There are some breeds with inherited kidney failure which causes them to die very younf eg west highland terriers and cocker spaniels and others. The operation may have just accelerated things if this is the case. Surgical mistakes, notably a ligature encircling one or both ureters (the tube from the kidneys to the bladder) have also been recorded. An ultrasound may diagnose the latter in which case it should be corrected urgently but you will need a specialist surgeon to do this. The anaesthetic may have caused a problem but this is unlikely to be enough of itself.