Toxicology studies conducted in laboratory animals and cattle with coumaphos flowable formulation.

A new flowable formulation containing coumaphous, an organophosphate compound, will be used as an insecticide on cattle. It was evaluated for human and cattle safety. The oral LD50 for female rats was 37 mg of formulation/kg and the dermal LD50 for male rabbits was 500 mg/kg. The inhalation LC50 in female rats was 303 micrograms/L. Dermal sensitization in guinea pigs or eye irritation in rabbits were not observed. The formulation was a mild dermal irritant on rabbits, but the erythema reversed itself within 7 days. Spray safety evaluations in cattle included a single application, 2 treatments at 14 day interval, and 2 treatments at 28-day intervals with both 0.5 (highest label rate) and 2.5% (5X) concentrations. Dip vat treatments of cattle included 2 applications at a 7-day interval in 0.3% (highest label rate) and single applications with 0.6% (2X) and 1.2% (4X) concentrations. The cattle did not show significant clinical signs of toxicity nor did trends develop in clinical pathology. The lowest whole blood cholinesterase mean value for cattle sprayed once with a 0.5% concentration was 80% of the pretreatment value at 14 days post-treatment. The cattle receiving 2 dip vat treatments of a 0.3% concentration at a 7 day interval had their lowest cholinesterase reading (53% of pretreatment value) 10 days after the second treatment. Cholinesterase depression in cattle receiving higher than use rate treatment was related to the concentration applied.

Praziquantel for control of Hymenolepis nana in mice.

Praziquantel was blended into ground mouse feed at 35, 70, and 140 ppm in one replicate and at 140, 210, and 280 ppm in a second replicate. Mice naturally infected with Hymenolepis nana were provided this diet for 7 consecutive days. Reduction of Hymenolepis nana in mice receiving medicated feed when compared to mice receiving nonmedicated feed was 48.9, 73.2, and 87.1%, respectively in replicate 1, and 100% in all three groups in replicate 2. These data suggest that praziquantel blended into the feed at 140 ppm for 7 consecutive days will provide efficacious (87.1-100%) control of Hymenolepis nana in mice. Higher dosages may be necessary for complete elimination of this parasite.