Cause and Transmission of Roundworm in Dogs

The cause of the medical condition in dogs commonly known as Roundworm is relatively simple. Upon infection with the Roundworm parasitic organism, a dog will exhibit the symptoms of this condition, and will then be able to be positively diagnosed for Roundworm by a veterinarian. In relation to Roundworm in dogs, there are two different species of parasite that may cause this condition.

Toxocara canis

The parasite known as Toxocara canis was first discovered in 1950, when a scientist named H.C. Wilder published a paper describing toxocariasis in humans. This parasite is primarily hosted in dogs, though it is most commonly seen in very young puppies. It's estimated that about 50% of all puppies, as well as 20% of all adult dogs are infected with this parasite. The incubation period of Toxocara canis may vary, and is dependent on both temperature and the humidity level. In ideal conditions, it's possible for Toxocara canis eggs to mature in approximately a two week period outside of their host. It's possible for Toxocara canis to remain infectious for several years, since they are fairly resistant to environmental changes.

Toxascaris leonina

This type of parasite is seen in many different animals, including dogs, cats, and other species. Once the eggs of this parasite are ingested, they usually pass to the small intestine, where they hatch. Juvenile Toxascaris leonina will return to the intestine once they are at their maturation stage. Female Toxascaris leonina worms will then lay eggs, most of which pass through a dog's system into the feces. The intermediate host of Toxascaris leonina is usually a rodent, which may ingest eggs that have passed through an animal into the fecal matter.

Transmission of Roundworm in Dogs

For a dog to become infected with roundworm, there are four common ways that this transmission may occur.

  • Consuming an animal that is hosting a Roundworm infection, such as a Rodent.
  • Nursing from a lactating female that is infected with Roundworm.
  • Being born in a litter of puppies from a female dog infected with Roundworm.
  • Consuming or being exposed to infectious Roundworm eggs, usually present in soil.

Once infection occurs, the life cycle, environment, and immune system response of the infected dog determines the severity of the infection. It's possible for a Roundworm infection to go unnoticed for a significant amount of time, before proper diagnosis from a veterinarian is obtained.