Nippy behaviour...

My first memory of a Spaniel was from when I was about 7. I went with my mum to a volleyball tournament and one of the ladies playing had a Spaniel. My first thoughts were naturally 'aah cutest dog I've ever seen, lets cuddle', but I was very quickly warned not to try and interact with the dog - where it was lying half on top of the owner's handbag(did I sense protection mode there?) - as she doesn't like strangers... So naturally when I met Henry, our neighbor's Cocker Spaniel and Salvador's best friend, I was amazed at how sociable and easy going he is - long story short, I got young Salvador.

Henry (Salvador's bestie)

 Aggression and biting first came up again when my boyfriend told me about a rescue Spaniel they had as children. To be fair, this dog apparently went through quite a tough time before they rescued her and she seemed to take a liking to girls and would therefor 'protect' his mum and sister by growling whenever anyone came near the couch.
Another account is an aunt's dog that fiercely 'protected' her whenever they were in the bedroom. All the other accounts come from when we've taken Salvador to the Saturday Market on many occasions. People are generally overwhelmed by his cuteness and friendliness, before the childhood accounts of a mean Spaniel somewhere in the family comes out...
I would kind of shrug these stories off and think that Salvador is way too sociable and used to others - large and small, for him to ever become a biter!

BUT I seemed to have been wrong!

About 3 months ago I was lying in bed, half asleep with Salvador on the floor beside me and my boyfriend came in after working late at which Salvador promptly jumped up in an unfriendly manner, as if to bite... When I heard of this I thought perhaps he got a fright, yet a few minutes later the same thing happened (and I witnessed it this time!).

Now, I've gone through the trouble for you and read up on Spaniel behavior and there are countless sources explaining that Spaniels are quite POSSESSIVE dogs. Many see this as a bad thing although this is often because we usually don't like to punish our pets and insist on treating them like kids. DO NOT DO THIS WITH YOUR SPANIEL!!!
As soon as Salvador attempted that second little attack he was banished from the bedroom! If he can't share the room with others then he can't be in it - as simple as that. When you tolerate this kind of behaviour for the sake of thinking it's cute that your dog is being protective over you, you are setting yourself and your dog up for a world of trouble.
Set boundaries and stick to them calmly and consistantly - this is the only way to avoid naughty behaviour and future problems.