FDA: Study of Salmonella in pet food just ‘routine’

Agency downplays concern about contamination

Published: November 18, 2011
By Bill Enfield

Salmonella Typhimurium, depicted here in a colored scanning electron micrograph, was implicated in a 2009 outbreak of infections affecting people and at least one dog who consumed contaminated peanut-butter products. Source: Getty Images.

Media coverage gave a false impression of a recent U.S. Food and Drug Administration (FDA) report that it will sample pet food, treats and supplements for possible Salmonella contamination, an agency spokeswoman said this week.

“I'm afraid that what has been reported in the media on this topic has been a bit disingenuous,” said Laura Alvey, a spokeswoman in the FDA’s Center for Veterinary Medicine. “This is a routine surveillance sampling assignment that we have been doing since 2007.”

She called the focus on Salmonella in household-pet food “merely this year's (fiscal year 2012) assignment.”

“The surveys have been for the same types of products each year — the only thing that changed from previous surveys was the title of this year's survey (which would probably explain the sudden media interest in something that is not new),” she said in an interview by email.

The previous Salmonella assignments were entitled "Nationwide Assignment to Collect and Analyze Samples of Direct-Human-Contact Feed from Interstate Commerce in the United States for Salmonella.” “Direct-Human-Contact Feed” includes pet foods, treats and supplements, as well as food for animals in petting zoos and agricultural fairs.
The latest Salmonella assignment is titled "Nationwide Assignment to Collect and Analyze Samples of Pet Foods, Pet Treats, and Supplements for Pets from Interstate Commerce in the United States for Salmonella.”

Alvey acknowledged that the Oct. 24 FDA memorandum about the new survey likely raised concern among pet owners and veterinarians, but she faulted the media for “inaccurate reporting” that intensified the concern.

The FDA announcement drew wide coverage by print, online and broadcast media. Several large news outlets characterized the action as a major move.

For example, the Wall Street Journal, the nation’s largest newspaper, reported: “The Food and Drug Administration has begun a nationwide effort to test pet food for Salmonella contamination amid evidence it is sickening pet owners.”

KTNV Channel 13 in Las Vegas described the action this way: “The FDA released a memo this week expressing concern that Salmonella is being transmitted to people through pet food. And now they're testing everything.”

Some reports tied the sampling action to Salmonella outbreaks — including one that occurred in 2006-07 that sickened 70 people — or to a study published in the journal Pediatrics in 2010 that linked pet food to illnesses in humans, particularly children.

Alvey said the FDA sampling is not in response to previous Salmonella outbreaks or to the journal article.

“Our goal here is to get an idea of how common Salmonella is in dry pet food, and then to determine which serotypes are most common and whether they are disease-causing pathogens,” she said. “There is no reason to believe pet food is unsafe.”

The FDA’s memo itself may have contributed to that perception, however, and it does not describe the study as “routine.”

In the background section of the memo, the link between human outbreaks of salmonellosis and pet foods and pet treats is said to be “well established.”

The memo outlines several such outbreaks going back to 1999, including the one cited in some media reports: “Moreover, the (U.S.) Centers for Disease Control and Prevention (CDC) reported that, between January 2006 and December 2007, 70 human cases of salmonellosis were linked to Salmonella Schwarzengrund in dry dog foods that were manufactured by a company in the United States.”

It goes on to say that Salmonella-contaminated pet products “pose a significant health risk to humans. Certain vulnerable populations such as children, the elderly, and individuals with compromised immune systems, are particularly susceptible.”

Salmonella is the leading cause of hospitalization and death among foodborne pathogens in the United States, according to the CDC.

Approximately 40,000 cases of salmonellosis in humans from all causes are reported annually in this country, but the actual number of infections may be greater by a factor of 30 or more, because milder cases likely are not diagnosed or reported, the CDC notes. About 400 people die from salmonellosis each year.

In the FDA survey just underway, the samples are being collected nationwide from outlets where pet food, treats or supplements are offered for sale or for consumption. Imported products and canned pet food will not be included.

The sampling was scheduled to begin in October and run through September 2012. The agency did not give a timetable for reporting results.

Whatever the impetus for the sampling, some veterinary medicine experts say the plan is a good one.

“This study will provide pet owners and veterinarians with better information about potential sources of Salmonella for pet dogs and cats,” said Dr. Sara D. Lawhon, assistant professor in the Veterinary Pathobiology Department in Texas A&M University’s College of Veterinary Medicine.

“Historically,” she said, “the sources of Salmonella for companion-animals are known to be raw meat and raw-meat diets, contaminated treats of animal origin such as pig’s ears, and predation on wild birds and rodents.”

Dr. J. Scott Weese, associate professor in the Department of Pathobiology at the University of Guelph’s Ontario Veterinary College in Canada, said: “Any move by federal bodies to pay attention to companion-animal issues is a major move because of the traditional focus on food animals and wildlife, with profound difficulties getting people to pay any attention to companion-animal issues.”

