There was a discussion about this issue a short while ago here on DT: https://www.dobermantalk.com/doberma...1-taurine.html
In the thread I linked, one of my comments has a link to a presentation that is public on Facebook by a veterinary cardiologist to the Doberman Club of Dallas. She does briefly discuss this issue.
Basically, the theory is that the heavy legume/pea content that is used in most grain-free foods is somehow affecting the way dogs are able to absorb taurine, thus causing taurine deficiency induced DCM (which is reversible depending on stage, if I understand correctly). They've found this as DCM has been popping up in a bunch of breeds not traditionally diagnosed with DCM, and the common link has been a grain-free diet.
The investigation is still in the early stage. Many cardiologists are recommending dogs be switched to more traditional, grain inclusive diets (or, some approve of appropriately formulated raw diets), providing your dog tolerates grains well (and most dogs do).
Personally, my dogs do just fine on grain. After doing a lot more research into dog nutrition from actual canine nutritionists (rather than self-proclaimed internet experts), I learned so much more about dog food and dog nutrition, and made some different choices about dog food.
This blog has some good posts on nutrition - she is a board certified veterinary nutritionist: https://weethnutrition.wordpress.com/
Richter & Sypha
Glengate's Mountain Fortress CAA ORT L1V NW1 L1I L1E L1C NW2 L2V L2I ACT1 RATI SOG WAC
& Sirai's Golden Masquerade ORT NW1 L1C L1V L1E L1I NW2 RATI SOG WAC
“You cannot get through a single day without having an impact on the world around you.
What you do makes a difference, and you have to decide what kind of difference you want to make.”
― Jane Goodall