[Concerning the toxicity of parbendazole (Helmatac 30) to horses and ponies (author's transl)]

The toxicity of parbendazole in different doses was investigated with 52 horses and 16 ponies, in twelve groups. Side effects observed with the anthelmintic were laxation (soft dung, diarrhoea), anorexia, and listlessness. The seriousness of these symptoms depended greatly on the dose used. Half the therapeutic dose of parbendazole (2.5 to 3.75 mg/kg) administered on two consecutive days led, as a rule, to only slight toxic symptoms and proved highly effective with regard to gastro-intestinal nematodes occurring in horses and ponies. The utilisation of "standard powders" (not commercially available as such) is recommended for simplified dosing (and thus preventing overdosing as far as possible). The laxative side effect of parbendazole was greater during the performing of work (movement). This investigation involved eight Shetland ponies in foal. The pregnancy varied between four and eleven months. No unfavourable effect on the gravidity or on the development of the foetus were observed. Neither clinical examination nor clinical chemical serum examination gave any indication of the occurrence of hyperlipaemia after treatment with parbendazole.