Anthelmintic efficacy of thenium closylate-piperazine phosphate combination tablets against Toxocara canis in pups and young dogs.

Thenium closylate-piperazine phosphate combination tablets, tablets containing either thenium or piperazine, and control tablets (excipients only) were administered in 2 doses 5 to 7.5 hours apart to weaned pups and young dogs, in critical controlled trials to test efficacy against naturally acquired infections of Toxocara canis. In the 1st trial, the combination tablets produced a mean clearance of 94% from 18 pups. Tablets containing thenium alone showed a mean clearance of 9% from 25 pups, and tablets containing piperazine alone caused a mean clearance of 56% from 16 pups. Clearances, corrected for spontaneous worm losses observed in pups treated with the control tablets, were 90% (combination), 5% (thenium alone), and 52% (piperazine alone). In the 2nd and 3rd trials, efficacy of the combination tablet in 15 pups was 78% when corrected for worm losses in pups which had received placebo (excipient) tablets. Each component in the combination tablet contributed its full single-entity efficacy and, if in combination, synergistic effect between the components.