And there is always that chance with any decision we have to make for our pwd however it may also be the natural decline of the illness that may bring changes anyway. I think you perhaps have to ask yourself again .... is there any other option in this situation from what you have described...and the answer will still be the same however harsh an action it seems you made it from sound reasoning for dog and your mum.In moderate dementia dad whilst obviously extremely distressed and traumatised by the sudden death of mum in their home adjusted as the months went by probably because he declined and on a different level I had to sell his much loved car from under his nose that he constantly kept checking on during the day and night to make sure it was still on the drive...after a couple of weeks he stopped looking and forgot about it.