A Companion from a series of books by Mercedes Lackey, Kantor does look like a horse, but is actually a guardian spirit returned to earth in this form. Companions are partnered with people called Heralds, who are like traveling magistrates/tax collectors/census takers/etc. The bond between Companion and Herald is extremely strong and intimate, usually with a telepathic link forming between the two. The death of one is very hard on the other. Kantor is Companion to Herald Alberich. The Valdemar Saga, as the series is called, is facinating and a treasure trove of imagery that any artist can take inspiration from. Companions are pure white with startling blue eyes. Pencil on computer paper.