We have been dosing daily with panacur, and I was able to tell him that Joop seems to have improved: he hasn't lost any more weight (or not obviously so), he's eating well, and is becoming difficult to catch to give his medication!
So, e.cuniculi fairly serious, but there is a treatment and it's manageable. so things could be worse.
From what he said, the abcess is pretty tiny and not particularly aggressive compared to a lot of the ones they see. (Total contrast to what our normal vet said, and well worth the consultation and test fees - our vet didn't notice the e. cuniculi problem at all and thought the abcess would probably finish him off fairly quickly)
He doesn't think it's worth operating on it at least until we are sure the e.cuniculi is well under control, but he also doesn't see any problem with Joop living with it on a fairly longterm basis. He thinks we'll be lucky if it clears up entirely, but that with antibiotics and painkillers, it may not cause him major problems.
On the whole I'm feeling quite positive about this, though I am going to have to come up with some solution for if we go away, because at the moment Joop needs twice-daily medication, which is rather a lot to ask of a petsitter or relative. Hum.
I need to start weighing them to make sure their body weight is being maintained. They are too little to register on the bathroom scales, and too big for the kitchen ones. Hum2