Spiked Pink Designer Leather Dog CollarSpiked Pink Designer Leather Dog Collar SIZING INFO; If your dog has an 18" neck and is full grown, we suggest a 16" 20" collar for a perfect fit. (We don't go by the total length of the collar) If your dog has an 18" neck and is still growing, 18" 22" is the best size collar to choose. If you do not have a tape measurement, use a ribbon or a shoe lace to wrap around your dog's neck. Mark where the two fingers meet and measure against a ruler. ***Our