Could very well be the genetics SCG, maybe Murray birds are predisposed to it? Do you have birds from other sources? And do you have any problems with them?
I have birds from all kinds of sources. The turkey came from a friend who didn't have bumble in her flock so

That is odd... Isn't it? I have had a few cases of bumble, I thought mine all got red.![]()
The ones we have had here are not red. Just swollen with a blackish brown plug.
Is she limping?
Filth is good and why we have immune systems.
She limps a little bit, but not always noticeable even before I started treating her. She still gets on the highest roost I have and kerplunks down onto her feet every day. You'd think if they hurt that bad she'd try roosting lower or not at all.