When ‘truths’ collide: Darwin’s, ANSWERS, and the FDA. An update

On September 20, 2024, the US Food and Drug Administration (FDA) issued an Advisory warning pet owners not to feed certain lots of Darwin’s Natural Pet Products foods to their dogs and cats. The Advisory cited findings of Salmonella in three batches of dog food and three of cat food. One of the dog foods also was contaminated with Listeria monocytogenes.

Darwin’s resisted the FDA’s recommendation of a formal product recall. Instead, the company chose to contact its customers directly and inform them of the FDA findings. Darwin’s posted a memo on the company’s website advising its customers of the FDA’s results, while claiming that the FDA Advisory was unnecessary and based on flawed regulatory decision-making.

The company also cast doubts in its memo about the validity of the test results reported by the FDA, and about the significance of what it referred to as “trace” amounts of pathogens in pet food.

On September 23, 2024, the FDA issued an Advisory warning pet owners not to feed certain lots of ANSWERS pet food products to their dogs. This Advisory cited the presence of Salmonella and/or Listeria monocytogenes in four batches of ANSWERS dog food. The FDA collected and tested these samples in response to three separate consumer complaints reporting sick pets.

ANSWERS also resisted the FDA’s recommendation of a product recall, opting instead to initiate a ‘voluntary withdrawal’ of the four contaminated batches. The company’s voluntary withdrawal notice stated that no illnesses associated with the contaminated batches had been confirmed.

A voluntary withdrawal is not subject to the same FDA oversight as a formal recall.

On September 25, 2024, Sue Thixton, writing for the Truth About Pet Food blog, accused the FDA’s Center for Veterinary Medicine (CVM) of lying about the nature of the response of both Darwin’s and ANSWERS to the FDA’s recall recommendations.

When is a recall not a recall?

According to published FDA guidance,

Recall means a firm’s removal or correction of a marketed product that FDA considers to be in violation of the laws it administers and against which the Agency would initiate legal action, e.g., seizure. Recall does not include a market withdrawal or a stock recovery.

When a company initiates a voluntary recall, it triggers a formal oversight process. In addition to determining the level of risk to consumers (ie., classification of the recall as Class 1, 2, or 3), the agency also participates in publicizing the recall and in overseeing effectiveness checks to verify that all consignees of the recalled product have been notified. In addition, all recalls are listed in the FDA’s weekly Enforcement Report.

A voluntary market withdrawal is not a recall. It is defined as “a firm’s removal or correction of a distributed product which involves a minor violation that would not be subject to legal action by the Food and Drug Administration or which involves no violation, e.g., normal stock rotation practices, routine equipment adjustments and repairs, etc..”

The FDA issued guidance for Public Warnings and Notifications of Recalls in 2019. This guidance document clearly lays out circumstances under which the agency may issue its own public advisories. For example,

“The FDA may issue or supplement a firm’s public warning, among other actions, in the following situations: a firm refuses to issue its own public warning when recommended or requested by the FDA, an ongoing recall or public warning is not prompt or effective, or the FDA learns of a completed recall where new adverse events associated with the product are reported after completion of the recall.“
“In some situations, the FDA may prepare and issue public warnings on its own initiative and in accordance with 21 CFR § 7.42(b)(2). This may occur, for instance, when the public needs immediate warning concerning a product and the firm has not issued a public warning or a firm’s public warning is deficient.“
“If a firm issues a public warning that is deficient in any respect… the FDA may supplement or correct that warning with its own public warning.”

Did the FDA lie to consumers by issuing Advisories?

No, it did not.

Darwin’s contacted its customers directly to advise them of the FDA findings, but has not initiated a recall. The FDA acted in accordance with its own guidance document by issuing a public warning about the contaminated pet foods.

ANSWERS chose to conduct a market withdrawal instead of accepting the FDA’s recommendation of a product recall. The wording of the company’s public notice downplays the level of risk to consumers and their pets by (a) denying any association between pet illnesses and the contaminated batches, and (b) referring to the market withdrawal as being undertaken “out of an abundance of caution.”

In its communication to customers (see below), ANSWERS instructed distributors and retailers to simply discard—instead of return—the products specified in the market withdrawal notice. A formal product recall would entail return of the recalled products to the manufacturer, followed by safe disposition as agreed to between the company and the FDA.

In both cases, the FDA acted in accordance with its own published guidance by issuing a public warning.

Are Salmonella and Listeria monocytogenes a health hazard for pets?

“There are thousands of species of Salmonella, less than a handful are harmful to pets or humans.” —Answers Pet Food product withdrawal announcement.

“Salmonella is not typically harmful to pets. ” —Darwin’s Memo Regarding FDA Statement

“Listeria monocytogenes rarely causes illness in dogs, but it is possible.” —Answers Pet Food product withdrawal announcement.

“Listeria is a microorganism that can affect humans, but rarely affects cats or dogs.” —Darwin’s Memo Regarding FDA Statement.

