Lost a LGD...questions

[SMaxwell]

It sounds like all the classic signs of heart failure. And that can strike at any age. Had that happen to a perfectly healthy (or so I thought)6 year old Border Collie about 11 years ago. And with a 2 year old Akita back in the 80's. Both times it was determined to be a heart attack.

I wondered that also and the vet said that his heart sounded really good and strong, even when he examined him a few days earlier. In fact, I think he said it sounded good even a few minutes before it slowed down and stopped when we took him in last night. I don't know enough to know if there could be issues that the vet could not pick up on just listening. Are Pyrenees or Anatolians prone to heart issues?
Thanks