This section is from the book "The Dogs Of Great Britain, America, And Other Countries. Their Breeding, Training, and Management in Health and Disease", by John Henry Walsh (Stonehenge). Also available from Amazon: The Dogs Of Great Britain, America And Other Countries.
Before weaning, any cropping which is intended, whether of the dew-claw or tail, should be practised, but the ears should be left alone until the third or fourth month, as they are not sufficiently developed before. If, however, the operator does not understand his business thoroughly, it is better to leave the latter organs alone, until a later period, as otherwise the proper quantity may not be cropped or rounded, as the case may be. Indeed, ever the most skillful hand will hardly ever manage either the one or the other well before the fifth month; and in hounds it is usual to defer it until they are nearly full grown, as they often lose a considerable quantity of blood, which interferes with their growth. But the tall and dew-claws may always be best done, and with least pain, while with the dam; besides which, her tongue serves to heal the wound better than that of the young puppy, who has hardly learned to use it Regular dog-fanciers bite off the tail, but a pair of scissors answers equally well; and the same may be said of the dew-claw. If, however, the nail only is to be removed, which always ought to be done, the teeth serve the purpose of a pair of nippers, and by their aid it may be drawn out, leaving the claw itself attached, but rendered less liable to injury, from having lost the part likely to catch hold of any projecting body.