I've learned to watch my nails to help me confirm some of the things I deal with - from small black lines in them, to pitting and the white lines that extend across the surface from the left to the right side of the nail.
If the white lines don't move as the nail grows out, it may mean that she's simply not getting enough protein in her diet, or her liver or kidneys may be struggling.
These articles may be of help to you:
www.livestrong.com/article/78232-reasons-white-lines-nails/emedicine.medscape.com/article/1106423-overview That is, unless she has closed them in some sort of door (cabinet door, car door) or some other sort of trauma.