Fast facts about Salmonella and pets

There are some 2,500 to 3,000 known Salmonella serotypes.
Salmonella serotypes—and strains within each serotype—vary in their ability to infect, and cause illness to, dogs, cats, and humans.
Healthy dogs and cats can become ill as a result of a Salmonella infection, although they tend to be less susceptible than humans. Puppies, kittens, geriatric animals, and immunocompromised animals are more susceptible to serious illness than healthy adult animals.
Dogs and cats can become infected with Salmonella without showing any symptoms, and can shed the bacteria in their stools, contaminating the environment and putting other animals and humans at risk of becoming infected through contact with the animal (dogs and cats lick their butts and their coats, potentially transferring the bacteria to their mouths and fur).
In the years 2018–2024, the CDC encountered more than 80 different Salmonella serotypes in its investigation of multistate human disease outbreaks comprising 10 or more victims. The number of additional serotypes involved in small (fewer than 10 confirmed cases) or single-state outbreaks is unknown.
In 2023, seven people were infected with Salmonella Kiambu (a relatively uncommon serotype) as a result of contact with a dry dog food manufactured by Mid America Pet Food.
In 2018, a raw pet food manufactured by Blue Ridge Beef was the cause of two kitten deaths due to Salmonella.
In 2018, Darwin’s products were linked to six reported pet illnesses, including one dead kitten due to Salmonella.

Fast facts about Listeria monocytogenes and pet food

Listeria monocytogenes infections are uncommon in pets, but they can occur.
Infected pets may shed Listeria monocytogenes in their stools and their saliva even if they are asymptomatic.
The FDA is not aware of any documented case of a person acquiring a Listeria monocytogenes infection from a pet food.

Do numbers matter?

In its voluntary withdrawal announcement, ANSWERS states that it has not received any quantification data from the FDA. Darwin’s referred to the pathogens as being present in “trace amounts” only. Does the concentration of Salmonella or Listeria monocytogenes in a sample matter?

Numbers are meaningless in an absolute sense, although higher numbers usually enhance the risk of infection.

Some strains of bacteria are more virulent than others, and can cause an infection even if present at very low levels in a food sample. The immune status of the victim (whether animal or person) also is a factor. In addition, bacteria are not distributed uniformly through a food, especially a solid food.

Therefore, the issue of “quantification” is a red herring.

What does it all mean?

In short, while Salmonella and Listeria monocytogenes are less likely to cause symptomatic infections in pets than in people, these infections can occur—most commonly in immunocompromised animals, including puppies, kittens, and geriatric animals. These infections, even if asymptomatic, can be transmitted to the environment and to people who come into contact with the animals.

Darwin’s and ANSWERS try to rationalize the presence of ‘trace amounts’ of these pathogens in their products by pointing to the relatively low probability of them causing harm to healthy animals. This is akin to saying that Listeria monocytogenes should be allowed in human food because the risk to healthy people is low.

The FDA maintains a “zero tolerance” policy for the presence of pathogens in any ready-to-eat food, whether for human or animal consumption for a very simple reason. There is no other way to ensure a reasonable level of safety.

Did the FDA play fair with its testing methods?

Darwin’s claims, without providing supporting documentation, that its products tested positive for Salmonella only after an incubation period that lasted for multiple weeks, and were negative for Listeria when tested using conventional methods.

According to the company’s Memo Regarding FDA Statement, the agency began its inspection on August 26, 2024, and furnished preliminary ‘inconclusive’ results to Darwin’s on August 30, 2024.

On August 30th, Darwin’s initiated testing of the suspect batches by a third-party lab.

On September 7th, the third-party lab reported negative results for Listeria, and “very small trace amounts of salmonella.”

On September 20th, Darwin’s claims to have received FDA’s final test results.

How does the FDA test for Salmonella and Listeria?

“The FDA relies on the validated and internationally recognized testing methods described in the Bacteriological Analytical Manual (BAM).” according to a spokesperson for the agency’s Center for Veterinary Medicine.

BAM is available in its entirety on the FDA’s website. Methods for Salmonella testing in a wide range of foods are specified in Chapter 5. Listeria methods are contained in Chapter 10.

Screenshot of the procedural flowchart included in BAM Salmonella Chapter 5

The result reported to Darwin’s on August 30th would have been based on the appearance of the TSI and LIA slants. While not definitive, this is highly suggestive of Salmonella.

The presumptive positive result would have undergone further confirmation via more extensive biochemical and serological testing, possibly followed by whole genome sequencing for strain-level identification.

The method for detecting Listeria monocytogenes is similar in concept but differs from the Salmonella method in details of culture media formulas and lengths of incubation. It consists of:

An enrichment period of 24 to 48 hours
Selective plating onto 2 culture media, which are incubated for 24 to 48 hours
Sub-culturing individual suspect colonies onto another culture medium for confirming tests

Again, confirmation of presumptive positive Listeria monocytogenes results would include additional biochemical, serological, and/or DNA amplification tests.

Why was the third-party lab unable to find Listeria?

