On November 3, 2020, Plaintiff, on behalf of a proposed class of consumers, filed a class-action lawsuit in the U.S. District Court for the Western District of Washington against Costco Wholesale Corporation and Diamond Pet Foods Inc., alleging that the Defendants had jointly produced and marketed various dog food products under the Kirkland brand name as “Grain Free” when in fact, according to independent testing conducted by Plaintiff, they contained more than insignificant levels of wheat and other grains.

Specifically, both the front and the back of the Kirkland products labels included the “Grain Free” claim and the ingredient list did not disclose wheat or any other grains. Plaintiff alleged that allergies to wheat are common among dogs and that the purchasers of the Kirkland products paid a premium for them to avoid the risk to their pets.

A similar lawsuit was filed in September in the Central District of California alleging that, as established by independent testing, another of Diamond’s dog food products was falsely advertised as “Grain Free.” According to the lawsuit, Diamond had changed its labels several times, with the most recent label including a disclaimer that trace amounts of grains and other ingredients may be present as a result of the manufacture of other food in the facility. However, Plaintiff alleged that the disclaimer was insufficient since there was more than a trace amount of wheat present.

Although these lawsuits make the case that a grain free diet is one that is sought by many consumers, the FDA is investigating a possible link between diet and canine heart disease (canine dilated cardiomyopathy) and has stated that many of the reported incidents of canine heart disease have come from dogs on grain free diets. The FDA’s report states that grain free diets generally contain high levels of legumes, pulses, or potatoes, but that it is not known if there is any connection between these ingredients and canine heart disease; the report cautions that the correlation might simply be a result of the increasing market share of grain free dog food products.