For those who have older or less active dogs and don't get their nails trimmed/dremeled on a regular basis. Notice on the longer nail how it is physically pushing the toe up or even causing the toe to twist? This affects the joints and can be painful if a nail breaks! It is recommended that parents do monthly visits to maintain a proper length, and more often than that to help them recede each time. If you hear clicking, it's time to get those nails trimmed. Some dogs have naturally long nails and finding the "quick" or nerve can be difficult, especially of the nails are black. There are ways to see how far nails can be trimmed as some have a crease on the underside of the nail allowing the nerve to be seen. There are black, brown and white nails. Even white nails can be difficult to safely find the nerve.
So when in doubt have a professional trim/dremel them, whether it's a Veterinarian or a Groomer. We are used to being the bad guys and allowing parents to "save" their healthier and happier pups.