What Janome are you referring to? Feed dogs don't cause skipped stitches. The wrong needle match to your thread can. Try a 90/14 top stitch...that may fix your problem. I have seven Janome machines ..love them all....partial to my 6600 and 8900. The all work best with the 90/14 topstitch needle when quilting.....please post your model number...perhaps we can help more...there are numerous "horizon" models in the Janome line.