Overgrown nails cause extension and lengthening of the toes and the dog's weight is shifted to the back of the foot. (neogreyhound.com)
Severely overgrown nails also need to be clipped off short and cauterized by your veterinarian under a mild anesthetic. (2ndchance.info)
For pets with arthritis, sometimes pain relief solves the problem of overgrown nails if it allows them to weight bear to an extent that the nails can be worn down naturally, or if it enables them to groom properly. (smallanimaltalk.com)