I have friends who have just got an adorable 6 month old black spaniel cross from rescue, and was concerned to hear he had attacked them without warning when a bone he had been given was removed. I am heartily hoping it is a dominance issue over food but was concerned by the severity of the attack and the description of his eyes going blue ( they are brown) and him seeming a bit dazed when he finally calmed down, after they had prevented him getting at them any more.
I researched spaniel rage on the Internet and was struck by some similarities with descriptions of true spaniel Rage syndrome, which apparently is rare but a real condition, and my personal experience in a specail school. I had a lovely lad, normally of sweet temperament, who could not be around any dangling chords - unfortunately no one told me until I came to work wearing a crochet jacket with long tie cords at the neck. As he flew at me out of the blue and grabbed the cords so tight he was strangling me, the look in his eyes was pure fear, not aggression at all. He was eventually MRI scanned and diagnosed with temporal lobe epilepsy. With appropriate medication his strange fits, for that is what they were, ceased.
I read temporal lobe epilepsy is one suspect in causes of Rage syndrome, and as Impulse control is in the temporal lobe, it seems reasonable any epilepsy in that area might cause instant rages, triggered by whatever stress was also present.
I would be very interested to hear how this spaniel's situation has progressed, and just hope my friends pup, which I mind during the day, has behavioural rather than medical issues. So far it has been an isolated incident, not witnessed by me.