New/old motor for the duster

We have a black lab, he is like 15 had him since a pup, wife trained him.
He pays me no attention, unless he wants something, I can walk in the door from work, he might open an eye.
Wife comes home from work, he greets her at the door, before she comes in the house.
The entire rest of the evening, he will shadow her so bad, if my wife stops walking, the dog will run into her.