“Because he is lazy” is probably not the answer as to why your dog drags his back feet. The sound of scuffing or dragging of the hind feet is less noticeable on soft surfaces such as carpet or grass. Walking on tile, wood or other smooth surfaces often produces an audible “click” as the foot is pulled forward. Walking on rough and hard surfaces such as cement or asphalt is more likely to produce a scraping sound. No matter the surface, close observation may show that your dog is not picking up one or both feet.
“Clicking sound may be heard on hard surfaces”
If you suspect this is happening, take a close look at the edges of the nails on his two middle toes; signs of wear means this problem has been going on for quite a while.
In my practice, the most common reason for this to occur is from the pain of osteoarthritis (OA). Your dog will move in ways to minimize the discomfort of OA as he moves forward. One way he minimizes pain is to avoid lifting the foot very high from the ground. Dragging the back feet can be a result of this motion. Lifting the leg causes some compression on the arthritic joint as the muscles contract, exacerbating the arthritis pain. It is much easier (and less painful) to slightly drag the foot when walking.
Another common reason for this is any neurological issue. Two examples are loss of sensation or perhaps the loss of something called “conscious proprioception.” Conscious proprioception allows you to know where your extremities are without looking at them. It is often an early warning sign of a neurological problem. Sometimes this can occur at the same time that there is also pain. For example, in a condition called Cauda Equina Syndrome which has both a pain and neurologic component. This syndrome causes an impingement, or pinch, on the spinal cord at its termination near the pelvis.
Look for someone that is an expert in pain management if your dog has this problem and make an appointment for an examination. Early intervention, in both of the above examples, not only makes your dog feel better sooner, but can open up more treatment options.