Toxocara canis and Toxocara cati are intestinal helminths of, respectively, dogs and cats. Both Toxocara species have, because of their zoonotic significance, important public health consequences. Prevention of infection with Toxocara eggs is based on education (general public, veterinary practitioners and physicians), hygiene and deworming of pets. An overview of the literature of Toxocara infections in dogs and cats and human toxocarosis is given. Little is known about the prevalence of the infection in the different categories of dogs and cats which is a prerequisite to give adequate information. Surveys in the Netherlands are described among privately owned dogs and cats and stray cats, dog breeding kennels and catteries to determine patent infections in dogs and cats and environmental contamination with Toxocara and other nematode eggs in breeding colonies as well as eventual risk factors for infection. Activation of somatic Toxocara larvae followed by a tracheal migration and the development of a patent infection is suggested for cyclic bitches during metoestrus. If this group of animals can be considered as risk factor is investigated by monitoring a group of intact beagles over a two year period by regular faecal examination and determination of serum Toxocara titers during the period following each oestrus. This was compared with similar observations in pregnant bitches. Deworming is considered as an important tool in the treatment of patent nematode infections and the prevention of environmental contamination with Toxocara eggs. The anthelmintic efficacy of oxibendazole against intestinal nematodes of dogs and cats is investigated in a field study among dogs, cats and puppy litters with emphasis on the suppression of egg shedding by young animals. Finally the knowledge of Toxocara epidemiology by veterinary practitioners, physicians, pet owners and non-pet owners is investigated to get a better understanding of the current practices of education and the need for specific information. The effect of the ...