I think dogs do this for various reasons. Depending on context, it can be "whew, glad that's over!" to "well, that was fun, what's next?". At any rate, not unusual, IMO.
Unfortunately we have the same problem with our boy (9) and girl (10). Off leash they play well - 95% of the time. The other 5% can be a disaster especially with small frightened dogs. My guys have gone after such animals and even bitten them - once drawing a small amount of blood. This behaviour seems quite instinctive and regrettably I have not been able to curb it. I do hope your pleasant little fellow doesn’t go this far. But we are talking about a very primitive breed.
