Another source of udder problems?

I am writing about “A Problem Only Mares Can Have” (Consultants, EQUUS 490). I used to have a problem with my mare getting lots of debris and sheets of stuff between her teats. I picked it out by hand once a week. Thank goodness she enjoyed me doing it.

I had blamed it on her being turned out on pasture 24/7 and collecting dirt. After she grass foundered, I changed her management so she lost a lot of weight, and now the problem has all but gone away. She is still on 24/7 turnout but on a dry lot. I regularly check her udder out of habit but rarely find anything significant. Tracy Meyers Pennsburg, Pennsylvania