Dogs get roundworms mainly through several routes:
- From their mother: Puppies often get roundworms before birth through the placenta or after birth through their mother's milk. Infected female dogs can pass dormant larvae during pregnancy, infecting the puppies even if the mother was previously treated.
- From the environment: Dogs can ingest roundworm eggs that are present in contaminated soil, plants, or objects where infected dog feces have been deposited. These eggs can hatch inside the dog and mature into adult worms in the intestines.
- By eating infected animals: Small animals such as rodents, birds, earthworms, or insects may carry roundworm eggs or larvae without being the parasite's normal host. When dogs eat these animals, the larvae can mature into adult roundworms inside their intestines.
Additionally, dogs can ingest eggs by grooming themselves if roundworm eggs stick to their fur.
In summary, dogs get roundworms by vertical transmission from their mother, by ingesting eggs from contaminated environments, or by eating infected intermediate hosts. Puppies are most commonly infected through their mother, and older dogs usually get infected from the environment or prey animals.
