Figure 1.

Example of a facial image of a cat and response options available for cat caregivers completing an online survey containing 10 facial images of cats with different degrees of pain. Images were scored using the Feline Grimace Scale and the following instructions were provided: ‘For each image, please select the option you think is most appropriate for each action unit (AU). If an AU cannot be clearly seen, please select the option “Not possible to score”. You may refer to the training manual as many times as you wish’