Really pleased that the vets have now annotated his notes, so you can be reassured that nothing like this should happen again
I have lost count of the number of times I have almost said something and then either forgotten to say, or felt like it was fussing or whatever, only for it to become evident that if I had said what I intended, a subsequent problem would never have arisen - and I know I feel very angry with myself for the whole matter, so I hope you are being kind to yourself Elaine.
I don't know how many vets and vet nurses work at your practice, nor how substantial William's notes are, but these factors might go some way to explain why the team operating on him yesterday may have been unaware of the previous medical history
I am so sorry that this incident has happened to William, and I guess the cautionary tale for us all is never to assume that the person treating your pet knows everything about them and their- actually that applies in our own interactions with our doctors as well - not least because they are only human
Gentle hugs to William and I hope that Louis is being sensitive to his big brother's predicament.