A 4-year-old dog was brought in for biting the owner’s hand during petting. The owner wanted euthanasia. A behavior-savvy vet observed the dog for five minutes. Each time the owner leaned over the dog’s head, the dog’s pupils dilated and ears flattened—signs of visual/orbital pain. An eye exam revealed a deep corneal ulcer. Treat the ulcer; the “aggression” vanished.