Even puppies can benefit from green shakes!
Most fruits and vegetables have tons of fantastic health benefits for dogs, which can help prevent minor to major health issues in the future.
In my blender, I just put some water, then some of each: spinach, kale, peas, apple, banana, ground flax seeds, a little apple cider vinegar, and coconut oil! She likes carrots/cucumbers/celery a lot too, sometimes I put those in it as well.
