We're having a slightly miner issue. Trixie is very calm most of the time but every so often without warning she gets very hyper. This can be within 30 secs. She's playing with a toy and then suddenly (and I mean suddenly) she's off, running round the room/garden/house using doors/walls to stop and turn. At first we thought this was just where she got a bit excited (as it was only really happening while we were playing with her enthusiastically) but it seems to be getting worse. It’s happening 2/3 times a day and is sometimes when she's calmly playing with a toy. Now we don't really mind this but she's starting to get nippy when she does this. Again usually very calm but mouths as any puppy would. But when she's hyper she snaps (so far not bitten anyone) so thinking this could be a warning...? not sure what for though Anyway my question is... is there any way we can prevent her from getting this hyper? We don’t want to stop playing with her actively as this is her main energy release until she’s had her second vaccination but thinking that if we can prevent it, we could save her hurting herself or someone else.