In my opinion the relationship between humans and animals reveals that there are some levels of relations we can’t find among humans. I think is for that reason that animals can help humans to establish another kind of links with the environment.
When a person, kid or adult, with personality disorder, as autism or depression, is related to someone healthy, the relationship is unequal. One of them is superior to the other, both appreciate the difference: in gestures, in the conversation, then the connection is affected, becomes a hierarchical, intimidating relationship. Instead the inequality of the species keeps each one in its place, seeking only the points on connection, not divergence. I think this is the reason why the relationship between animals and humans is beneficial.
In the case of dolphins I have no doubt that also the fact that the environment is unusual and relaxing, the water, benefits the relationship.