If your dog is the one causing the issue, shouldn't it and you be the ones who leave? Barking, growling and howling at another dog for no reason is not a normal reaction and there's no such thing as a friendly growl.
Dog parks are risky places at the best of times and when there's a known reactivity issue, even when it's just a certain type of dog, you must accept that these places are off limits because of the risk your dog poses.
I get really tired of hearing excuses like "he only does that to small dogs/large dogs/black dogs/people wearing red" as an excuse when a supposedly friendly dog attacks. This is of small comfort when it's your dog who was the small dog/large dog/fluffy dog doing nothing wrong who was attacked and injured.
You know that your dog does not like spaniels. Don't put her in situations where she could encounter them offleash where things could get out of control.
Well there has only been two spaniels which have came into the dog park - the first one she did not go near at, she barked and growled from a distance but I took her to the back of the dog park and sat with her on leash just watching her reaction to it. The second one was at night when usually no one comes in to the dog park and that dog got in to the holding area and then left. All the other times she's reacted to spaniels is when they have walked past the dog park. It's not like I just leave her to bark and growl and stuff and she has only started this the past week or so, so please don't make assumptions because you sound rude.
And to the person who says I need to "sort it out", that's why I posted this to see how I could "sort it out".
Thanks.