This concept of cocker rage is an interesting one, from what I can see there are different ideas about it and I'm intrigued by the idea that it might exist as a kind of stand alone neurological disorder/ epilepsy with no environmental trigger (no matter how disproportionate the response appears to be). How would that even work in practice, considering the aggression is directed to someone, or some animal - I can't imagine you would have a dog diagnosed with cocker rage that throws a display with no target, and hence no situational trigger.
When you hear people's stories surrounding it and tease out what is happening there is normally a situation - it does not need to be consistent, it might only happen once in every 20 occasions the person thinks is identical to ones that happened before when no aggression was exhibited, and then I tend to think that other subtle factors are all at work to put that dog, at that time, over their threshold. Tiredness, resource value, hangover of earlier stress in the day unrecognised by owner..all conspiring to edge over the threshold.
And if there is then a trigger and a threshold, albeit hard to fully comprehend due to our deficiencies as owners recognising the psychology of our dogs, maybe it is something after that that marks out the response as unusual and quantified as 'rage' by some - the disproportionate response - the extent of aggression and duration of aggression? Sorry, think I am sidetracking from this thread but I am intrigued by the 'rage' concept, as an owner of a dog who has had apparently unpredictable, disproportionate and prolonged response that I have never witnessed or heard of in another dog before getting him.