Thanks for all the information.
Just got a new sheepdog called Molly the Collie.
She was already 6 months old when I got her and had been living in a field. Therefore, her pads were soft and her claws were long. I have been walking Molly the Collie on hard ground so she can naturally wear her claws down and toughen up her pads. It worked for my last collie. I had my last Collie, Maud, for 18 years and never once had to cut her claws.
However, with regards to Molly the Collie, my concern is that her dew claws on the rear legs are long. I know I can just take her to the vet, but I would rather not.
Any advice, greatly appreciated.