18 



Circular 338, U. S. Department of Agriculture 



the walls of the digestive tract, get into blood vessels or lymph vessels, 

 and finally many of them get to the lungs, usually by wa}^ of the blood 

 stream through the liver and heart. In the limgs they leave the blood 

 and enter the air passages, ascend these air passages to the mouth 

 and are swallowed. On reaching the intestine they settle down and 

 grow to mature worms, the females beginning egg production in the 

 course of a few weeks. Prenatal infection of the pups in the uterus 

 of the preg-nant bitch has been shown to occur with the second of 

 the ascarids referred to above. 



Symptoms. — These ascarids are especially injurious to pups, and 

 as many as 2,000 have been found in one animal. They cause de- 

 rangements of the appetite and digestion, and heavily infested pups 

 become unthrifty and emaciated and may die if the condition is not 

 relieved, "^^^len present in large numbers the worms may form 

 masses which produce a stoppage of the bowels, they may wander 

 into the ducts of the liver, into the stomach, causing the animal to 

 vomit the worms, or may crawl up the esophagus and enter the 



lungs or nostrils. The yoimg 

 worms leaving the blood and 

 entering the air passages of 

 the lungs may cause such 

 serious injury to the lungs as 

 to produce pneumonia and 

 this may terminate in death. 

 The presence of these worms 

 may be suspected when pups 

 are unthrifty and have a his- 

 tory of passing worms or 

 when they are known to have 

 been associated with older 

 dogs infested with worms. 

 Diagnosis is best made by a 

 e, Toxasca- microscopic examination of 

 the feces and the finding of 

 the eggs (fig. 16). This ex- 

 amination can be made by any competent veterinarian. 



Treatment. — The most effective drug for removing ascarids from 

 dogs is oil of American wormseed (chenopodium). It may be 

 given in hard or soft gelatine capsules at a dose rate of one-fourth 

 fluid dram (1 cubic centimeter) for a dog weighing 22 pounds (10 

 kilograms). This should be immediately preceded or followed by 

 1 fluid ounce of castor oil. The dog may vomit after treatment, 

 but experiments on many dogs show that the treatment will remove 

 all the ascarids present in practically all cases regardless of vomit- 

 ing. If the bowels do not move in four or five houi*s it is advisable 

 in the case of sick or weak dogs to give another ounce of castor oil. 

 As already noted, it is dangerous to give chenopodium to dogs under 

 certain circumstances, and the services of a ATterinarian should be 

 obtained if possible to prevent accidents. The feces passed for the 

 two days after treatments for worms of any sort should be carefully 

 collected and Inirned or buried deep, as they have an unusually high 

 content of worm eggs. 



Carbon tetrachloride given in the same dose and manner as stated 

 for hookworms (p. 21) is also very effective in removing ascarids 



Fig. 16. — Eggs of dog ascarids ; a, 6 



ris limbata ; c, d, Belascaris marginata. En 

 larged. From Wigdcr, 1918 



