These are listings of doctors who are in network (= covered by a certain insurance provider), but the reality is these listings are fake, as in no longer correct. Insurance companies keep these listings anyway to create an illusion of choice (aka, I am a good insurer and I have a lot of providers, that are contracted with me, for you to choose from).
People who discover that most of these doctors are unavailable, are effectively denied care or have to resort to out of network doctors that are covered at much lower rate or not covered at all (= higher out of pocket expenses).
I’m so sorry and hugs to you, and thank you for sharing his story. Please hang in there and if Bear needs to go he knows he was always loved and cared for. Kiss your fur baby for me.