Use your left arm to keep the head on the table and use the left hand to hold the paw. It is easier to perform this procedure if you have a helper. See the section on restraining a dog for some additional suggestions. There are several styles of nail trimmers, including a guillotine type and a scissors type. The guillotine type is the easiest to use in dogs.
Long toenails can grow into the toe-pad.
This most often happens to dew claws, the claw on the inner side of the paw. Dew claws do not touch the ground so they are not worn down as the dog walks. The dew claw is attached to the leg by loose skin. The dew claw can usually be bent away from the leg so that you can fit a guillotine type trimmer over the the tip of the dew claw. Hold the trimmer in your right hand if you are right handed.