Weese said the sampling could provide better and more transparent information about Salmonella contamination of pet products. This information could, in turn, impel the development of “more standardized manufacturing and testing practices, especially for some high-risk products like raw animal-based foods and treats,” he said.

He added that public reporting on the prevalence of contamination in different pet products is important because while many manufacturers test for contamination, the results are not necessarily revealed to the public.

The FDA’s Alvey said data from the previous Salmonella sampling assignments are in a manuscript soon to be submitted by the agency for publication in a peer-reviewed journal. Sharing the details prior to publication will exclude the article from being considered for publication, Alvey noted, but she did offer this general result:

On average in the fiscal years 2007, 2008 and 2009, 9.8 percent of pet foods and 4.8 percent of pet treats tested were positive for Salmonella. Summary data for survey results in fiscal years 2010 and 2011 aren’t yet available.

Pet owners, veterinarians, industry and government have been particularly sensitive to contaminants in pet food since 2007, the year of the largest recall of pet food in North America. In that international incident, suppliers in China deliberately added melamine to wheat gluten and rice protein concentrate — ingredients used in pet food — in an attempt to boost the ingredients’ apparent protein levels. The fiasco affected 180 brands of pet foods sold in the United States and Canada and sickened tens of thousands of pets, many fatally.

Alvey said that since 2007, pet-product manufacturers have been required to report serious problems, including Salmonella contamination.

“The industry has become more aware, and acting when a problem is found,” she said. She pointed to new systems for reporting problems and exchanging information, such as the government’s Safety Reporting Portal (SRP) and PetNET. She said veterinarians are encouraged to report complaints related to pet food through SRP.

A detailed online archive of recalls maintained by the FDA since 2009 shows a sharp rise in recalls of products affecting pets due to suspected Salmonella contamination. There were three such recalls in 2009; 18 in 2010; and 11 so far in 2011.

The latest occurred Oct. 4. A cooperative in Ubly, Mich., recalled bags of soybean flour and bulk soy meal that may have been contaminated with Salmonella. The flour and meal are used in human and animal food.

The most recent recall involving just a pet product occurred Aug. 8. Merrick Pet Care of Amarillo, Texas, recalled 248 cases of its Doggie Wishbone treat because of potential Salmonella contamination.

The facts behind this year's recalls are less alarming than the rise in numbers might suggest, an examination of each incident shows.

Only one recall was related to illness from Salmonella-contaminated pet products: A dog in Missouri apparently was sickened by a pig-ear treat. The one sick dog led to three recalls in May by different manufacturers of similar treats, because the dog ate treats possibly from all three makers before becoming sick.

Thus far, none of the recall notices this year have cited human illnesses because of contact with the affected products.

In 2010, one recall was linked to possible human illness. On July 26 of that year, the FDA reported contaminated frozen reptile food (rats, mice, chicks) “may be related” to an unspecified number of human illnesses in 17 states.

Lawhon, the Texas A&M veterinary assistant professor, said it is unclear whether the rising number of recalls represents increased surveillance or risk. “Additional studies such as the upcoming FDA study are needed," she said.

Kurt Gallagher, director of communications and export development for the Pet Food Institute, an industry trade organization in Washington, D.C., said there is nothing inherent in how pet foods and treats are manufactured that would contribute to an heightened risk of contamination.

“Most pet-food products undergo some sort of cooking process, which acts as a kill step for microbes that potentially may be present,” Gallagher said. “This works similar to cooking chicken or hamburger.”

As to what might cause a pet product to become contaminated by pathogens, Gallagher said, “I wouldn’t want to speculate on that. Pet food is a very diverse industry. There lots of different manufacturing processes, so many different ways pet foods are made. You’d have to ask the individual manufacturers.”

As an example of one of the myriad ways in which contamination might develop, Gallagher pointed to the case of Salmonella in Peter Pan peanut butter in 2006: The manufacturer, ConAgra Foods, reportedly traced the problem to moisture from a leaky roof and faulty sprinkler, which allowed dormant bacteria in the plant to thrive and multiply.

Salmonella infection in cats and dogs, as with people, may manifest with diarrhea, anorexia, fever, malaise, vomiting and abdominal pain, although not necessarily all of those signs, according to Lawhon.
Salmonella infection and shedding should be considered in pet dogs and cats that are presented to their veterinarian with a history of diarrhea with or without additional clinical signs such as vomiting, anorexia and fever,” she said.

Infected animals may shed the bacterium for four to six weeks after the clinical signs have disappeared and remain “a source of infection for other members of the family,” she said.

“Prevention of Salmonella infection relies on good hygiene and care in food handling, particularly when handling foods prepared for infants, the elderly and the immunocompromised,” she added, advising: “In general, pet owners should wash their hands after petting, touching, handling or feeding pets."

Other possible sources of Salmonella for human infection include contaminated food — including meat and vegetables — and handling birds, reptiles and amphibians, she noted.

The FDA provides an online list of tips on how to avoid Salmonella infections from pets and pet products.

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