Shining the LED light through the nail should show you where the quick is, even on black nails.If you are still unsure about a black-nailed dog, only cut a tiny sliver off and examine the area you cut underneath. You should see a whitish-gray area. You can cut another tiny sliver off, as this is still a dead nail. Keep cutting slivers no more than 1/16th of an inch at a time until you see a black spot in the center of the nail. This is the pulp, which means you can’t cut further.The process for white nails is much simpler. If you hold your dog’s nail up gently, you should see a clear transparent hard nail and a pinkish-solid section inside. The pink inside the nail is the quick, and this is the part you must not cut!