They will usally get more aggressive if it depends on it. they get more aggressive when getting older but as a puppy its just play nothing else, if the mom is still around by then...she will teach the puppy by barking or growling but the mom shouldn't be in the picture at more then 8-9 weeks unless it was your dog that had the puppy and you planned to keep one of the puppys from the litter!
this is puppy play and is very good social skill learner..people pay lots of money to put their puppies in puppy kindergarden classes...as long as they are both having fun let the kids play...
I am a dog trainer and I get asked the question regarding rough play and aggression a lot. The rough play between the dogs is natural, but keep an eye on them and be ready to intervene when you feel that the play has escalated into the danger zone. Dogs that have been well-socialized with their litter mates (kept with litter mates until at least 7 weeks) will have learned bite inhibition and most canine communication signals. Watch your dogs when they play: If one sends a signal that it's too much (i.e. a yelp) does the other one back off a bit and wait for the other to return to play? Educate yourself about other canine communication signals and watch for them. For example, if they are both making a lot of growly noises but are still using the play bow, then things should be okay. Be sure to watch in case one gets cornered. They may feel threatened and strike in fear.
You need to be the pack leader and decide when things have escalated beyond your comfort zone and then give them both a time out. You make the house rules and you have to make sure everyone abides by them.
As for rough play between humans and dogs, I don't recommend it except with some rules: 1) not with children -- ever! 2) the game ends immediately when the dog is too rough. 3) rough play with a toy and continue when the dog returns the toy to continue the game; the human should never chase the dog for the toy. This way the human is in the dominant role of leader, and the dog can play if he/she follows the rules.
They're having fun with each other. This type of play (between puppies) will not promote aggression,
For human interaction, I would recommend you stick with tug toys. Puppies love a little rough housing, and that's okay, but any kind of aggression should be nipped in the bud.
When they're tuckered out they'll have their cuddly moments, but right now it seems like their "too busy" for cuddling right now. =)
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