Barking at certain dogs in certain situations

[Bubblemoon]

We've had our rescue 3 year old JRT cross 6 months ago and she's doing brilliantly. Recall 95% now, very obedient, very friendly with most other dogs we meet.
The two remaining issues we have are her being possessive and barking like mad if other dogs get too near me (if I try to pet another dog, even one she likes, she goes ape) and barking like a maniac, really shrill fear barking, if we see certain other dogs. Any dogs vaguely looking like a dogue de Bordeaux or a husky send her into a barking frenzy - even if they're across a busy road. They are huge compared to her, so I kinda see her point but I'd like to help her over this if I can, not least of all because it might get her in trouble in future. I've tried ignoring, distracting, avoiding and rewarding her when she is quiet. Also we're working on her possessiveness with me, we practice commands and work on obedience daily. Any tips to help speed the process would be really welcome.

[Bubblemoon]

Charlearose Loads of brilliant stuff there, thank you. I'd always just assumed it was my dog being small dog syndrome shouty, but she is very alert and so maybe quicker to bark. I've concentrated totally on her (not hard when she's going ape!) but now I'll stand in front of my dog and pay more attention to the other dog. The ddb lives between us and the park, so we're gonna have to get over this somehow!

[Bubblemoon]

You have something there with the harder to read faces of certain dogs- it's maybe no coincidence that it's the dogs with wrinkles and very furry faces that set her off! The guy with the ddb is a lovely chap, so I might ask him if he would mind a joint on lead walk - it'll either cure my dog or well all be deaf afterwards. Thanks for your help, you've inspired me to go get a book on doggy body language.