The US Food and Drug Administration (FDA) has issued a warning letter to Midwestern Pet Foods over contaminated products linked to more than a hundred dog deaths.

In a statement, the FDA said it had issued the letter after inspections of the company’s manufacturing sites revealed apparent violations of the Federal Food, Drug, and Cosmetic Act.

It said: “These conditions likely contributed to the illness or death of hundreds of dogs.”

The FDA said the initial inspection of Midwestern’s Chickasha, Oklahoma, plant was triggered by reports of illness or death in dogs that had eaten Sportmix brand dry dog food manufactured by Midwestern.

“Samples of Sportmix were later found to contain levels of aflatoxin as high as 558 parts per billion (ppb). The FDA considers pet food to be adulterated if it contains more than 20 ppb of aflatoxin,” it said.

Aflatoxins are toxins produced by the mould Aspergillus flavus which can grow on corn and other grains used as ingredients in pet food. At high levels, aflatoxins can cause illness and death in pets.

Steven Solomon, director of the FDA’s Center for Veterinary Medicine, said: “Samples of dog food were found to contain high levels of aflatoxin. It is imperative that manufacturers and distributors of pet foods understand their responsibility to comply with all requirements of federal law and FDA regulations and, when applicable, to implement a robust hazard analysis and risk-based preventive controls programme.

“We’ll continue to hold companies accountable and protect animal health as a core element of the FDA’s public health mission.”

In January, Midwestern voluntarily recalled these products, as well as all corn-containing pet foods manufactured at its Chickasha plant.

In March, it recalled several brands of pet food manufactured at its Monmouth, Illinois. plant after samples tested positive for Salmonella.

The FDA found that Midwestern’s food safety programme “appears inadequate to significantly minimise or prevent Salmonella in its pet food”, adding “none of the recalled products should be available to consumers to purchase”.

The regulator said that, as of 9 August, it was aware of more than 130 pet deaths and more than 220 pet illnesses that may be linked to eating brands of pet food manufactured by Midwestern.

It has requested a written response from the company within 15 working days stating the specific steps they have taken to correct any violations. The FDA said failure to adequately address any violations promptly may result in legal action, including product seizure and/or injunction.

The 15 day deadline ended yesterday (24 August).

Just Food has asked Midwestern Pet Foods for its response to the FDA’s warning letter.