Acting possessive?

[shay19]

So I've had my 2 little sisters at my house since Saturday night, so we let them play with both dogs together as they have been acting really good around each other and the girls promised to watch them very closely the whole time they were together just in case Aida was still in heat (which I don't believe she is anymore becasue Bruiser has no interest in her other than wanting to play).

Well anyway, me and the girls were sititng on the couch last night and they were playing with Bruiser. He'd come up and lick their faces and just not stop lol. Aida was laying on my younest sister and started baring her teeth at Bruiser.... She's never done this before, ever! So imediately we all stopped playing like that and Bruiser layed down on the floor next to the couches and Aida curled up by me. I must have said something cause Bruiser came up to me and Aida again bared her teeth at him.

I've never seen her do this before and I don't get why she's starting now... I'm not sure if it's some kind of resource guarding thing or what??

I just don't want a fight to break out between them so any advice would be great.

[suziriot]

Definitely sounds like Aida is resource guarding against Bruiser. Put her on strict NILF (Nothing In Life is Free). She's still a pup, so it's not unusual to see changes in behavior as she matures. She's being a brat, and it's important to nip this in the bud ASAP. Here is a link to an article on NILF for puppies 6 months to 1 year. NILF is completely based on positive reinforcement, while giving your pup structure and boundaries.
www.terrificpets.com/articles/102212265.asp

[shay19]

Well that's exactly what I thought it was when I first seen it happen... we've already been working on NILF but we'll just get stricter with it. Thank you