Fig. 13.—Twisted stomach worms (Hæmonchus contortus). Outlines showing natural size of male (above) and female.
The stomach of cattle consists of four compartments, of which the first and fourth are most likely to be the seat of parasitic infestation. The first stomach, or paunch, contains large numbers of minute parasites known as protozoa, which are too small to be seen with the naked eye. These small organisms apparently are in no way injurious. A species of fluke (Paramphistomum cervi or a closely related species) is occasionally found in North American cattle, especially grass-fed cattle, attached to the inner surface of the first stomach (fig. 12). This worm is about one-half inch long, and somewhat conical in shape; hence the name, conical fluke, by which it is sometimes known. Although this parasite has been accused of producing serious effects, it is generally considered harmless.
Several species of roundworms may occur in the fourth stomach. Two of these are of special importance.
THE TWISTED STOMACH WORM (HÆMONCHUS CONTORTUS).
The twisted stomach worm (Hæmonchus contortus, figs. 13, 14, 15) is sometimes found in enormous numbers in the fourth stomach of cattle. Sheep, goats, and other ruminants may also be infested with it. Among the symptoms caused by this parasite may be mentioned anemia, loss of flesh, general weakness, dullness, capricious appetite, excessive thirst, and diarrhea. The anemic condition is seen in the paleness of the skin and mucous membranes of the mouth and eye, and in the watery swellings which often develop under the lower jaw ("poverty jaw"). If the fourth stomach of a dead animal is cut open and the contents carefully examined, the parasites, which are from ½ inch to 1¼ inches in length and about as thick as an ordinary pin, may be seen, if present in any considerable number, actively wriggling about like little snakes.
Fig. 14.—Twisted stomach worms (Hæmonchus contortus). Male (a), female (b), and egg (c). Enlarged.