London Zoo: Stink happens: Self-anointing in animals

European hedgehogs produce a frothy saliva to mix with smelly materials they find such as soap, tobacco, cigarette butts, feces, chemicals used for cleaning, dead toads, or creosote. Then they spread the mixture all over their spines. This self-anointing behavior provides protection. Strong-smelling substances camouflage their own odor and perhaps make them disgusting enough to be unpalatable to predators.

Self-anointing occurs in many species, and there are multiple reasons for it. Rice-field rats self-anoint with the anal gland secretions of Siberian weasels, making it harder for these predatory weasels to detect them. Monkeys use millipedes crushed on themselves as a repellant against annoying insects and parasites. The chemicals in millipedes are bactericides, fungicides, and insecticides.