Just as stated above
Hackles up does not always mean ready to fight. It sometimes means a dog is unsure of something, and the hair stands up when they check it out.
Mine have also been known to do it during play. Their hair will stand up, and then they pounce in play mode.
Most of the time dogs read each other better, than we can read them.
Try and watch all the body language, and not focus on just one part.
That is unless he has a certain cue, that lets you know he's not okay with a dog.
In the past Cash would have every muscle tight, and stare directly at a dog. If he didnt want to interact with that dog.
June looks as calm as can be, but her eyes turn dark, if she thinks another dog has crossed the line.
Ranger turns his head away in avoidance, if he doesn't want to play with a dog. A low rumble if they push him. I can sweet talk him over to me, and normally 10-15 minutes later he thinks the new dog is fine.
Shine is still young, and thinks every dog should want a kiss on the mouth, and to play with her. She's learning about other dogs cues, but still has a ways to go.
Not all those who wander are lost.
Life is just a leap of faith.
Spread your arms and hold your breath and always trust your cape.
Two things define you. Your patience when you have nothing, and your attitude when you have everything.