Durvet Thrush Rid®Usage Horses external use only on hooves. Benefits Works against thrush and aids in prevention of thrush Helps toughen soles and can be used under pads Long lasting Purple color shows where the product is working Ingredients P. V. P. Iodine Complex.. 2% Gentian Violet min 1%, max 5% Directions FOR USE ON THRUSH: Apply to affected areas then follow up as needed with application when color starts fading. A single application is often all that is needed.