I have a brother and sister, same litter, 2 yrs old. His nails need clipping once every two months, hers minimum every two weeks. His are perfect show dog trim, no resistance at all. Hers are long, she is resistance, and i cant get them anywhere near as short as his without nicking the quick. They both are great lovers of philly cheese and ir makes it much easier for us to smear some where she can reach without squirming. He just sits and lets me do it. Been doing this for 30 yrs. but i have never seen nails grow as quickly as hers. I have been told the difference is hormones...?