Sometimes it is hard to tell if dogs are being protective or not. Dante is a 72 pound GS and is a medium sized and is small than average GS. He is the same height as my Labradoodle but in length my Labroodle is longer. Anyways Dante is aggressive towards other dogs except for my own Labradoodle and my little dog Millie (Maltese mix). Dante is not fearless at all. Dante is so loyal and never leaves my side no matter what literally and is very affectionate and loves showering of affection and bonding activities buddy. On our hikes he is on leash due to he is not neutered. However, I have bumped into dogs I know from local dog park (coming and not coming anymore) even dogs I once walked or other dogs and he just lunges at them. He shows no aggression or growl. But he would do the attack unprovokly. I tell people to keep dogs on leash Dante is "dog aggressive", if I see a dog and not their owner I tell dogs to wait and stay until owners get them or I go another way if their is a two way path or whatever. I tell the owner about this quite often but is in denial that Dante is "dog aggressive" and blames the other dog often. Dante's owner seen Dante do this before. She thinks Dante has NEVER started the attacks or fights. I have said, "How can you be for certain?" Okay near the end of a long hike 2 months ago I saw a dog I once walked with the dog owner's grown children. I went up to him and there were two little dogs. The dogs were sniffing Dante a little black one I think was sniffing Dante and Dante attacked him holding his neck. Got Dante off immediately. He has been in my house several times and follows me everywhere. I went on a walk with Riley and Dante they get along great. Any dog for some reason gets along well with Riley and Riley never once been attacked by a dog. When I play he just sticks by me playing and goes plays with Riley but comes back after like 1 minute of playing. Run around with him throw balls I was playing with Riley simanteneously. Then Dante was watching Riley and I playing. I got too carried away and Riley started playing roughly making weird noises and Dante stopped him did NOT attack Riley just in dog language telling Riley to stop. I called Dante off and Dante did as was told. Been wondering why he did that. Sometimes if there is a dog like an aggressive chihuaua often loose on our street and comes at me like wants a chunk of me and Dante was with me and I was staring ready to protect me I think. Same thing with a terrier I see walking around sometimes Dante was staring ready to strike. I watch his body language well before he does something.