I have a stepson who is almost 10 who remains very attached to a stuffed dog he received when he was 3. He sleeps with it, takes it around the house, and brings it to dinner. He realizes it's not the most appropriate behavior for a boy his age since he never brings it to school, or anywhere else he interacts with boys his age. But when alone with family, if the dog gets lost, he gets very weepy until we find him. His mom and I are wondering how we go about weaning him off the stuffed dog.
The best suggestion I can make is to allow him to wean himself at his own pace. I understand that he gets weepy and that this behavior has an impact on others in the family, but attempting to force him to let go of the dog is likely to be a frustrating and fruitless process (and may even cause him to cling more firmly to it). The reality is that over the course of the next year or two, he will likely let go of it on his own (and if he doesn't, who is it harming?). As long as it does not cause him or anyone else physical or emotional harm or prevent him or anyone else from accomplishing necessary tasks, it is probably best that you simply wait for him to do it on his own. In the meantime, should the dog get lost, it is ok to let him know that he alone will be responsible for finding it (if you feel this is necessary). Don't feel the need to rush to comfort him but don't belittle or minimize his emotions. Simply ask him if he's ok or if he needs anything and if the only thing he needs is to find the dog, you can then either choose to help him, or choose to let him find it himself. If his emotions are excessive or intrusive to others, he may need to spend some time alone in his room to self-soothe (not as punishment - just to give him time to self-soothe without impacting the rest of the people around him - he's free to come out once he feels restored).