
I've removed them myself on guinea pigs, but never had the nerve to do it on a pup for some silly reason. I have them done around 48 hours old, and hold them myself for the vet.
I'm talking pups that weigh 3 or 4 ounces on average. You can imagine how little room there is, with me holding a miniscule paw, while the vet removes the dew claw. I get charged a basic consult fee for a litter, whether that be 1 pup or 5.
Many years ago with a Toy Poodle litter, the breeder of my bitch removed the pups dew claws. They grew back! My vet has never, ever left anything in, and uses a caustic pencil for blood flow. As do I if I am cutting nails and go too far.