I have tried hair ties, bracelets, ribbons, embroidery thread braided. Nail polish would not stay on the tiny nails.
What has worked for you to indicate who is who when your pups were whelped? I"m always afraid of anything tight on their little necks or string tends to fray and then their paws shread the makeshift collars into strings that entangle their little bodies. If you weren't keeping a close eye on them it would cause a serious problem.
