A study in the United Kingdom has added to evidence that dried meat dog treats can be contaminated with Salmonella.

Researchers also found some product samples contained similar types of Salmonella identified in human patients, prompting them to urge hygiene measures, including thorough handwashing by dog owners, pet food retailers, and veterinary professionals.

A selecion of dried treats from local pet shops and online retailers were tested for Salmonella in the UK. Treats were purchased from an independent pet shop and a large nationwide chain in Merseyside, and also from two nationwide-supplying online retailers from September to October 2021.

Air or freeze-dried and dehydrated treats have not undergone cooking or heat treatment as part of production; however, the process used must have been proven in sampling tests to destroy Salmonella.

Eighty-four samples were tested. Animal proteins included buffalo/bison, chicken, beef, lamb, pork, duck, rabbit, and camel, according to the study published in the journal Vet Record.

A variety of Salmonella detected
Salmonella was isolated from 13 treats. Samples that tested positive were dried bull’s penis “pizzle sticks,” bison ears, furry rabbit ears, and dried chicken treats. All positives came from the same independent pet shop on two separate visits. 

This could represent a local problem, but could also be a result of contamination at the supplier’s or within the supply chain, and without further environmental sampling, it was not possible to identify wher within the production chain contamination occurred, found the study.

Salmonella types found were Salmonella Anatum, Derby, Dublin, Infantis, and monophasic Salmonella Typhimurium. The most frequently isolated serotype was Salmonella Derby six times from bison ears, with Salmonella Dublin in two pizzle stick samples. 

Salmonella Derby and monophasic Salmonella Typhimurium strains were genetically similar to patient samples but there was no epidemiological information to confirm a connection. The risk of transmission to humans has been linked to a lack of hygiene following the handling of dog treats or contact with animals that may shed Salmonella in their feces.

Treats from the independent pet shop were unpackaged with no labeling or traceability information. Those from the nationwide chain were individually wrapped in branded plastic sealed packets.

Treats from the first online retailer were delivered in a box with some loose unpackaged ear snacks and other items in branded sealed bags. Those from the other online seller came as multiple items in clear plastic bags with no labeling.

Country of origin was unknown for the majority of treats, although four were produced in the UK, and a quarter stated materials were sourced from the UK and Europe on their website. A lack of information on origin poses a risk of importing Salmonella serotypes not commonly reported in the UK and highlights the importance of clear labeling for traceability, said scientists.

Government guidelines state that dog chews must be packed in unused packaging. However, treats contaminated with Salmonella in the study were sold as loose items that could be picked up by hand and purchased in paper bags.  

“Efforts should be made to educate dog owners further regarding the potential risks posed by these treats if they choose to feed them, especially in households with higher risk individuals present, such as immunocompromised individuals or young children. The importance of hygienic practice surrounding their use should be stressed, particularly regarding handwashing after use and consideration against feeding them within the home environment,” said researchers.

Raw-meat-based diet risks
Meanwhile, another study looked to see if raw meat-based diets (RMBDs) for pets are a source of bacteria with linezolid resistance genes. Such bacteria may spread from animals to humans upon close contact between pets and their owners.

Fifty-nine samples of RMBDs from 10 suppliers in Germany and Switzerland were screened for florfenicol-resistant Gram-positive bacteria. A total of 27 Enterococcus faecalis, Enterococcus faecium, and Vagococcus lutrae isolates were obtained from 24 samples. Researchers found genes that may confer resistance to linezolid.

Linezolid is a last-resort drug to treat some severe infections in people, according to a study published in the journal Eurosurveillance.

Samples were beef, poultry, horse, lamb, fish, rabbit, and venison and were bought between September 2018 and May 2020.

A high occurrence of florfenicol-resistant isolates in raw pet food made from meat primarily of European origin is concerning and underlines the need for its rational use in the agricultural sector, said scientists.

“The occurrence of isolates harboring linezolid resistance genes in raw dog food highlights the importance of promoting awareness of the possible risks associated with RMBDs and of providing information to pet owners on correct handling and feeding of RMBDs in order to mitigate potential health risks,” said researchers.