Her udder is normal, as is the crusty stuff. She just needs to have her teats cleaned, you can use Excalibur, the same stuff you use on a stallion or gelding when cleaning their parts. I take a bucket of warm water, a roll of paper towel and the Excalibur out when I'm grooming. I put the Excalibur in my hand to warm it, and then rub it all over the mare's teats. I groom her for 10-15 mins, then rinse with the warm water. I dip clean paper towel in the water, rinse the udder and throw the towel away. I get more clean paper towel and rinse and clean off the gunk until the towel comes away clean and there's no soapy residue. Be careful and make sure she's appreciating the attention, some mares can be pretty testy about getting cleaned at first, until they realize that it gets all that itchy stuff out of there.