Phoenix is adorable! At five months of age, it is the time when his puppy teeth are falling out and his adult teeth will be growing in, so it could be that the tug of war is playing a part in these baby teeth being dislodged. That being said, you don't want anything to disrupt the growth of his adult teeth, so I would hold off on the tug of war for now. I'd also have him mouth checked by a vet just to make sure that the roots of the teeth have fallen out so that his adult teeth can grow in without problem. I hope this helps!