I think that their first intros are important. Robyn my female GSD generally likes all dogs, favors small dogs most of the time, but doesn't like one dog, another female GSD that is about the same age. The problem started in agility when the other dogs owner brought their dog over and she was right in Robyn's face, Robyn did not like that at all. After that Robyn didn't want to be near that dog and literally had a look of disgust when she seen her. I think that if the first intro was done right, butt sniffing and not in the face, Robyn would not have an issue wigh the other dog at all.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD