Plasma levels of fenbendazole metabolites in buffalo and cattle after long-term intraruminal administration. 
Plasma metabolite levels were measured in buffalo and cross-bred cattle after daily intraruminal administration of fenbendazole at 0.5 mg/kg body weight.  An equilibrium between the absorption of fenbendazole and disposition of its metabolites could be observed between days 3 to 6 and remained almost unchanged thereafter.  The buffaloes had a lower uptake of the anthelmintic and lower plasma levels of its metabolites than in cattle.  The findings were compared with those obtained after a single intraruminal therapeutic dose of fenbendazole.