There are three possible explanations.

The third-party lab may have used a different test method
The third-party lab may have used a smaller sample size
Uneven distribution of the Listeria throughout the product

Not all pathogen-detection methods are equally sensitive (ie., able to find low levels of a pathogen). Methods used by the FDA have been validated in international studies for both sensitivity and accuracy. Darwin’s has not revealed what method their third-party lab used to test for Salmonella and Listeria monocytogenes.

A second major factor in detecting pathogens is the sample size used in the test. For the type of product in question, BAM specifies testing a total of 750g of product for Salmonella (if that much product is available) and 25g for Listeria monocytogenes. If the third-party lab tested a smaller quantity of product, it would be less likely to find the pathogens.

Finally, bacteria are rarely distributed uniformly throughout a batch of solid food. Detecting the presence of Salmonella or Listeria monocytogenes in an individual sample drawn from a large batch of product is a hit-or-miss proposition at the best of times. That is why the FDA places so much importance on environmental, raw material, and in-process sampling rather than reliance solely on finished product testing to ensure product safety.

A history lesson

Relations between the FDA and Darwin’s and between the FDA and ANSWERS have been problematic and sometimes acrimonious for several years. Indeed, both companies have taken the FDA to court—unsuccessfully—in the past.

The litany of past disputes is too long to include here. Anyone interested in the background can read about it in TOXIC. From Factory To Food Bowl, Pet Food Is a Risky Business.

For now, a sampling of recent history will suffice to set the scene.

Darwin’s Natural Pet Products

In February 2023, the FDA issued a Warning Letter to Arrow Reliance, Inc. (aka Darwin’s Natural Pet Products), citing three unresolved violations documented during an August 23, 2022, through September 30, 2022, inspection of the company’s manufacturing facility in Tukwila, WA.

The FDA found two different Salmonella serotypes in samples of Darwin’s cat food. The company responded by disputing the FDA’s stance that the presence of Salmonella in their products rendered them adulterated.
The FDA noted that the company had continued to use an unapproved food additive (peroxyacetic acid or PAA) to control pathogenic bacteria in its products, even though the company had been notified in August 2021 that PAA was not “Generally Recognized As Safe” in the context of its use by Darwin’s. In the intervening time period, Darwin’s had increased the concentration of PAA in its products substantially without any documentation to confirm either the safety of the higher concentration or its effectiveness in controlling pathogens.
The FDA informed Darwin’s that it was not exempt from registering as a food facility with the agency, despite the company’s insistence that it functioned as a retail food establishment and was not required to register with the FDA.

The FDA still considers this to be an ongoing investigation and has declined to comment on whether or to what extent the company has since addressed the issues raised in this Warning Letter.

ANSWERS Pet Food

According to information posted in the FDA’s on-line inspection database, the agency conducted an inspection of ANSWERS Pet Food’s manufacturing facility in March 2023. FDA inspectors documented five areas of concern, reproduced verbatim here:

Sanitation. You did not clean, maintain and store utensils and equipment in a manner that protects against contamination.
Hazard Analysis. You did not identify and evaluate each known or reasonably foreseeable hazard for each type of animal food you manufacture, process, pack or hold in your facility.
Preventive Controls. You did not identify and implement preventive controls to ensure that any hazards requiring a preventive control are significantly minimized or prevented.
Sanitation Controls. Your sanitation controls did not include procedures, practices, and/or processes that ensure sanitary conditions are adequate to significantly minimize or prevent hazards.
Supply-Chain Appropriate Verification Activities. You did not determine, conduct and document appropriate supplier verification activities.

The inspection result was classified as Voluntary Action Indicated, meaning that the company was given the opportunity to correct the outstanding issues on its own.

The bottom line

The FDA declined our request for more detailed information regarding the Salmonella recovered from samples of ANSWERS dog food, citing the agency’s policy of not commenting on an ongoing investigation.

For similar reasons, the FDA declined to comment on the details of testing methods used to analyze the Darwin’s samples, beyond stating that the agency used procedures described in BAM.

Nevertheless, certain things are clear, at least to this writer.

The FDA acted within its legal authority and guidance documents in issuing a public Advisory for both the Darwin’s and the ANSWERS findings.
Both ANSWERS and Darwin’s were disingenuous, at best, in their downplaying of the significance and risk associated with the presence of Salmonella and Listeria monocytogenes in their pet food products.
Both companies continue to produce pet foods contaminated with Salmonella and/or Listeria monocytogenes even after several years of attempts by the FDA to encourage the companies to take effective corrective actions.

Finally, one must ask, “When will the FDA’s Center for Veterinary Medicine take legal action to force these companies to comply with the law and institute the necessary processes and controls to ensure that the products they manufacture are safe for pets to consume?”

“A complete and compelling account of the hidden and not-so-hidden ways the food we give our beloved pets can be contaminated.” – JoNel Aleccia, Health Reporter, Food & Nutrition, The Associated Press.

“An invaluable resource for busy pet owners” – Food Safety News

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