I would say nothing. People like this will just figure the dog went off to die, and go get another dog. I think you should mentally prepare for the idea that there will be one more neglected pet at the house.
I don't think you owe them an explanation, but if they ask you could say something like "we saw her by the pond a couple of days ago, and she was in pretty bad shape". It has the advantage of being completely true, just not the whole truth. If they ask more questions, you can decide what you want to say. I don't think they will ask. It won't be that they don't care, it will be that their mindset says she went off to die by herself, and now they can get a new dog.
I applaud your dh for doing the right thing, and putting the poor dog out of it's misery.
I don't think you owe them an explanation, but if they ask you could say something like "we saw her by the pond a couple of days ago, and she was in pretty bad shape". It has the advantage of being completely true, just not the whole truth. If they ask more questions, you can decide what you want to say. I don't think they will ask. It won't be that they don't care, it will be that their mindset says she went off to die by herself, and now they can get a new dog.
I applaud your dh for doing the right thing, and putting the poor dog out of it's misery.