Packhorses
From The World of Dreams Manual
Horses/Packhorses
Tailors make the bridles for packhorses and packllamas, you use the bridle on the tamed horse or llama. Commands "Fetch" will drop what he is carrying, and if you say "Fetch" and open his pack, he will put the fetched item in his pack.
If you wish to remove the pack from the horse simply use any bladed weapon (dagger) on the pack.
