These tumors are after the type of muscle. They are sharply circumscribed and, as a rule, are very hard, a condition owing usually to combination with fibroma and are then known as fibromyoma. In fact, the clinical differentiation between myoma and fibroma is almost impossible. Myomas are found in the uterus, vagina, stomach, intestines, gullet, and bladder of a bovine animal. They grow very large, but, as a rule, are benign. Treatment should consist of their removal.
NEUROFIBROMA.
A true neuroma built up of nerve fibers and nerve cells is infrequent, if it ever occurs, in cattle. False neuromas, or neurofibromas, are knotty, spreading tumors of the size of a large potato, which are developed within the nerve sheaths and composed of nerve fibers and connective tissue bands interlaced. The commingling of these varied fibers is often so intricate that separation is practically impossible. This tumor is most frequently found upon the shoulder of cattle. Treatment is surgical.
ANGIOMA.
The angiomas are tumors composed mainly of blood vessels or blood spaces and are observed on the skin of man, where they are called "birthmarks" or "mother marks." Cavernous angiomas are seen in cattle, affecting the liver and the mucous membrane of the nasal septum. In the liver they appear as smooth, flat, nonprojecting tumors of a dark-red or purple color and of about the size of a silver 10-cent piece. They are somewhat softer in consistency than the adjoining liver substance into which they are gradually fused. These tumors are frequently observed by meat inspectors in livers of slaughtered cattle. Treatment of angioma is unnecessary.
ADENOMA.
The structure of this tumor is after the type of gland tissue. It is rarely seen in cattle except in combination with cancer or sarcoma. A growth which occurs more frequently in bovines, especially calves, and which in some instances bears a striking resemblance to an adenoma is the so-called goiter.
GOITER (STRUMA).
This is a noninflammatory enlargement or a hyperplasia of the thyroid gland. While it can not be definitely classed among tumors, yet, owing to its resemblance to the latter, it will be discussed at this time. The cause of goiter has never been definitely ascertained. Among the most probable causes may be mentioned heredity, insufficient and improper diet, close confinement, unhygienic surroundings, and an unknown toxic substance which is supposed to obtain in those localities rich in magnesium and lime salts. Certain organisms found in goiter have been suspected of producing this trouble, but their relation to the disease has not been satisfactorily proved. A goiter may consist of (1) simple enlargement of the follicles which are filled with albuminous matter (follicular goiter); (2) an increase of connective tissues between the follicles, causing the swelling to be dense and resistant (fibrous goiter); (3) a great increase in size of one or more follicles, forming a cyst (cystic goiter); (4) great dilatation of the blood vessels in the gland accompanied with pulsation with each heart beat (vascular goiter).