I was wondering what this symbol (+) beside my wolf's name (Shale) meant?

She doesn't have any injuries and as far as I can tell there's no difference between her and my other wolves (outside of her Wisdom boost, which I don't think impacts this.) She is a hero, but this symbol doesn't appear beside the name of the other hero I have.

Sounds like you may have given them an explore boost or feather of some sort.

Hmm, how long do feathers usually last on wolves? The only ones I recall using (beyond robin feathers) on my females are ptarmigan. I don't believe I've used any other items on them.

I don't quite recall which items give a temporary explore boost unfortunately.

Snowy Owl feathers give a battle boost for 20 moves.

Various Chrysalis also give various boosts for 20 moves.

I'll keep an eye on it then and see if it disappears after a while of exploring. Thank you!

EDIT: Yep, looks like I put something on her and forgot about it. It seems to have disappeared with a bit of exploring.