If you're looking for something to aid in long term travel, you could make a low level buff (maybe 1st level) that can only affect animals and lasts 24 hours. Have it keep the animals from getting fatigued from forced marches, effectively allowing them to travel far in a single day, but their actual movement rate wouldn't increase, so it wouldn't make for a good combat buff.
I think with those limitations, you could pull it off with a 1st level spell.