This paper introduces the teleonome as a unifying biological construct that clarifies the goal-directed organised system by which organisms engage in adaptive processes. The teleonome is the integrated system of perceptual, physiological, behavioural, and affective capabilities shaped by natural selection to enable survival and reproduction. In animal welfare contexts, it describes sentient animals as maintaining viability through affective evaluation, agency, and the exploitation of environmental affordances. As a descriptive framework, it does not prescribe what welfare ought to be, but it does identify why affective experiences matter to animals: they allow them to detect relevance, prioritise competing demands, and modulate behaviour and physiology over their lifetime. They act as signals and regulators to govern learning, motivation, and trade-offs. In animal welfare science, explicit teleonomic principles highlight the significance, not the mere presence, of physiological and behavioural indicators. The teleonome frames welfare of individual animals as a trajectory of adaptive regulation in dynamic environments, shaped by their inherited and epigenetic potential, and modulated by life stage, learning, current context, state, and allostatic load. We argue that mapping species-specific teleonomes alongside their affective profiles provides a principled basis for evaluating the comparative weight of different welfare concerns, improving assessments and monitoring, informing research design and ethical decision-making. The teleonome thus offers a framework for reconnecting data with the lived experience of all kinds of animals, and for building welfare science outward from what matters to them.