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=Overview=
=Overview=
''Toxacara canis'' is a typical ascarid nematode that infects dogs where its predilection site is the small intestines. These worms can be found throughout the world with varying prevalence. Control of this ascarid is typically difficult due to its extended persistence in the environment. ''T. canis'' is also important in humans medicine as the species most responsible for '''visceral larval migrans''' (VLM). The human is a non-permissive host of ''T. canis'' meaning it cannot complete its life cycle and reproduce, however the larval stages do migrate through the human body causing pathology.
''Toxacara canis'' is a typical ascarid nematode that infects dogs where its predilection site is the small intestines. These worms can be found throughout the world with varying prevalence. Control of this ascarid is typically difficult due to its extended persistence in the environment. ''T. canis'' is also important in humans medicine as the species most responsible for '''visceral larval migrans''' (VLM). The human is a non-permissive host of ''T. canis'' meaning it cannot complete its life cycle and reproduce, however the larval stages do migrate through the human body causing pathology.
=Identification=
=Identification=
''Toxacara canis'' has the typical gross morphology of an ascarid, it is a large, fleshy white worm and can be up to 18cm long. The females are longer than the males who can normally reach 10cm in length. Microscopically ''T. canis'' has a fairly standard [[:Category: Ascaridoidea|ascaridoid]] appearance, though the adult head is given an elliptical shape by large alae or 'wings'.
''Toxacara canis'' has the typical gross morphology of an ascarid, it is a large, fleshy white worm and can be up to 18cm long. The females are longer than the males who can normally reach 10cm in length. Microscopically ''T. canis'' has a fairly standard [[:Category: Ascaridoidea|ascaridoid]] appearance, though the adult head is given an elliptical shape by large alae or 'wings'.
=Life cycle=
Typically of an ascarid ''T. canis'' has larvae have a migratory life cycle that is significance in the pathogenesis of infection. This species also has the most complex life cycle in the Ascaridoidea superfamily. There are four different life cycles that can occur dependant on the circumstances that the larvae or adult encounter.
==Cycle 1==
This is mostly a typical ascarid life cycle and commonly occurs in dogs that are infected between 2 and 3 months old. The infective eggs contain L3 larvae which hatch in the small intestine of the host dog after being ingested. The larvae then enter the hepatic portal vein and travel through the liver and further to the lungs where they moult to L4. The larvae then migrate to the trachea where they are coughed up and swallows again by the host. On returning to the small intestine they undergo two further moults before becoming adults.
==Cycle 2==