This is so funny, Catherine, and anyone who has lived with more than one dog knows how true it is.
For 15 years we had a Pekingese, now deceased, who thought he was the only dog in the family. He wasn't. At times there were one or two other dogs sharing his space. He ignored them. Completely. Totally. They did not exist for him.
Now, our Syau (one of the dogs that Chanelito ignored) has taken his place in the Ignoring Hall of Fame. She is the only dog now but when we adopted her, we also adopted her sister. Sadly, poor Sophie passed last year. Syau and Sophie were so devoted. With Sophie gone, Syau acts as though she is the only pet in the house (no other dogs but 2 cats) and the only dog on the face of the earth. At least Chanelito acknowledged other people's dogs. Syau may shoot a glare of disdain at another dog but there will be no butt-smelling, no sharing of bodily aromas. Dogs are so complicated!