Dog-dog play info video
I highly recommend consent testing during play, especially for pet parents (non dog trainers)
Short video on "calming signals"
Calming signals can be a healthy sign that a dog is regulating the excitement levels of their play/interactions. But if one dog is presenting calming signals and the other dog is continuously being overly rough, then that's where problems can arise.
Risk-averse methods of dog introductions and play
These are precautions I take to introduce dogs. Feel free to use all or some of these steps. These steps are great for helping dogs with issues with being over-excited OR fearful/shy.
Start out introducing the 2 dogs on neutral territory.
Start out at a distance with both dogs on leash, and practice having the dogs looking at the other and looking back at the handler for a food reward. (This method may be difficult with a dog who has little experience with distraction training.) Example: https://www.instagram.com/p/B7XDUm2hwed/
Go for a side-by-side walk together, without the dogs directly interacting, slowly decreasing the distance between the dogs. So maybe they start out across the street from one another, and then slowly one person is walking in the street. (This method is not good for a dog without training who would just get excited and frustrated. Nor is this a good idea for a dog who is very leash reactive.)
Have the dogs do SHORT greetings on leash where they get to briefly sniff the other dog and then return to the handler for treats. Keep the leash slack while the dogs sniff; pulling back on the dog can actually trigger aggression, as the physical restraint is frustrating. (This is not a good idea for a dog who is very leash reactive.) Example: https://www.instagram.com/p/B7Y0OGzhLyz/
During actual off-leash play, keep a leash dragging on both dogs, or maybe just the dog who tends to be overly rough/excited.
Implement frequent breaks where the dogs are separated and fed treats. Use leashes if necessary. Use space if necessary, as opposed to trying to make the dogs eat right next to each other while they're still excited.
Example of breaks during play: https://www.instagram.com/p/B7bdHT1hquK/
Practice recall and other bits of training during play!
Implement consent checks - see video above.
Related to consent checks: If one dog is moving away, trying to take water breaks and sniffing breaks, trying to hide - LET THEM. Don't let the other dog harass them while they try to calm down.
Arousal, rough play, etc.
A big factor of play (and dog-dog interactions in general) is AROUSAL. Arousal, or excitement, is neither inherently good or bad. If the dog is not aroused to some extent, it is not alive!
However, as arousal increases during play, different parts of the brain activate, and dogs are more likely to become defensive, predatory, rude, etc.
Signs of over-arousal during play depend on the individual but include: Increased vocalization, harder/longer gripping on skin, faster movement, clacking jaws, curled lips, and not taking micro-pauses or breaks during play.
Dogs take micro pauses and breaks during play to regulate excitement and ensure that feelings don’t get hurt. If they’re not regulating themselves, they need humans to help force them to take breaks and calm down. Over time, time-out policies often lead to dogs self-regulating more healthily.
Dogs who have relationships with one another might develop more intimate play, and that sometimes includes being able to participate in higher-arousal play without anyone's feelings getting hurt. This is because, as the dogs get to know each other, basically they figure out what they both like and don't like, and adjust accordingly!
I'm always happy to take a look at footage of dogs interacting and let you know what I think about it!