Maybe I was wrong?

[Georgygirl]

I always assumed that Roxie's lunging, barking, screaming at other dogs while she was on her leash meant that she was dog aggressive. Well, my bf took her to visit his family for a couple weeks where she met two female dogs, one of which wasn't spayed yet, and she got along with them just fine when she was let off her leash to see them. She had a great time playing with them. Is her barking and lunging on a leash just excitement then and not really aggression?

[Chewbecca]

could be excitement, or it could be leash aggression.

[Romy]

What does her body language look like? Does she ever "bow" down on her front legs while doing it?

[milos_mommy]

sometimes dogs feel "trapped" and unsafe when on a leash around other dogs.

[smkie]

Victor is very apprehensive when around aggressive dogs on a leash. He cannot outrun them and he knows it. Maybe it is fear.

[AgilityPup]

You know, it could just be her wanting to play... Bella does the same thing, and barks, but it's more of a "Rooo-roo-rooo" like silly play bark, then a "woof" back off bark..

Could be... Have you ever let her get close to the dogs she's being "agressive" at?

[Georgygirl]

I've never let her meet the dogs that she's barked and lunged at on her leash. Mostly because I thought she was acting aggressive and I didn't want to have an incident with a strangers dog. The two dogs she met and played nicely with were owned by family and friends of my bf so he knew more about them. They were also bigger than her so he was pretty sure she wouldn't be able to do too much damage to them before he could split up any scuffle that might happen. After a little tense introduction sniffing she was off playing with them. When she sees another dog while she's on her leash she usually pulls toward them or jumps toward them and barks her head off. If she gets really excited she'll even make this screeching like sound. I'm beginning to think that the leash has a lot to do with it, but I don't have a fenced in yard so she pretty much has to be on a leash when she meets other dogs unless its at the dog park, and I'm not sure if I trust her enough to meet the dogs at the dog park.

[RD]

The screaming and lunging could be excitement, but it also could be aggression when the leash is in the picture. My dog does not enjoy meeting other dogs when she has a leash on, but is seriously THE most social individual you'll ever meet when the leash is off.

[misticaleclipse]

A while back there was a chi where we lived, they metup with
my bf in the hallway of our apartment building and he said this
dog was growling, lunging and looked like he was going to kill
my dog!
So the owners says "he is only like that on leash" and takes
the dog off leash, and what do you know? She was right,
they got along great!

I don't know how to correct the problem sorry, but I am not
surprised now by this.