A study was conducted to survey the prevalence of Salmonella in imported and domestic pet chews in New Zealand to determine their potential to introduce novel pathogenic and antimicrobial-resistant Salmonella serotype clones into the home environment. Under the New Zealand Biosecurity Act 1993, Import Health Standards, imported chews must be in sealed packaging on arrival, be labeled with the country of origin, and be shelf-stable. Rawhide chews from countries other than Australia must be accompanied by an official declaration that the products have been soaked in a lime solution of pH 14 for at least 8 hours during processing to inactivate the porcine reproductive and respiratory syndrome (PRRS) virus that may contaminate porcine products. Three hundred samples of pet chews, both New Zealand-produced (domestic) and imported, were purchased. Salmonella was isolated from 5.3% of the imported and 6.7% of the domestic pet chews. Sixteen Salmonella isolates belonging to 9 serotypes were detected. Of the imports, pet chews from Australia had the highest prevalence (14%). Since these are not alkaline-treated, the findings indicate that Salmonella may be able to survive the dehydration process better than alkaline treatment. Contaminated chews are potential sources of Salmonella infection for domestic pets and humans who handle them.

COMMENTARY: Resistant strains of Salmonella have been isolated from animal-derived pet treats in the United States. In 2005, multiple reports of Salmonella-related illness in humans who had direct contact with pet chews prompted the Centers for Disease Control and Prevention to warn health care providers that animal-derived products should be considered possible sources of infection. As recently as March 23, 2007, pet treats were recalled in the United States because of Salmonella contamination. After ingesting contaminated food, apparently healthy dogs can shed viable organisms for 1 to 7 days, potentially contaminating the environment shared with other household members. -- M.C.DeBey, DVM, PhD, Diplomate ACVM

Salmonella serotypes isolated from pet chews in New Zealand. Wong TL, Thom K, Nicol C, et al. J APPL MICROBIOL 103:803-810, 2007.