Our dog rubs his butt on the rug what is going on here?

This can be caused by many things... allergies, rectal irritation from having loose stools, intestinal parasites or anal gland problems. It’s most often related to the anal glands (they are located on each side of the rectum). They sometimes fill with fluid and the dog tries to relieve the discomfort by scooting on the ground.

A visit to the vet is in order. I would tell the vet what is going on and just to cover your bases I would suggest taking a stool sample in for analysis also.

I hope this helps.

Cindy