hair-like worm from 0.4 to 1 inch (9 to 25 mm.) in length. In the adult
form it attaches itself to the mucous membrane of the fourth stomach or
abomasum, and lives by sucking blood. The blood present in the digestive
tract of the worm gives it a brown color, and the white oviducts which are
wound around the digestive canal cause the body to appear twisted. When the
twisted stomach worm is present in large numbers, the worms become mixed
with the contents of the stomach and can be readily found on making a
post-mortem examination.

_Symptoms of stomach worms_ are first manifest in the lambs (Fig. 76). It
is not until early summer that the disease appears in the flock. The
symptoms are not characteristic unless we consider an unthrifty, anaemic,
weak, emaciated condition accompanied by diarrhoea, during the summer
months characteristic of stomach-worm disease. The sick animals are unable
to keep up with the flock, and they like to stand about in the shade. They
move slowly, the back is arched, the appetite poor, the mucous membranes
and skin are pale and the hind parts soiled by the diarrhoeal discharge.
More acute symptoms than the above sometimes occur. The disease may last
from a few days to several weeks. A large percentage of the affected
animals die.

[Illustration: FIG. 76.--Lamb affected with stomach worm disease.]

The _treatment_ is largely preventive. Frequent changing of pastures and
dry lot feeding are common preventive measures. Permanent sheep pastures
lead to heavy losses from stomach worm disease. A very effective preventive
measure, as we may term it, is the practice of administering a vermifuge to
the ewes in the late summer and again in early winter. This may be given in
a drench, or with the feed. This prevents the reinfection of the pastures
every spring, and the young lambs are not exposed to this form of