The effect of corticosteroid therapy on infection with Toxocara canis in dogs.

Three, six-month-old dogs were infected with 2,000 eggs of Toxocara canis. Three weeks after infection 15 immature adult parasites were found in the intestine of the dog which had been treated with high doses of corticosteroids (2 ml of Opticortenol S given every four days) while no parasites were found in the intestine of the dog treated with repeated injections of 0.3 ml Opticortenol S or in the untreated control dog. The increased susceptibility to infection with T. canis in the dog treated with high doses of corticosteroids was associated with a decrease in in vitro lymphocyte responsiveness to the mitogen concanavalin A and pokeweed mitogen and with a complete suppression of the eosinophilia that was seen 10 days after infection in the untreated control dog.