She has some sort of dermatological condition that makes her nails either too soft or too brittle, so they split. If you find a split before it reaches the quick I would seal it up carefully with superglue (read the instructions!).
If it has reached the quick you need to take antiseptic precautions and protect the foot while the nail heals, possibly with bootees. Try supplementing her diet with sources of collagen (e.g. Gelatine) and zinc, which is supposed to be good for strengthening nails.
Bootees are easy to make: Choose a strong material like canvas, and draw 2 C shapes that are larger than her foot all round by about an inch, and have a long enough "neck" to reach her wrist/hock. Stitch them together so you have a "sock" when you turn it inside out. You can either sew velcro to it as a fastening, or just tape it on. Do not use elastic as this can damage the circulation of blood.
If it has reached the quick you need to take antiseptic precautions and protect the foot while the nail heals, possibly with bootees. Try supplementing her diet with sources of collagen (e.g. Gelatine) and zinc, which is supposed to be good for strengthening nails.
Bootees are easy to make: Choose a strong material like canvas, and draw 2 C shapes that are larger than her foot all round by about an inch, and have a long enough "neck" to reach her wrist/hock. Stitch them together so you have a "sock" when you turn it inside out. You can either sew velcro to it as a fastening, or just tape it on. Do not use elastic as this can damage the circulation of blood.
