I just read about this powder as having a number or vitamins that preserve well on drying in a forum. There was a drumstick tree in my aunt's house full of very pretty and painful catapillars - I used to see the tamil neighbours take leaves from it.
Moringa’s fresh leaves have 7 times more vitamin C than oranges.
Dry leaves have 25 times more iron than spinach; 4 times more protein
than eggs; 10 times more vitamin A than carrots; 17 times more calcium
than milk; and 15 times more potassium than bananas.
The main greens dogs are crazy about is Lantana verbena or L. camara (Vervain, closely related to catnip) which is medicinal to them, though wiki claims that it is a poisonous plant - but it has been used medically as an anthelminthic and for epilepsy. It's very closely related to thymol and catnip so is probably a dewormer.
But their preferred green suppliment - what they love beyond anything else - is Dog grass or Couch grass (triticum repens) which they consume madly to deworm themselves and as a digestive.
Though this grass is supposed to be a very fast-spreading troublesome weed, it refuses to grow in my home. I've constantly transferred seed and whole plants, pampered it with water and compost but it dies.
I don't have a green thumb.:(I comfort myself by saying my ground is probably not acidic enough for them.)