How long for a cracked / bruised rib to heal? Discussion in 'Health and wellbeing' started by rustybug, Sep 15, 2012. Nearly 3 weeks ago I was knocked over very hard by a heavy dog running fast. My feet left the ground and I came down on the top left quarter of my back. I felt like I'd possibly cracked or bruised a rib - it hurt like crazy to breathe deeply, and sneezing made me actually almost cry.