat "rare done," it thus becomes a source of danger. The discharge from the nostrils and from abscesses of diseased animals falling upon the ground or upon stable floors, becoming dry and being taken up as fine dust by the moving air, may be inhaled by other cattle and also by human beings. Milk, containing the bacilli, spilled upon floors of dwellings and dairy rooms, in this manner becomes a source of communication by inhalation, even to those who do not drink it.
A most serious aspect of this subject is the fact that this disease is not easily detected in its first stages; its progress is often slow at first, the animal being apparently in fair health for a year or two after the disease has begun its work. A case which came under my own observation was that of a cow belonging to Dr. S. D. Ross of Manhattan, Kansas The subject was a high-grade Jersey cow, kept to supply the family with milk. Some time during the spring of 1892 the writer was called in and found the cow slightly indisposed, as if from a cold. There was affected breathing, and a slight wheezing sound in the lungs. Tuberculosis was mentioned at the time, but as we had no microscope and did not then know the use of tuberculin, no test was made; and, as after a few doses of stimulants and tonics, the cow seemed to recover, nothing more was thought of the case until two years after, when your humble servant was again called to deliver a calf from the same cow. The cow was very thin in flesh, and Dr. Ross stated that she had not been doing well for a month or two. The calf was dead, but was soon delivered, and when the placenta was taken away its uterine surface was found thickly studded with nodules and small ulcers. Having access this time to a microscope, the writer prepared several specimens, in each of which were countless numbers of the bacilli of tuberculosis.
Symptoms. - The symptoms are often so slight at first as to be almost unnoticed, or may be mistaken for a common cold. The animal may be slightly off its feed for a few days; the muzzle may be dry, and, if a cow, there may be a decrease in the quantity of milk. Good nursing, with a few doses of medicine, soon checks the disease, and the animal is all right for a while. These attacks become more frequent and each one leaves the system in a worse condition until finally the symptoms never abate entirely. The hair will begin to look rough; the appetite will be capricious; the breathing will be affected; the animal cannot stand exertion; the ear placed against the side of the chest will detect a wheezing or whistling sound; there may be a cough and, as the disease progresses, there may be a discharge from the nostrils with a fetid odor; as the symptoms become more aggravated, there will be great emaciation; there will be complication with bowel troubles, and some times tubercular tumors or abscesses form about the head and neck and other parts of the body.
But, though these symptoms are sufficient to excite suspicion, the only true test is with the microscope, or by the hypodermic injection of tuberculin, both of which methods require experience. The disease is incurable, and as soon as its existence is proven, the affected animal should be destroyed and the carcass burned. The milk of tuberculous cows should not even be fed to pigs. The writer has seen several well-marked cases of the disease in swine.