By contrast, untreated infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, pneumonia, enlarged abdomen, flatulence, poor growth rate, and other complications.

Several anthelmintic drugs are effective against adult worms, for example fenbendazole, milbemycin, moxidectin, piperazine, pyrantel, and selamectin.

The adult T. canis has a round body with spiky cranial and caudal parts, covered by yellow cuticula.

In dogs under 3 months of age, the larvae hatch in the small intestine, get into the bloodstream, migrate through the liver, and enter the lungs.

In dogs older than 3 months of age, the larvae hatch in the small intestine and enter the bloodstream, where they are carried to somatic sites throughout the body (muscles, kidney, mammary glands, etc.)

At the height of pregnancy, the encysted eggs in an infected female dog will migrate from the mother to the developing fetus, where they will reside in the liver.

Alternatively, the migrating larvae in the mother may encyst within the mammary glands, becoming active during lactation and passing directly to the nursing puppy via the milk.

[9][3] Transmammary transmission occurs when the suckling pup becomes infected by the presence of L3 larvae in the milk during the first three weeks of lactation.

Consumption of eggs from feces-contaminated items is the most common method of infection for humans, especially in children and young adults under the age of 20 years.

[15] Toxocariasis can result in complications such as hepatomegaly, myocarditis, respiratory failure and vision problems, depending on where the larvae are deposited in the body.

[12] In humans, this parasite can infect organs including the lungs, liver, and the back of the eye (which can result in blindness).

[16] Humans suffering from visceral infection of T. canis, the drugs albendazole, mebendazole and thiabendazole [citation needed] are highly effective.

Dogs sharing homes with young children or immunocompromised individuals: 12 times a year, if excretion of worm eggs is to be excluded.

Good practices to prevent human infections include: washing hands before eating and after disposing of animal feces, teaching children not to eat soil, and cooking meat to a safe temperature in order to kill potentially infectious eggs.