Toxocara canis (also known as dog roundworm) is a worldwide-distributed helminth parasite of dogs and other canids. The name is derived from the Greek word "," meaning bow or quiver, and the Latin word "caro," meaning flesh. They live in the small intestine of the definitive host. In adult dogs, the infection is usually asymptomatic but may be characterized by diarrhea. By contrast, massive infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, an enlarged abdomen, flatulence, and poor growth rate. As paratenic hosts, a number of vertebrates, including humans, and some invertebrates can become infected. Humans are infected, like other paratenic hosts, by ingestion of embryonated T. canis eggs. The disease (toxocariasis) caused by migrating T. canis larvae results in two syndromes: visceral larva migrans and ocular larva migrans. Owing to transmission of the infection from the mother to her puppies, preventive anthelmintic treatment of newborn puppies is strongly recommended. Several anthelmintic drugs are effective against adult worms, for example pyrantel, fenbendazole, and selamectin. Morphology T. canis is dioecious, having morphology distinctly different between the male and female. Male worms measure 4 to 6 cm (1.5" to 2.3"), typically smaller than female worms who measure at 6.5 to 15 cm (2.6" to 5.9"). The male's posterior end is curved ventrally and the tail is bluntly pointed. The male has a single tubular testis. They also have simple spicules, which allow for direct sperm transfer. In the female, the vulva is about one-third the body length from the anterior end. The ovaries are very large and extensive. The uteri contain up to 27 million eggs at a time. Both males and females have three prominent lips. Each lip has a dentigerous ridge. The lateral hypodermal chords are visible with the naked eye. No gubernaculum is present. In both sexes there are prominent cervical alae. The adult T. canis has a round body with spiky cranial and caudal parts, covered by yellow cuticula. Toxocara canis is gonochoristic. The cranial part of the body contains two lateral alae (length 2 to 3.5 mm, width 0.1 mm). The eggs are brownish and almost spherical.T. canis eggs have oval or spherical shapes with granulated surfaces, are thick-walled, and measure from 72 to 85 μm. The eggs are very resistant to various weather and chemical conditions typically found in soil. Life cycle Eggs are deposited in feces of dogs, becoming infectious after