Two of the first quilts I ever made were full twin size, one with warm and natural and the other a poly batting (don't remember the name). Their mother washes them every two weeks in an agitating machine. The quilts have had issues with the stitching coming loose (my machine then was not really made for quilting) and I have mended them, but there has been no problem with the batting on either. I've asked her to use only gentle cycle and that has helped, but the quilt tops are pretty worn. Better worn than put in the closet!
Front loading machines not only handle large items better than agitators but they are incredibly gentle. I really celebrated the day my old machine finally died and I got a front loader. All my clothes are doing better!
I really think that the combination of pets that may be very active and the constant washing are the culprits! Make your friend a wall hanging! Make her dogs each a quilt to be abused. She may be wonderful, but she is not a "quilt" person.