Either that, or he scraped it on something. If it is not bleeding, I would not worry too much. Cats are resilient!

Onyx and Abby started having mysterious scabs and scrapes all over their backs, back in October. It went on for more than a month and I wasted money at the vet trying to figure out what it was. They ruled out fleas and allergies, and I did not see any play-biting or fighting going on. I finally put two and two together and figured out they were scraping their backs under my bed. I had put bed risers on to raise it slightly, and that seemed to make them walk differently under the bed and scrape themselves on the metal frame. We wrapped the frame in padding and presto, the ugly scabs and scrapes went away. I am assuming this is NOT an issue (your bed), but it's possible Brodie scraped it or got into a fight, and there is really not a heck of a lot the vet will do other than to put on an ointment to soften it up..

Brodie'll be fine !!