Ditto Bailey's Mom's Comment... You're the BEST, Boxergirl!
From the stuff I've read on the grain-free/taurine/heart health issue, I've learned:
1. Dogs can produce their own taurine, given other amino acid building blocks (i.e. proteins). This is unlike cats... cats get their taurine directly from their food.
2. Legumes (and to a lesser extent potatoes) don't contain the right building blocks to make taurine, and also interfere with the ability of a dog's system to synthesize taurine, and therefore act as an anti-nutrient when it comes to taurine, potentially leading to taurine deficiency.
3. If your food looks to have lots of legumes (peas, lentils, garbanzo beans, etc) in high places of the ingredient list (or in multiple places, spread out), they are counting as both fiber AND protein in the ultimate nutritional analysis, displacing complete proteins, like meat. These are the foods that might cause problems. But, as Boxergirl's posts says - there may be contributing factors to why some dogs develop heart problems beyond just the food.
I'm once again very glad I feed a fresh, home-prepared, raw diet. I add in heart meat (high in taurine) a few times a month now. I find beef hearts at the local H-Mart (Asian grocery).
When I was feeding my cat raw (she's since passed... at 18 yrs old... not always fed "good" food, either)... I added a taurine powder supplement to her food, since taurine is one of those compounds that tends to oxidize quickly.