I know there are many discussions on here about this. But, I don't have the patience to go through each one. So, I have a question. I sometimes make food for my dogs. I use the right amount of all the ingredients, but, I also add ground flax seed. I've read that it is extremely good for the skin and fur of dogs. It has Omega 3 fatty acids in it. Can I just use that instead of other vitamins? B/c don't the dogs get the vitamins they need from the other foods or do I need to add more vitamins? If so, what extra vitamins do I need?