He may well see you partner as a threat, men are percieved by dogs as more threatening on the whole because they are usually taller and have deeper voices than women, Is he submissive aropund your partner, rolling on his back or lifting his back leg ? Often when people tell the dog off, they continue to keep threat on after the dog has stopped doing whatever they were supposed to, if the dog still feels it is under threat, it may well use aggression to rid itself of the percieved threat.

Rage symdrome (idiopathic aggression) is quite rare in dogs, but the other posters are correct it does appear in cockers, especially solid colours. The aggression does take place for no known reason, and is usually at a family member.

You need to keep a diary of these aggressive outbursts, what lead up to them and see if you can see a pattern forming.

Thank You Jenny

I think he does feel threatened. My partner is a butch 6'4 and even his simple 'sit' command can sound intimidating without him meaning it to be!

I will keep a diary, it is strange how it's always the same time of day the behaviour occurs.

I'm also going to make an appointment to see the vet and see what he suggests!

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Cocker Spaniel Breed Council/Temperament & Training
read this and see if helps towards identifying - was he on JWB puppy food as well ?? and in the evenings is it gloomy in the room when OH comes home ?

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Thank you. Yes he was on JWB puppy food. The vet recommended it to us. Sorry, who do you mean by OH?

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OH - other half (boyfriend/hubby girlfreind/wife)

I have days like that too Gemma