Meat by-products (MBP) from fallen animals “contain high levels of zoonotic and antimicrobial resistant (AMR)-harbouring bacteria that pose a transmission risk to dogs, their handlers, and the environment”.
This was the conclusion of a “first-ever” study recently published in the Irish Veterinary Journal to document the risks associated with feeding MBP from fallen animals to dogs.
The study’s main focus was to investigate the distribution of several bacteria in samples of MBP from knackeries and associated equipment and kennels.
The name of the study is: A survey of food-borne and antimicrobial resistance-harbouring bacteria in meat by-products from knackeries and associated equipment and kennels. Knackeries must adhere to strict rules regarding collection, transport, storage, use, processing, and disposal of MBP. But low-risk MBP from farmed animals that have not died of an infectious or systemic disease are legally permitted to be fed to dogs from listed kennels, packs of hounds, and dogs in shelters.
However, there is limited information available about the risks of spreading foodborne bacteria or AMR determinants to dogs, their handlers, or the associated environment, according to the study.
For the purpose of the study, and over a 12-month period, researchers collected:
- 313 fresh and 208 frozen MBP samples from 22 knackeries;
- 16 swabs of mincing equipment from two of the knackeries;
- 138 swabs from kennels adjacent to seven of the knackeries.
Where cleaning had not been conducted in the kennels, bedding with faeces was also collected.
Five different areas within each kennel were randomly sampled, taking precautions to avoid cross contamination, according to the study.
The bacteria under investigation in the study are: Salmonella serovars, Listeria monocytogenes, Campylobacter species, enterococci, their associated AMR determinant, and the level of Escherichia coli.
According to the study, “dogs in general are recognised as carriers of zoonotic bacteria, showing no clinical signs of disease in many cases”. However, there are some instances of fatal salmonellosis and campylobacteriosis in dogs as a consequence of contaminated pet foods.
Did you know?
Greyhounds and hunting dogs are currently classified as farm animals under Irish law.
Results
From the 521 MBP samples analysed, the following strains were recovered:
- 77 salmonella (14.8%);
- 101 L. monocytogenes (19.4%);
- 12 campylobacter (2.3%);
- 271 Enterococcus faecalis (52.0%);
- 127 Enterococcus faecium (24.4%) strains.
The 154 analysed environmental samples from kennels and mincing equipment yielded 194 isolates, comprised of:
- Three salmonella;
- 85 E. coli;
- 76 E. faecalis;
- 30 E. faecium.
E. coli was quantifiable in 423 of the 521 MBP samples.
AMR characterisation of 168 E. coli, enterococci and salmonella isolates from MBP and environmental samples showed high levels of AMR including multi-drug resistance (MDR) with 63.6%, 9.1%, 29% and 45.8% of E. coli, salmonella, E. faecalis and E. faecium isolates, respectively, showing resistance to three or more antimicrobials (MDR).
The study found, fewer salmonella, campylobacter and E. coli were found in frozen MBP than in fresh MBP, although freezing had little impact on levels of L. monocytogenes and enterococci.
Samples analysed for E. coli and enterococci showed high rates of contamination, reflecting the low standard of hygiene practices in knackeries, the study found.
Apart from the risks posed by the presence of zoonotic organisms in MBP, the study said, contamination with antimicrobial resistant bacteria also constitutes a potential risk for human and animal health.
Study’s conclusion
The findings of the study indicate that MBP may be a vehicle for transmission of zoonotic pathogens and antimicrobial resistant determinants to dogs, their owners and the environment.
The findings may also serve as the focus for future research to understand the risks to human and animal health associated with feeding this type of product to dogs.
MBP is a “rich nutrient matrix, which supports the growth of bacteria including pathogens” so fully eliminating all risks for product handlers, dogs and their owners is not achievable, so enhanced control measures should be considered instead.