Hi, I keep racing pigeons in a pen in my garden and usually my pigeons are healthy. I have noticed a big blackish kind of ball growing on the pigeons stomach and neck, the one on the stomach is oozing blood and is big, I'm not sure of they are cysts or tumours and how to get rid of them, my dad used to say tie string round it to cut of the blood to it so it dies, is this true? Thanks! p.s live in the West Midlands