A week ago my partner surprised me with a 8 week old springer spaniel which ive wanted for years. We also have a 10 year old staffie who up to now has been great with her showed no aggression at all. Yesterday daisy my 10 year old got out the house and ran across the road and attacked a Jack Russel one of our neighbours I didn't see weather the other dog had showed any aggression before. It needed stitches which I will be paying for. I am so upset and now really worried for the pup. Daisy hasn't really taken much notice of the pup she's laid near her had to tell her a couple of times and tried to play but staffies play ruff so the pup has ran away. I'm doing everything right but now concerned daisy could just turn. Any advice would be appreciated

First given what happened yesterday your old girl will need time to calm down and return to her normal.state.it may not be obvious but she is likely still to be a bit excited and on and more easily aroused . As for pup I would supervise at all.times,not just because of yesterday but it's always wise when u have a new phone and other dogs
. I would.use baby gates so they can be separated and give daisy peace and quiet. Pups can be very full on and although she may be tolerant u need to give her own time and space.
I am sure others will have suggestions too

Thank you so much for taking the time to reply. We have a stair gate which keeps the pup in the kitchen as daisy chills a lot in the room. I suppose time will tell 1 week in and everything's been great yesterday just through me and has sent me into a panic which I know isn't good for daisy either

Just make sure daisy gets time to become calmer again .things like that cause a great increase in adrenaline and it takes time to disapate.she may also be better just staying at home without a walk today . Take her interactions with pup calmly and slowly with u to watch .I would be doing this in any case. her response yesterday could.have been for any number of reasons and won't be redirected to the pup buy good to be vigilant