Here is how I do it.
First, I start with the dog ON a grooming table and securely noosed. It's much better if you have a helper.
Standing at the head of the dog, show the dremel, let her sniff it, and immediately treat. These treats should be something especially yummy such as tiny cheese squares, or small pieces of cooked chicken, beef, or liver. Something REALLY yummy.
As soon as she sniffs or touches the dremel with her nose, treat, and say GOOD.
Next, pick up one front paw, touch the dremel to the foot, and treat. It does not have to be a long touch. Just pick up, touch, treat. Do each foot the same way, and take the dog off the table. Reward again.
Do this each day, twice if possible, until you can handle each foot and touch it with the dremel not running. Each touch with the dremel means a treat. When the dog is comfy with all this, and not until, go to step 2.
Step 2, let the dog sniff the dremel. give a MOUTHFUL of treats. Step back, turn ON the dremel, treat some more.
Touch each foot and treat while you hold the dremel in your OTHER hand. Do this until the dog ignores the running dremel.
Next, touch the dremel to the foot, while it's running, but not with the sanding barrel, just the body of the dremel. touch, treat. touch, treat. Ignore any struggles, etc. Touch and treat until you can touch with the dremel running with no problem.
Contineu with this desensitizing treatment until you can touch each toenail with the dremel.
You must be CAREFUL with a dremel. You can get a very nice nail, but they heat up FAST, you may only make 2 SHORT passes on a nail before you must go ot the next one so that the nail does not get too hot. This is very painful if it happens and can undo all your good work.
While I"m doing this desensitizatio
n therapy, I do not console the dog if it misbehaves. I speak firmly, and I tolerate no growling, snapping, grabbing, etc. This is one reason I keep the dog noosed, because some dogs WILL bite during nail trimming.
This is another EXCELLENT REASON to teach body handling when puppies are very young.