Anxiety assessment is the systematic determination of whether a companion animal is anxious, how severe that state is, and which situations elicit it. Its evidence base is twofold: owner-completed instruments validated for dogs and cats convert descriptions of everyday behaviour into quantitative scores for fear- and anxiety-related traits such as stranger-directed fear and separation-related behaviour, capturing relatively stable predispositions rather than momentary state[1][2], while salivary cortisol provides a non-invasive index of adrenocortical activity, although between-individual and between-occasion variation limits the interpretation of single samples[3]. Assessment must also separate anxiety from fear and phobia and identify the eliciting context, such as separation or noise[4].