ive posted a few comments about my border collie's tendency to be agressive towards other dogs but the other day i found out something new while walking through the park with her on a lead a man was walkin behind me with a border colllie and a springer spaniel it both were male anyway this spaniel was running off the lead around codey he would run up to her then run away i think he was kind of winding her up lol she was tryin her hardest to get at him she wasnt barking or growling just wanted to chase him but then he came up close and sniffed her face then her tail went between her legs and the fur on her neck went up she was like cowering up to me still with the fur up then she tried to bike him but i dont think it was meant to be hard just a snap does this mean she is scared of other dogs thats why she acts so agressive we have another bitch at home who is alot older and codey has no fear of her what so ever she plays with her and kind of bosses her about a bit lol but whats wrong with her?

Is she entire or speyed?  A male dogs approach can be a lot more full on, which can cause an undersocialised dog to become fearful - her reaction sounds very similar to my rescue ESS's reaction when approached.  Was Codey on lead too?  This can make a dog feel very vulnerable - my dog is a LOT better off lead around other dogs......

In the canine the fear and aggression occasionally seems to "come on out of the blue" but more often is triggered by getting into the dog's "space" or protective territory. This unsocial behaviour, while it may be "normal" if the dog  were interacting with another dog  to defend territory or signal "leave me alone", can be dangerous to people. Cats in this fear/aggression mode will bite and scratch...sometimes really terrorizing the owners. And dogs, with eyes glazed, teeth bared and with fearful barking and growling, will back owners into a corner or up onto a kitchen counter!  In dogs this is often referred to as RAGE SYNDROME and can be a very shocking event for the owner (and I suspect, for the dog as well).

Having lived for 7 years with a fear aggressive Alsatian(I can never bring myself to call her a GSD due to her breeding & behaviour & looks)fear aggression is horrific she would almost foam at the mouth & bare ALL of her teeth with a terrifying snarling akin to the behaviour of an aggressive baboon as it goes into attack if you have ever seen a wildlife program that is how a fear aggressive dog looks

I do not think your bitch has fear agression parsay I think she is simply frigthened of strange dogs & you need to enlist the help of a knowledgeable trainer & non aggressive stoodge dog(s) They key is for you not to react by pulling her away or trying to shut her up as she will perceive this as you indicating that her behaviour is ok

You could try distraction so that she stops perceiving other dogs as a threat or something to be frightened of & acceptes that their existance is not going to affect her or you