In a large bowl mix together the flour, wheat germ, and salt. In a separate bowl, mash the banana with a potato masher or fork, and then mix in the peanut butter, bouillon mixture, and egg. Using a hand mixer fitted with dough hooks mix the liquids into the dry ingredients. Wrap the dough in plastic wrap and rest in the refrigerator for 15 to 30 minutes.
Preheat the oven to 350 degrees F. Line three sheet trays with foil.
Sprinkle some flour on a clean surface and roll the dough out to ⅛-inch thick. Using a bone-shape cookie cutter, cut out as many bones as you can. Place the treats on the prepared sheet trays, leaving only ¼ inch of space between. Repeat the process of rolling and cutting two more times. You should end up with about 45 dog treats.
Bake the treats until golden brown and slightly hard, 15 to 20 minutes. Turn off the oven, leaving the cookies inside to dry them out.
Store the treats in an air-tight container or plastic resealable bag in the refrigerator (up to 1 week) or freezer (up to 2 months). Thaw before serving to your pup.