Dog recovering after a coyote attack him.?

He is home resting on ABX and pain meds I have to clean and irrigate the wound twice a day and keep an eye on him he is still weak and just lays around but I fed him and he ate, and he drinks at times so we are off to a good start, the vet said no major damage but he is just so lethargic and I was wondering how long it will take him to be himself again or do I need to worry about depression or will he ever be himself again?