It's hard to give any advice, without more specific details. What exactly does "freaked out" mean? Did Kipper inflict any wounds on the other dog? Were there punctures, or marks of any kind? How long did the "freaking out" last?

In general, if your dog is that reactive to other dogs, I would stick to private playdates with dogs that you know he gets along with. However, Kipper could simply be a little over-zealous, but harmless, with his corrections. Some people can overreact to a dog growling and displaying, when it's often just for show, and no harm is ever done.