Part 105

Treatment.--If the worm can be reached it may be destroyed by cutting it in two with a pair of scissors, or it may be removed with forceps or with the fingers after wrapping a towel around the hand so that the worm can be held without slipping. Fumigation with tobacco or tar may cause the worm to release its hold if it can not be removed by other means. Ponds may be rid of infestation with bloodsuckers by the introduction of eels.

PARASITES OF THE STOMACH.

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 (H∆MONCHUS CONTORTUS).

The twisted stomach worm (HÊmonchus 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 1/2 inch to 1-1/4 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.

Cattle become infected with these parasites by grazing on pastures on which infested cattle, sheep, or goats have grazed and scattered their droppings. The worms in the stomach produce a multitude of eggs (fig. 14c) of microscopic size, which pass out of the body in the feces. In warm weather these eggs hatch in a few hours. If the temperature is below 40∞ F., they remain dormant, and if below freezing, they soon die. The eggs are also killed by dryness; moisture, on the other hand, favoring their development. The larvÊ which hatch from the eggs are microscopic in size, and, like the eggs, are, at first and until they have developed to a certain stage, very susceptible to freezing and drying. In very warm weather the larvÊ complete their development, so far as they are able to develop outside the body, in two or three days. In cooler weather the time required for this development is longer, and at temperatures below 70∞ F. 10 days to several weeks may be necessary. The larvÊ are then ready to be taken into the body. The eggs and early stages of the larvÊ apparently do not develop if swallowed, and only the completed larval stage seems to be infectious. In this stage the larvÊ migrate up grass stalks (fig. 15) or other objects, showing activity whenever the air is saturated with moisture; that is, during rains, fogs, and dews. When the air becomes dry and the moisture evaporates from the grass the young worms cease their activity, resuming their migrations when the air again becomes overladen with moisture. LarvÊ which have developed to the infectious stage, unlike the eggs and early larval stages, are able to survive long periods of freezing and dryness. In two weeks to a month after the embryos are swallowed they reach maturity and begin producing eggs.

Preventive treatment.--Preventive measures are important. As moisture favors the development of the embryos, high sloping ground is preferable for pastures. If low ground is used, it should be properly drained. The pasture should not be overstocked. Burning over the pasture will destroy most of the young worms on the grass and on the ground, and this means of disinfection under certain circumstances may be very advantageously used. The herd should be changed to fresh pasture as often as possible. Cattle should be supplied with water from wells, springs, or flowing streams, preferably in tanks or troughs raised above the ground. To a slight degree salt serves to protect cattle against infection with internal parasites, and plenty of it should therefore be kept accessible.

Affected animals should be isolated from the rest of the herd in hospital pens or pastures. A plentiful supply of nourishing feed is an important factor in enabling cattle to withstand the attacks of stomach worms and other intestinal parasites. The stabling of cattle, with the maintenance of clean and sanitary surroundings and liberal feeding, will often stop losses from internal parasites, even though no medicinal treatment is given.

Medicinal treatment.--In dosing animals for stomach worms it is advisable to treat not only the animals which are seriously affected, but the rest of the herd as well, since the parasites with which they are infested will remain as a source of reinfection to the others. The cattle should be removed to fresh pasture after treatment, if possible.

The animals to be treated should be deprived of feed for 12 to 16, or even 24, hours before they are dosed, and if the bluestone treatment is used should receive no water on the day they are dosed until several hours after dosing. In drenching, a long-necked bottle or a drenching tube may be used. In case the former is used the dose to be given may be first measured off, poured into the bottle, and the point marked on the outside with a file, so that subsequent doses may be measured in the bottle itself. A simple form of drenching tube (fig. 16) consists of a piece of rubber tubing about 3 feet long and one-half inch in diameter, with an ordinary tin funnel inserted in one end and a piece of brass or iron tubing 4 to 6 inches long, of suitable diameter, inserted in the other end. In use the metal tube is placed in the animal's mouth between the back teeth, and the dose is poured into the funnel, which is either held by an assistant or fastened to a post. The flow of liquid through the tube is controlled by pinching the rubber tubing near the point of union with the metal tube. It is important not to raise the animal's head too high on account of the danger of the dose entering the lungs. The nose should not be raised higher than the level of the eyes. The animal may be dosed either standing on all fours or lying on the side.

The position on all fours is preferred by some authorities, who believe that more of the remedy is likely to reach the fourth stomach when the animal is dosed standing than when dosed in other positions.

Great care should be used in dosing to prevent the entrance of the liquid into the lungs, and in the preparation and administration of the remedy to avoid getting the solution too strong or the dose too large.

