Based on neurobiological evidence it is shown that indispensable behaviours like exploration and grooming are displayed because of their rewarding properties. Endogenous opioids play a pivotal role in rewarding the individual and motivate it to perform these behaviours, irrespective of the short-term biological success of such indispensable behaviours. Equine allogrooming and play in domestic groups have been addressed to assess whether they fulfilled the four ethological need criteria: (i) performed by all individuals; (ii) self-rewarding; (iii) have a rebound effect and (iv) in absence of a proper substrate (i.e. social partner) chronic stress is induced. Indeed it was assessed whether equine allogrooming and play are ethological needs. Not only in domestic non-voluntarily composed groups but it is evidenced why it is also an ethological need for individually housed sport horses. Summarising: social relationships and interventions especially in relation to preferred partners, have rewarding properties in the brain and seem therefore important for the main coping mechanisms of domestic horses in large groups and most likely also for feral horses.