PARASITES AND PARASITIC DISEASES OF DOMESTIC
Toxascaris leonina has the most straightforward lifecycle of the dog and cat ascarids.
Dog and cat definitive hosts may become infected in two ways:
- Ingestion of infective eggs containing second-stage larvae.
- Ingestion of intermediate hosts containing encysted third-stage larvae.
Since there is no somatic migration in dogs and cats, there are no prenatal or
transmammary infections. Mice, and to a lesser extent, other rodents and chickens,
may serve as paratenic hosts for T. leonina.