Toxocara canis is a parasite that affects young dogs and foxes. It has the same general muscle structure as the rest of the nematoda phylum. However, they are unique because they have a system of entering the body of young animals through different ways. They can come from the ingestion of eggs, the transfer of larvae from the mother's milk to the pup, or the transfer of larvae from the uterus of the mother to her unborn pup. Once the pup is born, it will have the larvae already inside its lungs and throughout its small intestine. They travel very quickly throughout the body using the circulatory system for transportation.
http://www.youtube.com/watch?v=XyJK9pZ9szU
http://www.capcvet.org/capc-recommendations/ascarid-roundworm
http://www.peteducation.com/article.cfm?c=2+2090&aid=762
http://www.capcvet.org/capc-recommendations/ascarid-roundworm
http://www.peteducation.com/article.cfm?c=2+2090&aid=762