Attitude change about big dogs

Question
My beagle is a year and a half old. He has always played
well with dogs of all sizes. Usually, we have him in the
small dog side of the park, but we never had a problem
taking him to the big dog side to play if there were no
small dogs. But here recently, he acts completely terrified
of big dogs. He raises his hair, shows his teeth, and does a
shrieking bark, and then violently snaps at them if they
continue to get closer. Yesterday, he even attacked big dogs
that he has played with quite a few times in the past. He
still has no problem with small dog. He wasn't attacked or
anything like that. This behavior came out of nowhere. Any
idea on a reason for this unexpected change and how I can
get him to play with big dogs again?  

Answer
Hi, well first of all for safety sake he really shouldnt be with the big dogs, if one of those big dogs he snaps at decides he has had enough they could kill him just by the fact that they are so much bigger, and their bite will be more dangerous. And absolutely no way should he be over there if he is afraid or snapping at them, you are just inviting trouble. I don't know what could have caused this change other than some big dog spooked him. There is a reason for small dog sides and big dogs sides. Personally I would never take my dogs over to the big dog side even though they play with my son's pit bull at home and are ok with a big dog, you are taking a huge risk and the owners of the big dogs cannot be held liable for anything their dog does to yours. Remember there is a pack mentality when many dogs are together and the smallest and weakest are usually the prey, a small dog who is snapping out of fear will not discourage the ALPHA from coming after him...... please!!!! stop doing taking him over there for his safety and yours!