Long, unkempt nails not only look unattractive, but over time they can do serious damage to your dog (not to mention your floors). When nails are so long that they constantly touch the ground, they exert force back into the nail bed, creating pain for the dog (imagine wearing a too-tight shoe) and pressure on the toe joint. Long term, this can actually realign the joints of the foreleg and make the foot looked flattened and splayed.
Again, this isn’t just an aesthetic problem, it’s a functional one: Compromising your dog’s weight distribution and natural alignment can leave her more susceptible to injuries, and make walking and running difficult and painful. This is especially important in older dogs, whose posture can be dramatically improved by cutting back neglected nails.
In extreme cases, overgrown nails can curve and grow into the pad of the foot. But even if they are not that out of control, long nails can get torn or split, which is very painful and, depending on severity, may need to be treated by a veterinarian.
And in the end, unattended nails create a vicious cycle: Because the extra-long nails make any contact with his paws painful for the dog, he avoids having them touched, which leads to unpleasant nail-cutting sessions, which makes both human and dog avoid them, which leads to longer intervals between trims, which leads to more pain …