The control of Toxocara canis was investigated in naturally infected u
nweaned puppies. Anthelminitic treatments were administered to three l
itters of pups at 2, 4 and 6 weeks of age. When either a new combinati
on anthelmintic containing febantel, pyrantel embonate and praziquante
l or fenbendazole was used, the faecal egg output over the first 7 wee
ks 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 afte
r the 2 week dose and after the 4 week dose. Although worm numbers wer
e substantially reduced by treatment, there was evidence of significan
t reinfection taking place throughout the control programme. It is con
cluded that more potent anthelmintics can provide longer term benefits
by reducing the numbers of T. canis eggs shed into the environment, b
ut that multiple dosing remains essential for this purpose.