Nails and pet biomechanics
Keeping your dogs nails trimmed is essential for good posture and movement in dogs. In many medium to larger breed dogs this isn't too much of an issue in younger years when they are quite active and wearing their nails. It often becomes more of an issue as dogs age. Smaller dogs that don't have a lot of weight to wear nails as they walk can have issues from puppyhood.
When the nails are too long they contact the ground whilst your dog is in a standing position. This changes the position of the toe to accommodate the nail. This may mean that the toe is more bunched up - putting more pull on the flexor tendons at the back of the legs. Alternatively that the toe is offset to the side. This will affect the balance throughout the leg and whole torso. For example in the outside toe on a front leg is deviated out to the outside, that puts more pressure of the inside of the wrist, elbow, shoulder and neck. To compensate for the change in balance in the neck the opposite back leg will take more of the strain - creating strain patterns in the lumbars, sacral joints and may go all the way to the back toes. It is all connected, and it will all compensate, so you can see the need for maintaining properly clipped nails.
When nails aren't getting worn down properly the 'quick' - the part of the nail with the blood vessel and nerve in it, starts to grow longer. This can be really problematic for older dogs who may have other issues such as arthritis contributing to mobility problems. With long nails, the mobility issues can be compounded, as well as contribute to loss of grip when walking. The good news is the quick can actually recede if the nails are clipped short then regularly maintained with filing or grinding. This will all improve posture and allow better mobility in our oldies.
Whilst thinking about nail health is often left to older age when it becomes problematic, training dogs at younger age to calmly accept handling and touching of feet will make life much easier. Teaching your pups to accept their feet being touched, giving them lots of praise and treats whilst doing it, is a great investment into the long term health and mobility of your dog.