Animal & Veterinary

CVM Issues Field Assignment to Collect and Analyze Samples of Pet Foods, Pet Treats, and Pet Nutritional Supplements in Interstate Commerce in the United States for Salmonella

Date: March 22, 2013


FDA’s Center for Veterinary Medicine (CVM) is concerned about animal feeds serving as vehicles for transmitting pathogenic and antibiotic-resistant bacteria to humans and other animals and is particularly concerned about Salmonella being transmitted to humans through pet foods, pet treats, and pet nutritional supplements that are intended to be fed to animals in homes, where they are likely to be directly handled or ingested by humans. In this document, “animal feed” is used to mean “food” for animals, as defined in section 201(f) of the Federal Food, Drug, and Cosmetic Act (the Act).

The association between human outbreaks of salmonellosis and contact with Salmonella-contaminated pet foods and pet treats is well established. Health Canada informed FDA of Canadian outbreaks of human salmonellosis that were linked to Salmonella Infantis in pig-ear dog treats that were manufactured in Canada in 1999 and to Salmonella Newport in beefsteak-patty dog treats that were manufactured in Texas in 2002. In addition, human outbreaks of salmonellosis in Canada and the United States in 2005 were linked to pet treats contaminated with Salmonella Thompson. Moreover, the Centers for Disease Control and Prevention (CDC) reported that, from January 1, 2006 to October 31, 2008, 79 human cases of salmonellosis were linked to Salmonella Schwarzengrund in dry dog foods that were manufactured by a company in the United States. More recently, in 2012, 49 individuals were infected with Salmonella Infantis, which was linked to dry dog foods that were manufactured by a company in a single facility in South Carolina.

Pet foods, pet treats and pet nutritional supplements if contaminated with Salmonella pose a health risk to humans. Certain vulnerable populations such as children, the elderly, and individuals with compromised immune systems, are particularly susceptible to Salmonella infection from such animal feeds. For these reasons, CVM considers it prudent to keep Salmonella-contaminated pet foods, pet treats and pet nutritional supplements out of interstate commerce.


All samples under this nationwide assignment will be collected from domestic products of pet foods, pet treats and pet nutritional supplements in the United States. This assignment does not cover imported products in either import status or domestic imports.


The samples can be collected at the manufacturer, distributor, wholesaler, or retailer in which pet foods, pet treats, and pet nutritional supplements are manufactured, held or offered for sale or for consumption. If possible, a variety of products from different manufacturers and sources should be selected to support efforts to determine nationwide prevalence. This assignment, however, does not cover canned pet food.

For both official and investigational samples, follow the sample collection procedures as described in the FDA Investigators Operations Manual (IOM), Subchapter 4.3, Collection Techniques and the aseptic sample collection procedures as described in the IOM, Subchapter 4.3.6, Aseptic Sample. For official samples, ensure that the proper controls are collected as outlined in IOM 4.3.6; interstate commerce is documented; labels and labeling materials are collected and try to provide the address and contact information about the manufacturers/distributors/retailers on the sample collection report (C/R). For investigational samples, there is no need to document interstate commerce, for the investigational samples will be used for research purposes only.

For this assignment, sample size of each official sample should consist of 10 sub-samples with each sub-sample weighing approximately 200 g (7.1 oz). Each of these 10 sub-samples already includes the 702(b) portions.


Handle, identify, package and ship samples in ways to ensure sample integrity. Deliver samples to the laboratory promptly with the original storage conditions maintained as nearly as possible. Please refer to IOM, Subchapter 4.5, for details about sample preparation, handling, and shipping. Samples collected under this assignment will, in general, not require refrigeration, and should be shipped by overnight to the laboratory as soon as possible after collection. In those occasional instances where refrigeration may be indicated (e. g., moist feed), investigators should refer to the IOM or contact Dr. Xin Li (Phone: 240-453-6863; Email: at CVM for assistance.


Official samples: FDA’s servicing laboratories will analyze the official samples of pet foods, pet treats, and pet nutritional supplements for Salmonella.

AOAC Official Method 2004.03 [Determination of Salmonella in Foods by VIDAS (SLM) Immunoassay], an enzyme-linked immuno-fluorescent assay or 2011.03 VIDAS SLM EASY are to be used as the screening methods for this assignment. Refer to procedures outlined in the FDA’s Bacteriological Analytical Manual (BAM) online, Feb. 2011, chapter 5, Salmonella for the confirmatory method to use in this assignment.

Aseptically weigh approximately 37.5 g (~ 1.3 oz) from each of the 10 sub-samples to form a 375 g (13.2 oz) composite sample for Salmonella analysis. Prepare pet treats and chews for Salmonella analysis using the procedures outlined in the BAM, chapter 5, section C (Preparation of foods for isolation of Salmonella), sub-section 20 (Pig ears and other types of dog chew pieces).

If a sample is positive for Salmonella, the servicing lab will send each Salmonella isolate to DEN-LAB for serotyping, and retain each duplicate Salmonella isolate in the laboratory. All serotyped Salmonella isolates will be sent to DEN-LAB for antimicrobial-susceptibility testing.

In addition, each servicing laboratory will conduct a pulsed-field gel electrophoresis (PFGE) analysis on each Salmonella isolate found under this assignment.


The Center for Veterinary Medicine (CVM) intends to support advisory/regulatory action against pet foods, pet treats, and pet nutritional supplements if they are found to be contaminated with Salmonella, and their manufacturers, for which interstate commerce can be documented under this assignment.

For each sample of pet foods, pet treats, and pet nutritional supplements found to contain Salmonella, districts should initiate procedures to remove the contaminated feed from interstate commerce, to inform the responsible firm of the need to initiate corrective action to prevent future contamination, and to recommend the issuance of a Warning Letter. In addition, within 90 days of being informed by the laboratory of the finding of Salmonella in a feed sample, CVM will request the district, in which the manufacturing firm/importer is located, to conduct follow-up investigations of the facility or facilities where the violative sample was manufactured to review manufacturing and handling procedures, document what corrections, if any, were made, and collect follow-up samples.

Contact FDA/CFSAN in cases involving human food contaminated with Salmonella.

Daniel G. McChesney, Ph.D.
Director, Office of Surveillance and Compliance

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