Loss of a pet companion is always tough. I have lost cats and guinea pigs, and I'm sorry for your loss.

Lucid dreams with pets are possible. But have you though about non-lucids? We had to euthanize one of my cats and i had huge guilt about it. I still do. But once I had a dream about my cat spotting me, running to me and jumping up into my arms. It made me feel much better. As if I was forgiven.

This may not work on first try, but you can try to incubate a dream. As you falling asleep, think about your dog, imagine how you guys used to play and do things. Keep looking at his picture. Let that be your last thought before you fall asleep. You just may have a dream with him. good luck.