1) any remedies to help fix badly (maybe back into toe bed) split nail(s)?

2) " " avoid this in future?

3) " " for pain, and possible infection?

Dog is on a raw food diet.
Generally healthy.

Is licking and licking at the paw with the split or splits. Acts like it hurts him _a lot._

I am thinking hypericum perhaps for the pain to start with since it is nerve tissue related?

Have a look at Thuja 200C one dose and wait or 30C once daily for a week or two. Consider Silicea if he is very chilly and loves warmth. You could try Hypericum as well for the pain.

Apply Calendula topically, keep nail trimmed and make sure he does not jump down or up on anything of great height, like the bed, car, etc.

NAMASTE