Estimated read time: 4-5 minutes
- Household dogs may spread antibiotic-resistant salmonella, posing public health risks.
- A Penn State study found 77 cases of salmonella transmission from dogs to humans.
- Experts recommend hygiene practices, like handwashing, to prevent infection from pets.
SALT LAKE CITY — Your dog's a good companion who likes to greet you at the door with a thumping tail and toothsome grin. He's always happy to see you, and if you're down or feeling sick, he's right there to help you feel better.
But there's a chance your canine pal is responsible for that recent hard-to-shake stomach bug. A new study from Pennsylvania State University finds that household dogs can be a little-known contributor to the spread of antibiotic-resistant salmonella, which has become a serious public health concern. Dogs, the researchers say, are an "overlooked transmission point for zoonotic pathogens" including salmonella, which brings diarrhea, fever, cramps and sometimes life-threatening complications.
The findings are published in the journal Zoonoses and Public Health.
More than half of U.S. households reportedly include at least one dog. Cats can also spread illness.
Dog owners' hygiene habits, dog food safety and the medications given to our canine companions can all influence whether pets play a role in humans getting salmonella and how well the illness responds to treatment.
Additionally, not only are dogs and humans in close contact, but both are sometimes given antibiotics, increasing the risk of developing infections that become resistant to the antibiotics charged with killing bacteria. The Centers for Disease Control and Prevention said people may get salmonella from eating "contaminated food or from infected people or animals — typically via unintentional contact with feces via touching hand or stroking a pet," as a release from Penn State puts it.
The CDC estimates that more than 1.35 million infections in the U.S. are caused by the bacteria. Salmonella is the leading cause of hospitalizations and death in the U.S. when it comes to foodborne illness.
Dogs get salmonella. Sometimes you see symptoms, sometimes you don't, said Erika Ganda, assistant professor of food animal microbiomes at the university's College of Agricultural Sciences, who led the research. Because people and their pets are so close, salmonella can be transmitted between them, a process called zoonosis.
To study that, the team looked at all nontyphoidal salmonella strains isolated from domestic dogs in the U.S. Food and Drug Administration's Veterinary Laboratory Investigation and Response Network between May 2017 and March 2023. They then looked at the timing and location of those 87 cases and matched them to strains found in humans in the National Library of Medicine at the National Institutes of Health, which provides access to biomedical and genomic information. "They found 77 suspected cases where the bacteria moved from pet dog to person. A total of 164 strains were collected from 17 states that proved to be zoonotic."
Each of the strains had traits of antibiotic resistance related to drug classes the World Health Organization deems "critically important" or "highly important."
Paying attention to germ spread
The findings show a need for stewardship and biosurveillance that includes companion animals, said Sophia Kenney, a student in the Animal Sciences Department who spearheaded the study. She emphasized that animal and human health are closely related in a shared environment.
"Especially with salmonella, we think about the role of agriculture and transmission — we think about eggs, we think about beef. But the thing is, we don't let cows sleep in our beds or lick our faces, but we do dogs," she said. "We have this close bond with companion animals in general, and we have a really close interface with dogs. So, we asked the question: What's the role of companion animals in transmission of zoonotic disease like salmonella, since they can get it."
Those infections are typically linked to pet treat outbreaks, contaminated pet food and improper handling of pet food. The Penn State study cites as an example when more than 150 people nationwide were part of a multi-drug-resistant salmonella outbreak linked to pet treats made of pig ears.
Keeping Fido and his human friends safe
Simple hygiene is the best way to protect people and pets. Wash your hands often, said study co-author Nkuchia M'ikanatha, lead epidemiologist for the Pennsylvania Department of Health and an affiliated researcher in Penn State's Department of Food Science. "Our dogs are family, but even the healthiest pup can carry salmonella."
Don't touch your face while you're playing with the dog, either.
And if you're someone who lets your dog lick your face, you might want to reconsider. They lick other things as well, some pretty unsavory.
