I recently started to add 1/2 teaspoon of flax seed oil and 1/2 teaspoon of apple cider vinegar to my dogs' food (Blackwood + ground turkey or ground beef). After 4 days, their coats are looking AMAZING! Shiny and glossy as can be. Also, they have no doggie smell whatsoever (more time between baths, thankfully) . Their eyes are bright and buzzing with energy. One side effect though is that it sometimes stimulates the anal glands if you know what I mean (e.g., stinky discharge). Too much flax and acv and their stools get loose. They seem to do okay on the 1/4 - 1/2 teaspoon range (my 3 dogs all weigh between 45 - 65 pounds). I think I will try adding canned pumpkin to their food as well to firm up the stools. One suggestion -- don't give the flax/acv to your dog for his/her morning meal if they don't have access to the backyard since they may need to go to the bathroom more than once.