Studies on the control of Toxocara canis in breeding kennels.

The control of Toxocara canis was investigated in naturally infected unweaned puppies. Anthelmintic treatments were administered to three litters of pups at 2, 4 and 6 weeks of age. When either a new combination anthelmintic containing febantel, pyrantel embonate and praziquantel or fenbendazole was used, the faecal egg output over the first 7 weeks of life was reduced by more than 80% and worm burdens by over 90%. In contrast, piperazine adipate had no appreciable effect on T. canis egg output, even though worm burdens were reduced by 86% by 7 weeks of age. In a further trial using three litters, the worm burden of pups treated with the combination anthelmintic was profiled before and after the 2 week dose and after the 4 week dose. Although worm numbers were substantially reduced by treatment, there was evidence of significant reinfection taking place throughout the control programme. It is concluded that more potent anthelmintics can provide longer term benefits by reducing the numbers of T. canis eggs shed into the environment, but that multiple dosing remains essential for this purpose.