Six-month feeding study of fenvalerate in dogs

Groups of six male and six female Beagle dogs were fed diets containing 0, 250, 500, or 1000 ppm fenvalerate for a period of 6 months. Prominent in-life observations related to treatment were emesis, head shaking, biting of the extremities, ataxia, and tremors. One high-dose male dog was sacrificed in extremis during the study period. Mean body weights of 1000-ppm female dogs were significantly lower than those of controls. Red blood cell counts and hematocrit and hemoglobin values in high-dose male and female dogs were significantly lower than those of controls at most sampling intervals. Serum cholesterol and alkaline phosphatase levels were also increased primarily in the high-dose group. Ophthalmic examination revealed changes in retinal vessel tortousity in some mid- and high-dose dogs. Hepatic multifocal microgranulomata were observed in control and treated dogs microscopically. These changes increased in incidence and severity with dose and were considered to be related to treatment. Histiocytic cell infiltrate in mesenteric lymph nodes in some 500- and 1000-ppm female and 1000-ppm male dogs was the only other treatment-related microscopic effect.