an EKG, heartworm test, chest radiographs and possible echocardiogram are in order. and in that order
dr mark

Excepting heartworm unless the dog has travelled to an endemic area?....AFAIK, no clinical cases yet in UK from UK transmission.

Thanks for the info, but the heart has been ruled out as a problem now - it's more to do with the dogs being sensitive to the anaesthetic (it's rumoured that BC's were used in the Springer to increase trainability many moons ago, so it's possible that their sensitivity to anaesthetic may be a relating factor).
Well I suppose that's one less thing to worry about!

I'll be speaking to my breeder tomorrow night, but he's assured me it's just something to be extra careful about and that's it's best to let the vet know, which I will do tomorrow.

Thanks again everyone.