[Toxocarosis in dogs - important aspects for the veterinary practice].

The zoonotic roundworm Toxocara canis is considered one of the most common gastrointestinal helminths in dogs in Europe. Infection occurs via embryonated eggs from the environment or the ingestion of paratenic hosts. Pups become infected via intrauterine or lactogenic transmission of larvae from the bitch. Prenatal infection results in major consequences because the infected neonates shed large amounts of T. canis eggs into the environment due to a lack of immunocompetence and the resulting inability to fight the infection. After oral ingestion of the eggs, larvae hatch in the small intestine and penetrate the mucosal intestinal wall. Depending on the immune status and the route of infection, either tracheal or somatic migration occurs. Clinical symptoms of Toxocara infections in pups include gastrointestinal symptoms like the typical pot belly or rachitic symptoms. High worm loads might even result in ruptures of the intestine with the consequence of lethal peritonitis. The infection in humans as paratenic host may lead to the clinical pattern of larva migrans visceralis, larva migrans ocularis, neurotoxocarosis or the so called "covert" toxocarosis. Based on the zoonotic potential, information concerning the biology of the parasite and the necessity of anthelmintic treatment to effectively control T. canis in dogs should be provided for the pet owner. This may lead to better parasite control and decreased environmental contamination.