Louie did this once or twice. ... The first time it was because we lived out in the woods and some animals were scaring him . The 2nd time -We used a product called "Deter". Most pet stores sell it. Put tablet in food. We also changed his diet to a Premium dog food. As the new vet suggested maybe he was smelling "undigested food" (ICK) He hasn't done it for a LONG time since I did all this.