Sudden possessiveness of owner
Just have a question I'm hoping someone can help me out with.
I have 4 dogs in my home, 2 gsds (males), 1 jack russell (female) and a gsd/newfoundland mix (male and also the youngest).
Within the last few weeks the gsd mix has started growling and barking at the other dogs when they try to come near me but only when I'm sitting down on a chair in my back garden or lying on my bed when one the other dogs comes over for a rub, he has snapped at one of my other gsds leading in a small cut on the other dogs nose (he's the last member of the pack and he is also one years old). The only thing that has changed within the last few weeks for him is I have a friend who usually comes and plays with them all but he does show extra attention to the gsd mix, I'm wondering is this behaviour due to the absence of this person (they do play a bit rough also I don't know if that's important). Everything else about his routine is the same other than this he is an extremely laid back dog that is always happy so I'm not sure why now he sometimes gets aggressive when the other dogs try to come near me. When he acts like this he seams to try stand taller all the hair on his back stands up but he is still wagging his tail?
Any tips on how I can stop/prevent this?
Hachi (GSD) - Age 2 - At the bridge
Roku (GSD) - Age 4
Maverick (GSD) - Age 2
Missy (JRT) - Age 4
Koda (GSD/Newfoundland mix) - Age 1