I posted some weeks ago when we first got Clive, a Patterdale, now 11 weeks old and his relationship with Buster, a Staffie, 8.  I'm pleased to report everything has gone fairly swimmingly and they are, as much as they can be at this early stage, friends!  A possible fly in the ointment, however, today Buster has gone to the vets to have a fatty lump removed, obviously because of the rough and tumble of play, they'll need to be kept apart ... just found out his stitches come out in 10 days.  My question is, is there anything I can do or not do to ensure the relationship is not ruined, if you like?  Will keeping them apart [pup will be in the kitchen] mean they have to rebuild once they come back together again?  Or am I over egging the pudding and they will be "fine" once Buster is fully repaired?  I just don't want to make any  mistakes ...

Would keep them together as much as possible, make sure that for the next 10 days you are able to spend most of your time with them and steer them away from rough play, when you are not available to supervise then you will have to cage one or the other, preferable both in different cages but leave them in the same room. With two feisty terriers it is important and this stage they are not separated or see you as offering special treatment to one of them. The pup may be sensitive to the others situation but I would not expect it at such a young age.

Do you have a crate that Buster could spend some time in when he needs to rest, but the pup can still be around him without bothering him. Also the pup could go in there when he needs a rest, and Buster can then pootle around without fear of having a puppy launching at him :-) BIG believer in crates I am! Plus the supervision as Gemini says.

Actually we have it the other way round, puppy has crate and we've then let Buster either rest in his bed or as he's up and about now, he can mooch around as he wants to, we've also bought a long lead for puppy when we're all together in the evening, that way not letting him "invade" Buster's space ... we'll then lead onto supervised play in a few days ... thanks for the advice here, much appreciated.