What would you do?

A neighbor on our street has a sweet golden retriever and my husband and I aren't sure what to do. I don't think any of these issues are technically neglect, but it just makes me sad. Here's what's wrong:

- he's got rampant fleas. You can see them running all over his tummy and he's always scratching.
- there's some kind of infection on his face, doesn't look too bad but not great either. I'm sure he hasn't been bathed in months.
- always left outside, most nights they open the garage door and he sleeps there.
- they do not walk or exercise him. We've been her a year and have never seen them more than pass him by as they walk in after work.

He basically just sits in their yard day and night. The fleas and possible infection worry me. He's obviously not being well cared for. We've chatted with these neighbors once or twice but they also don't speak a lot of English.

Any suggestions?