Looks like a greyhound mix to me.
greyhounds and whippets are usually sweet dogs.
Definitely Greyhound/Whippet in there, as all have said. How tall is he?It looks like the mix is possibly with a hound of some sort, like a fox hound or beagle, possibly.
Taking a ruff guesstimate based on the high chair in the pictures I would have went for a greyhound with a touch of beagle given the shape of those ears Great dog a friend of mine helps out a retired racing greyhound charity she says they are lazy beggars who will chase a ball for ten minutes then spend the rest of the day sleeping on the couch