Iona just wanted someone to hear about all the grief that he has been suffering from. He started talking to everyone that he came across but the problem was that no individual was either interested nor anyone had the time to hear what he was saying. Everyone was just focused on getting out to their own ways. He wanted to talk about everything, the way he died, how he went to collect the clothes of his dead son, how he has been feeling, but he was unable to find someone. This was the time when he resorted to telling everything to his horse. The horse being true to his master listens to everything and breathed over the master's hand, comforting in his own way.