The grinders are quite effective, though many people use a Dremel, finding it more robust. But whatever you use you will need to condition your dog, get it use to it. Personally I've always used clippers. This was a little piece I wrote on the subject a while back.
Firstly a little about the clippers. Labradors are not exactly a small dog so don’t go bothering about small clippers, and be prepared to pay a bit for them. Cheap clippers blunt quickly, lose their edge so tend to pinch the quick rather than cut nicely. I prefer the scissor type rather than the guillotine type and to me there are only two makes worth buying. Either Millers Forge or Mars. Both are made from good quality steel and will hold a nice sharp edge for years. I would also get a styptic pencil, the kind men use to stop bleeding when they cut themselves shaving. (Everyone, however careful, has at some time nicked the quick and believe me, they really bleed!)
Spend a little time preparing your dog, getting him/her use to having his paws held without struggling. I start by just touching the paws, and if and when thats accepted without a struggle I move on to holding the paw. Many dogs don’t like having their paws held, so don’t rush it, build confidence. The next stage is to hold a toe rather than the whole paw. Remember there is no rush so don’t move from one stage to the next until the previous stage is really sorted. The last stage is to hold the toe in one hand while holding the clippers in the other, and gently touching the clippers on the dog’s toe. Once you have progressed that far it’s time to start claw cutting!
While holding the toe, look at the claw. It’s like an inverted U with the quick running down the middle. Think about that for a moment. If you place the cutting edges of the clippers either side of the U the pressure will squeeze the sides of the claw onto the quick, pinching it. This is going to be very painful and will put the dog off having his claws clipped!! Always place the cutting edges on the top and bottom of the claw so it does not crush the sides in onto the quick.
So, the day has arrived! Get everything ready before you even think about starting. Then. Dont rush, but also don’t faf around. Take a toe and clip it! As quick as that. Dont try to take much off at this stage, just tip it. At this stage again it’s about building up confidence. One toe is enough for the first time. Probably later in the day do a second toe. Remember, it matters not if it takes two weeks, a toe a day to begin with. It’s not a race. It’s about not frightening him, and about him accepting that it’s going to happen.
I said initially to only tip the claws. Some dogs have semi transparent claws, where the quick is easy to see as a pink area just back from the end. As the claw grows so the quick tends to grow with it, so you cant cut back maybe as far as you would like. But by cutting back little bit at a time the action of the dog walking causes the quick to recede further up the claw, allowing you to cut it back a little further each time. Some dogs have black claws, which make it much harder, because you cannot see the quick. With these it’s a matter of being careful, trimming back just a little at a time until you can see where the quick is.
Trimming claws is not difficult providing you follow the desensitising procedure at the top of this post, and easily something any dog owner can do.