My Finnish Spitz

Question
I adopted a Finnish Spitz a while ago and have been training him since day one. He's usually very well behaved and listens to me without hestitation. I also own a Chihuahua (also well behaved but shy). He plays with her and my friend's dogs (which consists of another Chihuahua and a Dalmatian/Pittbull cross). He's very gentle with all of them and usually treats them as though they were his puppies.
Recently, my housing partner adopted two Lab puppies and we decided to introduce them so that He could get use to them before they got older. Initial response was promising and he even let them sleep with him. He temperment toward them has changed lately.
When the puppies try to play with him he growls at them  and he won't let them eat with him anymore. During the last feeding I kept him and the puppies seperate but when he finished he snapped at one of the puppies as it was going by. I've also noted that he becomes agitated when the puppies are around the Dal/Pitt cross and growls at them.
Do you know what could be causing this behavior change?
What can I do to fix it?

Answer
Hi Helen, You are simply experiencing a disruption in the pack order. When he snips or growls at the pups, you (as his pack leader) must snip at him and tell him no. You can do this without harming him by giving him a quick pinch to the skin on his neck, preferably underside. Give him some power, by letting him eat first, but then supervise and allow the pups to eat with him. If he gets angry, set limits and make him "Share". Don't allow him to be protective of toys, food, other dogs, you or anything else. Make it clear to him that the humans in his life are his pack leaders and you have it in control, so he does not have to overpower the pups. This should help to bring the pack back into order. Leave me some feedback, a nomination (if you wish), and please keep me posted on how things go for you. Thank you for writing. Regards, Susan