A friend has just had his 8 mth dog neutered yesterday and now the dog can't seem to control it's urination, is this usual? will things improve? or does he need to go back to the vets ASAP?

Hopefully it is just a result of the GA, if it continues I would return the pup to the vet as it could be an accident during the operation. Although incontinence is a known side effect of neutering I would not expect it to start so soon after the op.