PARASITES AND PARASITIC DISEASES OF DOGS 



19 



the other Toxocara cati. The latter species is the more common and 

 is very similar in appearance to T. canis. 



The female worms produce numerous eggs (fig. 16) which pass out 

 in the feces and develop under favorable conditions of warmth and 

 moisture, in the course of 2 or 3 days under very; favorable condi- 

 tions, to the stage where each egg contains an infective embryo worm. 

 When such eggs are swallowed by dogs in contaminated food or 

 water or in other ways, the eggs hatch and the young worms enter 

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

 and finally many of them get to the lungs, usually by way of the blood 

 stream through the liver and heart. In the lungs 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 pregnant 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 derangements of the 

 appetite and digestion, and 

 heavily infested pups become 

 unthrifty and emaciated and 

 may die if the condition is not 

 reheved. When present in 

 large numbers the worms may 

 form masses which produce a 

 stoppage of the bowels, they 

 may wander into the ducts of 

 the hver, into the stomach, 

 causing the animal to vomit 

 the worms, or may crawl up ,^ 



the esophagus and enter the FionEE lO.— Eggs ot dog ascarids: a, b, e, Toxasmris 



lungs or nostrils. The young '^°g^^'_ i^V '*' ^'"''""''' ""'''■ ^""^^'sei- ^""^ 

 worms leaving the blood and ' i 



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 history of passing worms or when they are 

 known to have been associated with older dogs infested with worms. 

 The symptoms of roundworm infestation in cats are about the same 

 as those for roundworm infestation in dogs. Bloating and evidence 

 of acute abdominal pain are the usual symptoms of roundworm infes- 

 tation in kittens. Diagnosis is best made by a microscopic examina- 

 tion of the feces and the finding of the eggs (fig. 16). This examina- 

 tion 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 gelatin capsules at a dose rate of one-fourth fluid 

 dram (1 cubic centimeter) for a dog. weighing 22 pounds (10 kilo- 

 grams). This should be immediately preceded or followed by 1 



