Arboreal Sapling / Heal Animal

I'm thinking about making a Druid with an Arboreal Sapling companion (p 144, APG). For most animal druids, you would use Heal Animal (p 399-400 Core) to keep your companion alive, but Sapling doesn't have the animal trait. Does the druid with Sapling just lose usefulness from Heal Animal and have to blow regular slots to heal? Even if it isn't rules as written, would there be a problem with allowing Heal Animal to heal your companion sapling?

Since the whole thing about heal animal is to (mostly) keep your animal companion in shape I would allow it (and will for my players and npc)

but be sure to ask your own gamemaster