alexbug:

Don't apply sealant or try to wrap the damaged area of your trees. This would be more likely to hinder than help them recover. There is a high likelihood that the little trees will recover completely in one season on their own. Insulation from cold is not a consideration.

I have had young apple trees 3/4 stripped by buck deer with that unfortunate habit of antler rubbing, and they recovered fully. Now, several years later, you can't even see where the rubbing occurred.

You have already done all you can by installing wire cages, now it's just wait and see. Bad dog.

Don Yellman, Great Falls, VA