I had problems like yours and a breeders like yours from Florida. Didn't care that they were breaking peoples hearts by breeding unhealthy stock, I had two dogs from them that had heart problems and they weren't related! Just remember that Bentley doesn't really realize he's sick and will carry on as best he can. They are so stoic and brave. He is lucky to have such a wonderful family.
God bless,
Nano
God bless,
Nano
