Article content Calgary-based animal health technology company Sylvester.ai, in partnership with AI company AltaML and The Bar G, have developed an app called Tably that uses still images to tell whether a feline is happy or might be feeling pain. We apologize, but this video has failed to load. Try refreshing your browser, or New app can help read cats' behaviour Back to video The app looks at ear and head position, eye-narrowing, muzzle tension and how whiskers change to detect distress. A 2019 study published in peer-reviewed journal Scientific Reports found that the so-called “feline grimace scale,” or FGS, is a valid and reliable tool for acute pain assessment in cats.