EFFICACY OF FENBENDAZOLE AND PIPERAZINE AGAINST DEVELOPING STAGES OF TOXOCARA AND TOXASCARIS IN DOGS

In a series of controlled trials involving 59 naturally infected greyh ounds, fenbendazole at a dose rate of 50 mg/kg/day for three consecuti ve days reduced the overall numbers of third and fourth stage Toxocara canis by 94.0 per cent and third stage, fourth stage and immature adu lt stages of Toxascaris leonina by 92.4 per cent. In contrast, piperaz ine at 100 mg/kg had little or no useful effect against the larval sta ges of T canis and T leonina and variable efficacy against immature ad ult T leonina. Fenbendazole was also 100 per cent effective against im mature Trichuris vulpis. In a separate controlled experiment, puppies in three litters exposed to reinfection with T canis were treated with fenbendazole at two weeks old and again only after their mean faecal egg counts exceeded 200 epg. Between one and three doses were required to suppress the output of eggs during the puppies' first 12 weeks of life.