Adult tapeworms of oxen are of relatively minor importance, but one tapeworm of sheep, viz., the fringed tapeworm (Thysanosoma actinioides), also known as Tænia fimbriata; Moniezia fimbriata deserves notice, as at times it forms a veritable scourge to the sheep industry of North America and South America.
Fig. 119.—Ventral and apex views of the head of the fringed tapeworm (Thysanosoma actinioides). × 17. (After Stiles, 1893.)
Fig. 120.—Segments of the fringed tapeworm (Thysanosoma actinioides), showing canals and nerves, and (f) fringed border, (t) testicles, and (ut) uterus. Enlarged. (After Stiles, 1893.)
Disease. The disease in sheep caused by the fringed tapeworm has been studied in detail by Curtice, who considers that next to scab it is the most important sheep disease of the western plains of North America. The financial loss it causes is extensive, and results from the failure of the lambs to fatten, the small crop of wool, and the weakening of the animals, so that they cannot withstand cold winter weather. The parasites develop slowly, and are present in considerable numbers before their presence is suspected. Toward September the lambs fail to grow as they should; in November the symptoms are marked. First, the worms produce local irritation of the intestine, which finally develops into a chronic catarrhal inflammation; their presence in the gall-ducts produces similar results, and obstructs the flow of bile; infected lambs are large-headed, under-sized, and hidebound; their gait is rheumatic, and they appear more erratic than the other sheep, standing oftener to stamp at the sheep dogs or herds, and lagging behind the flock when driven; the general symptoms are those of malnutrition, and Curtice considers them nearly identical with the symptoms of the “loco” disease; in fact, he states that it is extremely difficult to distinguish between the two diseases, and believes that the fact that the worms “may tend to produce depraved appetites and a morbid craze for a particular food is also reason for suspecting that the loco disease may depend on the tapeworm disease.” General systemic disturbances result from malnutrition; the usual fat is absent; serous effusions are noticed in the body cavities, serous infiltration in the connective tissue.
Treatment is similar to that of parasitic gastro-enteritis of sheep and lambs (which see).
CHAPTER IX.
DISEASES OF THE LIVER.
From the physiological standpoint the liver is an organ of such importance that its pathology should be studied as completely as possible. Furthermore, it is often the seat of a number of varying lesions, either of parasitic, toxic, infectious, or cancerous origin.
In animals of the bovine species the liver is placed in the right retrodiaphragmatic region, so that it is somewhat difficult to examine by any of the ordinary methods, like palpation and percussion. Under normal conditions it is entirely concealed beneath the hypochondrium, except towards the upper margin of the thirteenth rib, where it can be examined by palpation. When, as in various morbid conditions, it is considerably increased in size, it extends as far as the margin of the hypochondriac circle, thus becoming directly accessible to palpation and percussion. Sometimes it even enters the hypochondriac region, passing outside the omasum and abomasum, which it then thrusts towards the middle of the abdominal cavity.