Pet treats may carry Salmonella, CDC warns

Jun 30, 2006 (CIDRAP News) – Federal health authorities are warning that people should be careful with pet treats in the wake of a series of human Salmonella infections linked with treats made from raw salmon and beef.

Nine human Salmonella infections in western Canada and Washington state were traced to pet treats in 2004 and 2005, and hundreds of similar cases might have gone unreported, the Centers for Disease Control and Prevention (CDC) says in today's Morbidity and Mortality Weekly Report.

In view of the risk, the agency warns that people should wash their hands after handling animal-derived pet treats. Further, those at risk for serious illness, such as young children and immunocompromised people, shouldn't handle such treats at all, officials say.

The CDC also recommends that pet treat manufacturers use measures such as heat treatment or irradiation to kill bacteria in the products.

The report tells of nine cases, seven of which occurred within a few days after patients had handled beef or salmon pet treats. The patients were infected with a strain of Salmonella Thompson that matched the strain recovered from the treats. The other two patients had no history of handling contaminated pet treats, but they had dogs that carried Salmonella.

The reported cases included three in Washington state, four in British Columbia, and two in Alberta. The investigation led to two treat manufacturers, one in Washington and one in British Columbia. Both firms processed frozen, raw beef and salmon into pet treats by thawing, dehydrating, and packaging the meat.

"The dehydration temperatures were not high enough to kill bacteria that might have been present," the report says. "No processing step, such as irradiation, that would destroy Salmonella and other bacteria was used during the processing."

Cultures of treats from the plants yielded the outbreak train of S Thompson, the report says. Investigators found that salmon treats from one of the plants contained up to 80,000 colony-forming units of Salmonella per gram.

The CDC says previous studies have indicated that only about 1 in every 39 salmonellosis cases in the United States is reported and confirmed. Consequently, "this outbreak might have involved hundreds of infections."

Salmonella cases associated with pet treats are not new, the CDC says. In 1999, cases in several Canadian provinces were traced to pig-ear pet treats, and similar cases occurred in Alberta in 2002. Follow-up investigations showed that treats were often contaminated. For example, a 2003 study showed that 65 of 158 animal-derived pet treats bought in the United States in 1999 and 2000 carried Salmonella.

Canada does not regulate pet treats, but the US Food and Drug Administration (FDA) does; Salmonella-contaminated treats are considered adulterated, the CDC reports. The FDA began testing pet treats for Salmonella in 2004. Because testing indicates that contamination has not decreased, the FDA plans to step up its enforcement activities, the article says.

The CDC says consumers, pet treat makers, public health officials, and healthcare providers should be aware of the risk of contracting Salmonella from pet treats. The CDC and the Public Health Agency of Canada have issued recommendations for reducing the risk:

  • People should wash their hands with soap and water after handling animal-derived pet treats.
  • People at risk for infection or serious complications, including children under 5, older adults, and immunocompromised people, shouldn't handle such treats.
  • Pet store owners, healthcare providers, veterinarians, and treat manufacturers should inform pet owners of the risks.
  • Pet treat makers should take steps to kill bacteria, such as heat treatment or irradiation, and should put production information on labels.

CDC. Human salmonellosis assocated with animal-derived pet treats—United States and Canada, 2005. MMWR 2006 Jun 30;55(25):702-5 [Full text]

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