The Root of the Behavior
Though our dogs have been long domesticated, we still see this ancient and deeply ingrained instinct in them today. Dogs intuitively understand that the one who holds the resources is the one who also wields the power. In your home, that person is you. Your dog understands this. Though equipped with sharp teeth, powerful jaws, and physical strength, which channeled inappropriately could cause great harm, your dog has voluntarily submitted to your leadership. You have earned his loyalty and his undying love. He displays his commitment and devotion to you through following you around, seeking to be near you, protecting you if necessary, and through laying his paws, head, or body on you whenever possible. Touch is a valuable communication tool. Your dog expresses his love for you in this manner. This is something that is easy for us to understand. What is more puzzling is how your dog selects the place where he will rest his head. Why your feet? Is this resting spot common to all dogs?
Encouraging the Behavior
There is no solid research to support why your dog selects one part of your body as his favored resting place over another. However, there are several logical conclusions we can draw with regard to this. Since most heat is released from the head, it is possible that your dog might select an area of your body that is cold as the place for him to rest his head on. Why? Dogs take their role as your companion and protector very seriously. It is possible that your dog is simply trying to conserve heat and transfer some of his to you to warm you up. The instinct to survive is well-preserved in our modern canines. It may be that your dog is simply fulfilling an instinct to protect his pack leader. Keeping warm would play a vital role in this strategy. Extremities such as human feet and hands (paws in the canine) that succumb to cold or frostbite could lead to grave illness and even the death of the pack leader. This would put the entire pack at risk, and no dog wants to have that happen. Equally plausible is the opposite theory. Dogs are essentially furry little opportunists. They may select the area of your body that is giving off the most heat in order to keep themselves comfortable and warm. This again could be traced back to the instinct to survive.
There is also the possibility that this is a random choice based more on convenience than any other logical reason. Your feet might be the most easily accessible area of your body for your dog to rest his head on at that particular moment. Of course, it is also possible that your feet are actually comfortable. Just because humans enjoy propping themselves up on plush surfaces does not necessarily mean that your dog feels the same way. Perhaps Fido enjoys the feeling of your velvety spa socks against his neck. Or the warmth emanating from your bare skin combined with the scent that is uniquely you provides him with a feeling of contentment and connection. Fido has his reasons, but he's rather tight-lipped on the matter!
Other Solutions and Considerations
Finally, it could be that Fido just wants your attention and putting his head on your feet is the best way to get it. If doing this in the past has elicited the desire response from you, chances are Fido is going to keep offering this behavior because he has learned that it yields the right results. If you would prefer that Fido find an alternative location to rest his head, you can teach this by redirecting to a different area of your body then rewarding him with praise and food or toy rewards. Dogs respond exceptionally well to positive reinforcement and catch on quickly when they do things that bring us pleasure. Since by nature our dogs do want to please us, behaviors that are rewarded and that also bring us obvious joy are things our dogs are going to offer to us again and again in the hopes of a similar reaction.