Bluestone, or copper sulphate, has been extensively used in South Africa in the treatment of sheep and cattle for stomach worms and is recommended by the colonial veterinary surgeon of the Cape Colony as the best and safest remedy. To prepare the solution take 1 pound (avoirdupois) of pure bluestone, powder it fine, and dissolve in 9-1/2 gallons of warm water. It is better first to dissolve the bluestone in 2 or 3 quarts of boiling water, then add the remaining quantity of cold water, and mix thoroughly. This solution may be given to cattle in the following-sized doses:

Calves 3-1/2 to 4 fluid ounces. Yearlings 6 fluid ounces. Two-year-olds and over 12 to 16 fluid ounces.

In making up the solution only clear blue crystals of bluestone should be used. Bluestone with white patches or crusts should be rejected. It is especially important that the bluestone and water be accurately weighed and measured, and that the size of the dose be graduated according to the age of the animal.

The special value of medicated salts advertised under various trade names as preventives against worms is problematical. Commonly they contain little else than ordinary salt, the other substances being in such small quantity that their therapeutic effect is practically negligible. Definite evidence that they are more efficacious than plain salt is not yet available and their use is not recommended.

THE ENCYSTED STOMACH WORM (OSTERTAGIA OSTERTAGI).

This parasite is as thick as a fine hair and less than half an inch in length. It lives in small cysts in the wall of the fourth stomach (fig. 17) and is also found free in the cavity of the stomach. When numerous, these parasites cause a thickening of the stomach wall and disturb its digestive functions. The symptoms caused by this parasite are very similar to those produced by the twisted stomach worm. The life history of the encysted stomach worm is not known in detail, but it is undoubtedly very much the same as that of the twisted stomach worm. The same measures as recommended above for preventing infection with the twisted stomach worm should be used. Medicinal treatment would seem to be of little use, owing to the protected position in which the parasite occurs.

INTESTINAL PARASITES.

TAPEWORMS.

Two species of tapeworms (fig. 18) are known to occur in the small intestine of American cattle. They sometimes grow to a length of several yards and to a breadth of three-fourths of an inch. Small portions of tapeworms, consisting of one or more segments, are occasionally seen in the droppings of infested cattle. The life history is not known, but the infectious stage is undoubtedly taken in with the feed or water, infection being spread by the eggs of the parasite contained in the feces of infested animals. The eggs are perhaps swallowed by some small creature (an insect, worm, or snail) which acts as an intermediate host, and which when accidentally swallowed by a cow while grazing or drinking carries with it into her stomach the infectious stage of the tapeworm.

Adult cattle do not seem to suffer much from infestation with tapeworms, but in calves these parasites may cause scouring and emaciation.

Treatment.--Medicinal treatment for tapeworms in cattle is usually unsatisfactory, but the bluestone treatment used for stomach worms and mentioned above (p. 522) sometimes expels tapeworms. Arsenic in doses of 1-1/2 to 3 grains has been claimed to give good results in the treatment of calves for tapeworms. From results obtained at the Oklahoma Experiment Station in the treatment of tapeworms of sheep it would appear that the efficacy of the bluestone treatment against these parasites may be increased by the addition of tobacco. For use on cattle the bluestone and tobacco mixture may be prepared as follows: 13 ounces of snuff or powdered tobacco is soaked over night in about 8 gallons of water. To this decoction is added 1 pound of copper sulphate which has been dissolved in 2 or 3 quarts of boiling water. Sufficient water is then added to the mixture to make a total of 9-1/2 gallons. The doses of this solution are the same as for the simple copper sulphate solution, described on page 522, namely:

Calves 3-1/2 to 4 fluid ounces. Yearlings 6 fluid ounces. Two-year-olds and over 12 to 16 fluid ounces.

ROUNDWORMS.

A large roundworm (Ascaris vitulorum) measuring 6 to 12 inches in length, sometimes found in the intestines of cattle, especially calves, may cause inflammation and occasionally rupture of the intestine. Infection occurs through the swallowing of the eggs of the parasite in feed or water which has been contaminated with the feces of infested cattle.

A number of species of small roundworms, varying in size from an eighth of an inch to an inch or more in length, occur in the intestines. Of these may be mentioned the hookworm (Bunostomum phlebotomum) and the nodular worm (sophagostomum radiatum). The former is about an inch long and is found in the small intestine. The latter is somewhat smaller and is found in the cecum and large intestine. Hookworms, when numerous, may cause anemia and other symptoms similar to those caused by stomach worms (see p. 519). The injury to the mucous lining of the intestine from the bites of hookworms may cause severe inflammation, and affords an avenue of infection with the germs of various diseases. The adult nodular worms apparently do not attack the wall of the intestine, but derive their nourishment from the intestinal contents. Several species of small, very slender roundworms (Trichostrongylus), less than a quarter of an inch in length, sometimes occur in the small intestine and fourth stomach, and a severe gastroenteritis, or inflammation of the stomach and intestines, has been attributed to them. One species of small roundworm (Cooperia punctata) burrows in the wall of the small intestine and causes caseous nodules in the mucous lining. This parasite sometimes occurs in very large numbers in the intestines of cattle in certain sections of the country, and apparently does considerable damage.