Concurrent use of a colorant during drinking water treatment could contribute to the correct application of fluralaner to poultry. The present studies therefore examined whether the blue-colored drinking water conditioner Vac-Safe has an influence on the stability of fluralaner in water and/or on its efficacy for the control of poultry red mites (PRM).

Laboratory trials showed that fluralaner dissolved at various concentrations in water conditioned with Vac-Safe retained full stability for at least 27 hr at temperatures up to 40 C. Further, a field trial demonstrated that the efficacy of fluralaner in eliminating PRM from two infested houses of laying hens was equal when administered through drinking water with or without Vac-Safe. Consistently in both flocks, after treatment PRM could not be detected and sharp increases in laying percentage and produced egg mass were observed. It was concluded that Vac-Safe does not reduce the stability and treatment efficacy of fluralaner when administered simultaneously through drinking water.