Vectra 3D remains effective for a full month if your pet is immersed in water through swimming or regular bathing. Make sure your dog is completely dry before applying the product, and let it dry completely after application before bathing. Do not use a detergent or dish soap, as this will remove Vectra3D and result in loss of protection. If using therapeutic shampoos, this may affect duration of action of Vectra 3D.