Early Neurological Stimulation (ENS)
ENS is something we start with our puppies at 3 days old. It consists of 5 exercises that we do with them once a day. We start with holding them in an upward position, head erect for 3 to 5 seconds. Then holding the pup firmly we rotate them to head down position for 3 to 5 seconds. Then proceed to supine position. Laying them on their backs with muzzle facing up for another 3 to 5 seconds. The last two exercises are thermal and tactile stimulation. The tactile stimulation is done with a soft object such as a cotton swab. We tickle their toes with it for 3 to 5 seconds. Lastly we do thermal stimulation. We place the pup, paws down on a cold washcloth. This is also for 3 to 5 seconds without the puppy being restrained. These exercises are done from day 3 of life to day 16 because it is believed to be the most crucial time for neurological growth. The U.S Military designed this method to better the performance of military dogs, which is stated by the Breeding Better Dogs Program.
There is a lot on the internet you can find for yourself about this if you are interested.