Hi, 

Unfortunately, there isn't a cure for this or anything you can apply to help it heal. You can help protect it though. 

The tree looks like it is planted a bit too deeply, so removing some of the mulch and soil would be beneficial to find the root flare at the base. The trunk should come down and then flare out when it meets the soil, like the stem on a wine glass. Trees planted too deeply can develop girdling roots as they grow which can eventually wrap around the trunk and strangle the tree. 

For deer protection, you can fence the tree so that deer cannot reach the bark. If you were to put one around the mulch perimeter, that should keep the deer away as long as they can't reach over it to get to the trunk. It may need to be high enough so they can't reach over. There are also various trunk guards to help protect trees during deer rub season. Just make sure they are not too tight around the trunk as the tree grows and the bark has air flow to callous over the wound. 

If there are dry periods this winter and the ground is not frozen, it will be helpful to supplement water for the tree to help with any root stress from this past year's drought and high heat conditions. 

Next spring, look for any canopy dieback when it flowers and leafs out, as a sign that the tree isn't recovering well. 

Emily