Help, theres a dog with an amptutated leg outside my house, what can i do?

we were in hurricane dolly and a lof dogs were outisde because the fences fell off, theres a dog outisde without a leg! i saw him earlier today and it did have a leg now it doesnt. its not bleeding its like burned or something..the poor dog does have a leash and it comes to me when i offer him food. what should i do? my dad says to leave i alone its not my business but the poor dog is suffering!! how much would it cost? im afraid i'll hurt him when i pick him up or something its a medium size dog... help??!!