Tortoise Injury

My Desert Tortoise came out of hibination and I found him at my door with an injury on the tip of his shell.

I was at work so I don't know how many hours he was there. I believe that my dog did it.

I put Grapefruit extract in water on the sore, it is small but He isn't moving or putting his head out of the shell. I think he is alive he pulled his leg when I touched it.

I put a box with dirt in my house and put him in a quiet room what else can I do?