The range of animal practices potentially classified as medical varies widely both functionally and mechanistically, and there is no agreed upon definition of medicine that can help determine which cases ought to count as such. In this paper, we argue that all available definitions are fatally flawed and defend our own characterisation of medicine, which incorporates both functional and mechanistic constraints. We apply our definition to the available evidence and determine which animal behaviours show a mere difference of degree with paradigmatic medical practices—and should thus be seen as medicine proper—and which should be excluded from this nomenclature.