I've noticed that I can hear my dog's claws on the ground when he's walking on hard floors or pavement, does this mean that they need trimmed? I've seen doggy nail clippers for sale in pet shops but is it better to go to a groomer? I trim our guinea pigs nails but with them I can see the pink bit at the top so it's easy to see where to avoid but the dog's nails are all black so I don't feel very confident about not hurting him!