(OOC: That's correct, 40 for the dog and 40 for the encumbered horse. Encumbered dog + spell is 60 and unencumbered horse is 60, so one casting gives you 60...Although actually, if you could manage to get Rambler to stay lightly encumbered...oh wait, never mind, the spell can't target him.
Ah, you're right about Hewj. He could approach you guys or something realising he can't keep pace with a horse.)