My Rainbow Bridge baby, Sydney HATED other cats but loved dogs.
A neighbor once brought his new kitten over to meet him and Sydney hissed and growled at the poor thing and scared the heck out of it. After the kitten left, Sydney kept hissing at the spot on the floor where the kitten had been standing!
When my cousin would bring her dog over, however, it was playtime for Sydney. The two of them would run around together, playing and having a grand old time! They would even nap cuddled up together! Go figure.