Pro-Force 50 Spot-on offers a great option for horse owners looking for long-acting fly control. Sensitivities can occur after using ANY pesticide product on animals. If signs of sensitivity occur, wash the area with mild soap and rinse with large amounts of water. If signs continue consult a veterinarian immediately. Do not use on horses intended for food use. Not for use on foals under three (3) months of age. Ready to use, no dilution necessary.