SummaryThe aim of this investigation was to examine whether the treatment of bitches with doramectin is able to prevent pre‐natal and galactogenic infections withToxocara canisin their pups. Five experimentally infected beagle bitches were treated subcutaneously with 1 mg doramectin per kg body weight on each of days 40 and 55 of their pregnancy. Another infected bitch served as an untreated control. The efficacy of the medication was examined by counting the intestinal stages and somatic larvae in bitches and pups.The treatment did not completely prevent perinatal infections withT. canis. Intestinal stages and/or somatic larvae occurred in 16 of 20 pups. Seven pups developed patent infections. Compared to the control pups, the average worm burden (intestinal stages) of pups from treated bitches was less than 1 %. No impairment of condition or physical development was noticed in the pups during the investigations. From the second week of life, the pups of the non‐medicated bitch showed signs of a severe toxocarosis. No side effects were seen in the bitches after treatment with doramec