Petco did not disclose the cardiac risks of WholeHearted grain-free dog food, a new class action lawsuit claims

Sarah Pepin filed a class action lawsuit against Petco Health and Wellness Co. Inc. on Sept. 7, 2026, in the U.S. District Court for the Southern District of California.

The complaint claims Petco sold WholeHearted grain-free dog food as complete, balanced nutrition while concealing research tying grain-free diets to potentially fatal heart disease.

Grain-free research

Dilated cardiomyopathy enlarges and weakens the heart's left ventricle until it cannot pump blood efficiently, and it can progress to heart failure and death, according to the complaint. Veterinary cardiologists began publishing research in 2018 tying DCM to grain-free diets heavy in peas, lentils and chickpeas, including in breeds with no known genetic predisposition, the lawsuit claims.

The U.S. Food and Drug Administration opened an investigation that July. It reportedly asked pet food companies to submit diet formulations for its investigation. Petco did not submit any information, the complaint alleges.

The studies cited in the complaint reportedly found:


  • Elevated NT-proBNP and cardiac troponin-I, markers of heart muscle stress and injury

  • Enlargement of the left ventricle

  • Irregular heartbeats

  • Cardiac improvement, including full reversal, after a switch to grain-inclusive food

The plaintiff's experience

Pepin says she bought WholeHearted Grain Free Beef & Pea Recipe multiple times for her two dogs, Douglas and Willow. The complaint alleges Douglas developed congestive heart failure and died in August 2026. Willow reportedly received a heart diagnosis the same month. Pepin claims the WholeHearted food caused both issues.

The food's label says "Complete Nutrition" and "Vitamins & Minerals for Balanced Nutrition," and the brand name and heart imagery together read as a promise about canine heart health, the proposed class action claims. Pepin says she would have paid less or not bought the food at all had Petco disclosed it could harm dogs.

What Petco's own veterinarians reportedly told customers

Certified veterinarians answer customer questions in a Q&A section on Petco's website. In July 2019, one veterinarian told an owner asking about a competitor's grain-free food that vets saw more DCM on those diets and recommended switching brands. Another, responding to a question about two rival labels, called grain-free food "a fad and a dangerous one." The complaint quotes both exchanges.

The lawsuit alleges Petco did not conduct any studies on the grain-free food before its 2016 launch and hasn't published any cardiac safety testing.

The legal claims

Pepin brings five causes of action:


  • California Unfair Competition Law, which bars unlawful, unfair or fraudulent business practices

  • Strict liability, design defect, which is a claim that the formulation itself is unreasonably dangerous

  • Strict liability, failure to warn, which highlight a seller's duty to disclose known risks

  • Negligence, which is a failure to use reasonable care in testing, labeling and selling the food

  • Connecticut Unfair Trade Practices Act, which is the state's ban on deceptive trade practices

The suit seeks actual and punitive damages, restitution, an injunction and attorneys' fees, and it places the amount in controversy above $5 million.

What the case means for WholeHearted buyers

The proposed nationwide class covers U.S. buyers who purchased the food on or after Sept. 7, 2022, with a Connecticut subclass covering purchases on or after Sept. 7, 2023.

No judge has certified either group. As of this writing, there is no settlement, no claims process and no money available.