UPDATE
The horse Apathetic gave me managed to escape by jimmying the bolt on it's new pen. What followed was a seven hour chase through the countryside dodging the arrows and bullets of the angry mob that had been patiently waiting outside the barbican gate. Afterwords we learned the value of friendship and good horse etiquette, which is a euphemism for "Woops, I accidentally crushed the horses ribcage in furious rage. I'm going to taxidermy and reanimate it so apathetic doesn't know I killed it. Later I'll bolt some copper plating onto it's interior and smuggle delicate objects and necromantic contraband inside it's hollowed out rib cage while riding it through the city streets disguised as a tax collector or a leper."