All the domesticated animals are subject to the annoyance which these worms occasion. They roll themselves into balls as large as a nut, and become entangled so much with each other that it is difficult to separate them. Sometimes they appear in the stomach, and in such large masses that it is almost impossible to remove them by the act of vomiting. It has been said that packets of ascarides have been collected in the stomach containing more than one hundred worms. These collections are rarely or never got entirely rid of. Enormous doses of medicine may be given, and the worms may not be seen again for several weeks; but, at length, they reappear as numerous as ever.
Young dogs are exceedingly subject to them, and are with great difficulty perfectly freed from their attacks.
species of worm is the
teres
. It would resemble the earth-worm in its appearance, were it not white instead of a red colour. They are very common among dogs, especially young dogs, in whom they are often attended by fits. Occasionally they crawl into the stomach, and there produce a great deal of irritation.
, and the most injurious of the intestinal worms, is the
tænia
, or 'tape-worm'. It is many inches in length, almost flat in the greater part of its extent, and its two extremities are nearly or quite equal. Tape-worms associate in groups like the others, but they are not so numerous; they chiefly frequent the small intestines. They are sometimes apt to coil themselves, and form a mechanical obstruction which is fatal to the dog.