Poor baby, I hope he's ok.

Those ants can be dangerous. Buffy was bitten not too long ago and my daughter had to rush her to the vet. She gave us quite a scare since her face was totally swollen. She was given antibiotics and kept in observation for a couple of hours. For a dog Buffy's size, being bitten could have been deadly. We'll need to be more careful when she goes on the grass from now on.