
The trouble is Kelly, anything you say, is likely to fall on deaf ears. As you have recently told them exactly what you think, along with your OHs comments and they have still not made the effort then it wont change anything.
Could they not employ a dog walker? At least that way, the dogs will get some interaction and freedom from their boring existance. I know that they have kids, but it really is no excuse to neglect the dogs needs. If they can't look after them, then they should rehome them. I can't think of any other solution.
it's a bad idea calling the RSPCA, as you say, they wont do anything if the dogs are fed and sheltered and there is always the possibility that they will guess that it was you and this could cause very bad feeling all round. If it was me, I would try and have another word with them, using all the tact that you can muster, and point out
again the reasons as to why you feel that they have to change.
Sorry I couldn't be of more help, it's a horrible situation, especially when you have to see it everyday. :(