We might pamper our little Butterflies, but Papillons, Phalenes are a quite active breed of dogs, and injuries-, broken toenails are common.
Injured nails can be very painful and can cause severe foot pain, and limping. The dog's nail bed has, as humans have, many nerves, and therefor is very sensitive.
A broken-, or torn nail can also lead to an infection.
I recently posted an article about nail care for our Papillons.
http://www.roadsend-papillons-phalenes.com/2013/04/papillon-phalene-dog-toenail-care.html
Papillon, and other small dogs, lap dogs, are kept often in homes to the most part,and their nails are too long.
As longer the nails are as more prone they become to torn, or injured nails.
Prevention:
Keep the nails trimmed regularly, and short.
Resources:
http://www.ehow.com/list_7231194_dog-toenail-injuries.html
http://www.vetinfo.com/dog-nail-injury-treatment.html#b