One hundred and sixteen million equines are in contact with humans today and contribute to the flourishing or demise of our planet. The implications of the mental attributes attached to sentience are reviewed in the light of equine welfare and their environmental effects. A detailed assessment of sentient equines mental aptitudes points out that several mental aptitudes that have previously been considered unique to humans are present in equines. Several of these are discussed, including social contracts, moral agency, collective intentionality, and desire independent rea-son with examples from human equine interactions. As a consequence of these mental attributes, our mutual moral obligations are pointed out. An increase in the under-standing of equine ontology (their world view), can help humans delineate positive welfare in their husbandry, work and interactions with humans, but it will need humans to emerge from many traditional beliefs and practices. Simple summary More than 100 million equines are in contact with humans in the world all of whom contribute to the flourishing or demise of our planet. Equines are recognize at sentient but the mental attributes attached to sentience are not always recognized. They are explained and summarized here but they include some that are considered unique to humans (e.g. self-consciousness, social contracts, theory of mind, moral agency, collective intentionality, and desire independent reason). The implications of recognizing sentience for the moral obligations that both human and equines have to each other are outlined. As a result of this, their ontology (what it is to be) can be integrated into their husbandy and teaching, this is “positive welfare”. An example of a stud which has experimented with fulfilling these obligations is given. It is possible for humans to be morally justified in keeping working and interacting with equines provided changes are made to their husbandry to increase their autonomy, and training is cooperative. Only in this way will positive equine welfare and a flourishing living world be achieved.