White Headed Pigeon with terrible breast condition

This isn't what you'd call a best photo.
This poor White Headed Pigeon had what I thought was a terrible disease. It is really sad to watch her turn regularly every day on her own because 6 other WHP's turn up together every day and I think they are shunning her.
So I took some of the photos of her condition to our local vet. She thought it wasn't a disease but was probably a cat attack injury.
We know that dreadful attacks occur on birds by the many thousands week in week out by marauding uncontrolled domestic and feral cats. But I am not so convinced that this is what has happened to this bird.
I couldn't debate this with the vet and I definitely wouldn't argue against the vets knowledge,but she hasn't seen the bird. She'd kindly stepped away from her surgery table for a minute to view the photos of this pigeon and ones of my little mate Shrikey. I'm concerned that Shrikey might have caught this same type of condition because I have just noticed a little patch of missing feathers around his throat under his beak. And some other wild birds have some patches that don't seem like injuries from fights.
What do think about this White Headed Pigeons condition,.,is it an attack injury or a serious skin disease.