well you have to tell your self why the dog has long nail at the 1st place... does she/he live indoor?:uh-huh:
well you can pick them up at the vet or pet shop... ask for nail clipper depends on dog's size. only cost you $10~20 max.
I have clipper will does the job...(for humans) but also will work on k9.
if you take to vet; will cost you more than the clipper hahah...
black nails... hhhmmmm it's hard to see the blood vessels on that