Recently there has been a tremendous amount of information circulated that implicates feeding grain free veterinary diets as being one cause of Cardiomyopathy, a serious and potentially fatal disease of dogs and cats.  It has been known for many years that feline diets deficient in Taurine, an essential amino acid, can lead to cardiomyopathy in cats. If the diet is then corrected, often the disease will reverse. A theory was formulated that the same was true in dogs, and that grain free diets, some of which are low in taurine, lead to cardiomyopathy.  However, recent studies have failed to prove this.  Even though grain free diets are associated with an increased incidence of cardiomyopathy, the problem seems to go well beyond the taurine levels in the diet.  A recent overview of the state of the research led to the following conclusions: 

1. Feeding Grain free Diets appear to increase the likelihood of a dog developing Cardiomyopathy.
2. Although some of the Grain free diets are deficient in taurine, many are not.
3. In general certain breeds are more susceptible to cardiomyopathy than others.  Likewise these breeds may be more likely to develop food related cardiomyopathy.  
4. Many Grain free diets are high in legumes.   This may or may not contribute to the development of cardiomyopathy.
5. Pet owners should not feed Grain free diets exclusively unless there is positive scientific evidence that the pet is allergic to all grains (very rare).