Ears pulled back? Nose bulging? Eyes squinting? Get some morphine for that mouse, stat. The first animal "pain face" scale, published in May by neuroscientists at McGill University in Montreal, measures the agony of lab mice. After giving mice a mild stomachache-inducing drug, the researchers recorded changes to five facial features, such as squinting eyes and bulging cheeks, which they combined to produce a 1-to-10 scale. They then verified it with more than 100 other mice, and it correlated with the degree of pain administered. Replacing conjecture about animal pain with an objective scale could help researchers more accurately test compounds in animals in order to develop better painkillers for a species that's already well-known to grimace when hurt: Homo sapiens.