girth sores

[GoldenCMK@aol.com]

My husband has been riding his mare for a year now in LD and he just started 
doing 50 milers. They have done 2 so far but on both rides the mare has 
swelling caused by the girth right behind elbow area after the ride. This 
mare rubs easily and have had to use a fleeced lined girth to keep her from 
getting sores. The mare has a deep heart girth so the girth tends to slide 
forward during the ride. Does anyone have a suggestion? Or had a similar 
problem?

Maria