strange foaming at the mouth

Teenie certainly did, so I'd say it's possible. She did it mostly when she was tired (from exersize or acting out). It is drool, just not in the slippery liquid form, LOL 

yup. i'm pretty sure it's a sign of stress. honestly, maybe the dog park isnt the best solution for socializing your dog, with him having slight dog agression issues. maybe some slightly more controlled environment. i hear training class is an excellent way to socialize... :)

It's funny but I've only imagined dogs infected with rabies to do that like in the Old Yeller.  My dog never drools, she pants when hot, but no drool.  The foam is very white and very noticeable I try to wipe it before anybody sees it but it just keeps on coming.  It looks a little scary on a black dog. The dog doesn't really act stressed, she runs around and sniffs other dogs and plays with them.  She does avoid some dogs. Maybe it's to scare other dogs from her rabied self? lol. We don't go to the park anymore though.

I agree that the dog park is not a good solution for trying to fix this behavior.

You have to consider the other dogs who are there trying to enjoy themselves.

Having your dog on a leash with so much stimulation around is actually causing your dog to be more anxious around the other dogs and is ultimaltely doing more harm then good.

Your dog needs to be desensitized to the presence of other dogs.

What kind of previous socialization has your dog had? Meaning what did you do with him as a puppy?

You could start by grabbing a pocket full of treats and walking to the dog park. As soon as your dog starts to display this behavior you should stop, put him in a sit and give him a treat for his attention. Wait until he calms down......this could take a while. Keep distracting him with the treats until he reaches a calm state then go home.

The next day try to get a little closer......so on and so forth and reward him with treats to distract him and keep him calm.

This exercise should be done when your dog has had a bit of time to release pent up energy so he isnt at full throttle. Exercise him at home or away from the park before you attempt this.

i think i know what you mean about him not acting stressed. but some types of stress are pretty hard to read in a dog and the foaming would be one indication. of course i could be totally wrong. kinda hard to tell over the net, ya know.

i have a dog with fear related dog agression issues as well. as for me, i juat gave up the whole dog park type of situation. we dont have dog parks here, but downstairs of my apartment complex is a similar situation where most dogs are unleashed. i just try to take them outside when other dogs arent there and when we encouter off leash dogs i carry him, so he is removed from the situation (some people argue, that makes things worse, and i guess it might be true for some dogs, but it has proven to work well for me, and actually helped him a lot). on walks we do the same, and all i ask of him is to calmly walk past other dogs, as long as they dont come up to him. i think that is a more realistic goal and once you have achieved that (your dog ignoring other dogs) you could go from there and see how much more you can achieve, given a safe environment...

anyways, i know what it's like and it's a pain.. i feel for you! :)

I would bet this is stress related.  Perhaps you could take the addresses and phone numbers of a few of the dogs at the park that she does play with, and set up play dates.  It sounds as though she'd be more social and less worried in a smaller or quieter group of dogs.