Dom has always suffered from dry & irritated skin since we adopted him as a stray almost 2 years ago. I havetaken him to the vet about it acouple of times, but they couldn't find anything obvious and suggested a possible food intolerance. The irritated skin on his neck improved a lot over time, but he still had dry patches ofskin on his back at time. Last week, his back felt quite scabby. I normally brush him with a ball-pin slicker to try to get undercoat out. A few days ago, I used a zoom groom, which got out loads of undercoat, but also seems to have stripped him bald on his back. I wonder if it is because he is too big to groom his back. Obviously I will take him to the vet if there is no improvement. The odd thing is, it doesn't seem to botherhim, although when I brush him, it can be sensitive at times. For the most part, he loves me brushing his back and I have to give in after 15 - 20 minutes and sometimes get a whack for daring to stop!
To give an idea, the patch on his back is about 5 inches long.
http://imgur.com/a/UgFtB
PS - a flea allergy crossed my mind. I have been a bit lax with Kylie being ill and losing her, but I gave him an advocate on Thursday (the previous time was about 8 weeks before then)