How did a sedative used in euthanasia end up in cans of a premium brand beef dog food? The company behind the food, Evanger’s, would really like to know. So would the owner of three pugs that became sick and one that died after eating cans of Evanger’s Hunk of Beef.

Sodium pentobarbital is a sedative and sometimes used to control seizures and for insomnia in humans, but it’s most commonly used for euthanasia in cats, dogs, and horses, as well as other farm and companion animals that aren’t going to be eaten. It’s also used for human euthanasia in localities where that’s legal, and has been used for executions by lethal injection.

Because sodium pentobarbital is not intended for use in livestock that will eventually be consumed, everyone wants to know how it ended up in these cans of dog food. Evanger’s says it is investigating, but currently believes its beef supplier is the likely source.

The food came to the manufacturer’s and public’s attention after a family in Washington state fed a can of the food to their four pugs in early January, and all of the dogs immediately became ill. One of the dogs didn’t survive, and the other three spent time in veterinary intensive care before they recovered. They’re the only dogs known to be affected.

Lab tests showed pentobarbital in one lot of food, but the company is recalling four other lots to be safe. The product in question is Hunk of Beef canned food, and affected lot numbers are 1816E03HB, 1816E04HB, 1816E06HB, 1816E07HB, and 1816E13HB. The cans were manufactured in June 2016, and have an expiration date of June 2020.

Affected food was distributed to Washington, California, Minnesota, Illinois, Indiana, Michigan, Wisconsin, Ohio, Pennsylvania, New York, Massachusetts, Maryland, South Carolina, Georgia, and Florida.

Symptoms of accidental consumption of pentobarbital in dogs include drowsiness, dizziness, excitement, loss of balance, or nausea, and a large enough dose can cause death.

“All Evanger’s suppliers of meat products are USDA approved,” the company said in its statement. “This beef supplier provides us with beef chunks from cows that are slaughtered in a USDA facility. We continue to investigate how this substance entered our raw material supply.”

If you have any cans in the affected lots, return them to the store for a refund. If you have any questions about the recall, contact Evanger’s at 1-847-537-0102.