Abstract: A grooming brush adapted to dispense medicinal or pesticidal powder into the hair or fur of an animal through the action of brushing alone, having a handle and a head, the head having a top, a bottom, and four sides, the fourth of which is integral with the handle. The head is divided into a first and second chamber for storing and dispensing powder, the chambers defined by two partitioning walls. The bottom of the head has a plurality of bristles, an elongate opening which runs the length of the head, and a rotatable cylinder set into the elongate opening, the cylinder having a plurality of shallow depressions and a cog wheel with an circumferential border at approximately the tip of the bristles. When in use, the cog wheel engages the hair of the animal and the cylinder rotates alternatingly within the powder reservoirs and without, thus alternately collecting powder from the reservoirs and depositing it onto the animal.