Several kinds of worms infest the horse's intestines, but the most common is a long, white, round worm, tapering at each end. When a large number of this worm is present the horse loses condition, and has a harsh, rough skin, which clings closely to the ribs; the appetite is sometimes voracious, and not unfrequently the abdomen is distended.
There is another kind - a small thread-like worm, about an inch in length, which infests the rectum, near the tail, and causes intolerable itching: the horse is continually rubbing his tail and hind-quarters against anything with which he can come in contact.
For the larger worms, any tonic medicine, such as powdered gentian, sulphate of iron, sulphate of copper, etc., will generally suffice to weaken or kill them, when they may be removed by a dose of physic. It has been recommended to give the horse, in his food every day for a week, one-and-a-half drachm sulphate of iron and tartar emetic, and then administer a purgative, the diet meanwhile being bran and hay.
For the smaller worms, an enema of salt and water will very often suffice; or, after an ordinary enema has been given to clear out the intestine, another enema, composed of a quart of linseed-oil, in which six ounces of oil of turpentine have been mixed, should be administered. To prevent the invasion of worms, it is a good plan to allow a little salt in the food, or have a piece of rock salt always in the manger.