You can thing of horses as symbols that were pulled out of abyss to the light. After all, they are in comic "simply" because Hussie likes them. Yet, as they are brought to our attention, they gain meaning. So much meaning. Ultimately they are, on one hand a void symbol. And yet they show us the phenomena described by Rose. As Void is brought to Light. That eventually fades away to irrelevance.

See the thing is, do we just assume horses are relevant because of Hussie’s love of them? The choice for Frogs seems rather arbitrary, too, until you consider both Gnosticism and the Sperm + Egg comparison. So for all we know, Equus is more of a reason than simply Hussie’s love of them.

Also thinking on it there may be something about Knighthood? Striders are the closest to Hussie self-inserts, and they’re both tied to Horses, Dave through Maplehoof, and Dirk through… Dirk. Dave’s a Knight and Dirk’s a Prince that looks up to a Knight as an Ancestral Figure, and ends up acting like a Knight a lot. With all the chess Symbolism, there may be something here…