I am going to have to agree with Cali and Shelteez on this one. (Maybe it is a dog sport people thing)

My Clover has never had a bad experience with Rottweilers but goes completly beserk when she see's one, It can be next to her in an Obedience class or on the other side of the park it does not matter. I now refuse to race her against Rottys in Flyball after she went after one.

Blue merle Cocker Spaniels are another hate and she has never been attacked, growled at or even barked at by one. We see ALOT of this thing in Flyball and our poor Boxers are realy hated by alot of dogs. (One who bit a child a few weeks ago and was not reported)

Clover also adores GSD it does not matter if she has ever met the dog, she just loves them and can spot a GSD amongst a group of mixed breed dogs from across the park.

Penny hates black Labradors again no bad experiences.

Elvis is supprisingly not keen on other Border Collies. And loves black Labs.