A composition for killing an animal, e.g. a rodent, comprising: (i) a toxin component comprising one or more agents toxic to the animal, e.g. cholecalciferol or 25-hydroxycholecalciferol (vitamin D3)； and (ii) a carrier system for the toxin component； wherein the carrier system (ii) comprises: (a) at least one solvent or dispersant for the toxin component, e.g. an alcohol such as ethanol, and (b) at least one dermal disruptant component, e.g. dimethylsulfoxide (DMSO). The compositions provide enhanced dermal penetration of the toxin into and through the skin of the animal onto which the composition is sprayed or delivered, e.g. in a trap or other apparatus.
