In Save the Homeland, you have the ability to train your dog. To do this you will need a flute made by Louis. The flute cannot be bought, but you can still obtain one. Make sure to befriend Louis giving him many Walnuts and Eggs. Then one day when you visit Maple Lake, you will see him playing his Flute. He will give you one and then teach you how to play it.
To play the flute simply equip the flute. Then press the Square button, after that holding down the X button while you use the other notes to play (see below). The flute is used to give you a better conection between you and your dog. The more you train your dog, the more hearts he will gain. It may take some time before your dog reacts to some of the commands that you will play, but eventually he should react instantly when he loves you enough.
Bark: Left, Right, Left, Right
Heel: Left, Right, Right
Jump: Left, Up, Right
Lay Down: Up, Down, Down
Round up Cows: Left, Right, Left, Right
Sit: Up, Left, Down
Sit Up: Down, Up, Up