364 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



Cattle become infected with these parasites by grazing on pas- 

 tures on which infested cattle, sheep, or goats have grazed and scat- 

 tered their droppings. The worms in the stomach produce a mul- 

 titude of eggs 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, mois- 

 ture on the other hand favoring their development. The embryos 

 which hatch from the eggs are microscopic in size, and like the 

 eggs are susceptible to freezing and drying. In very warm weather 

 the embryos 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. ten days to several weeks may be necessary. The em- 

 bryos are then ready to be taken into the body. The eggs and early 

 stages of the embryos apparently do not develop if swallowed, hence 

 only this latter stage seems to be infectious. In this stage they mi- 

 grate up grass stalks 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 mi- 

 grations when the air again becomes overladen with moisture. 

 Embryos which have developed to the infectious stage, unlike the 

 eggs and earlier embryonic stages, are able to survive long periods 

 of freezing and dryness. In two weeks to a month after the em- 

 bryos are swallowed they reach maturity and begin producing eggs. 



Treatment for Twisted Stomach Worms. 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. Do not overlook pastures. 

 Burning over the pasture will destroy most of the young worms on 

 the grass and on the ground, and, if possible, this means of disin- 

 fection should be used at least once a year. Change the herd 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. 



Medicinal Treatment. Among the remedies used to remove 

 stomach worms may be mentioned coal-tar creosote, bluestone, and 

 gasoline. It is advisable to treat not only the animals which are 

 seriously affected, but the rest of the herd as well, since the para- 

 sites with which they are infested will remain as a source of rein- 

 fection to the others. The cattle should be removed to fresh pas- 

 ture after treatment, if possible. 



The animals to be treated should be deprived of feed for twelve 

 to sixteen or even twenty-four hours before they are dosed, and if 

 bluestone is used should receive no water on the day they are dosed, 

 either before or after dosing. In drenching, a long-necked bottle 

 or a drenching tube may be used. In case a bottle is used the dose 



