Can You Get Your Dog Sick?

Nina Pham, a Dallas nurse who was infected with the Ebola virus while caring for a patient, with her dog. (AP Photo/Courtesy of tcu360.com)

Not everyone being monitored for Ebola in Dallas is human. The infected nurse’s dog — a Cavalier King Charles spaniel named Bentley — has been quarantined for observation, since he was home with his owner, Nina Pham, when she developed a fever.

Although Bentley won’t be enjoying any strolls outside, Dallas city spokeswoman Sana Syed has assured the public that Pham’s furry friend isn’t going to be trapped in a cage for 21 days. “We’re going to do our best so that the dog is in the best mental state when he is returned to his owner,” she said. Another dog, Excalibur — the pet of a nursing assistant who caught the virus in Spain — wasn’t so fortunate: The 12-year-old rescue dog was euthanized, even though it was unclear whether the animal was infected with Ebola.

So is euthanasia — or just solitary confinement — even necessary? Could Bentley or Excalibur feasibly have caught Ebola from their owners? Research does shed some light on the subject: After the 2001-2002 Ebola outbreak in Gabon, about a third of dogs from villages with human cases tested positive for the virus, according to a study in Emerging Infectious Diseases.

“These findings strongly suggest that dogs can be infected by Ebola virus,” the researchers concluded. Interestingly, none of the furry patients developed Ebola symptoms, suggesting that infected dogs can appear to be healthy, yet may still shed viral particles in their urine, feces, and saliva until the Ebola clears.

But consider this: Many of these canines in the study had been feeding on infected animal carcasses or licking vomit off of sick people, the researchers reported. These circumstances aren’t likely among pets in the U.S. In fact, as the CDC recently stated, “The risk to pets is…very low, as they would have to come into contact with blood and body fluids of a person with Ebola.”

And, of course, most of us will never encounter Ebola, which means our pets aren’t likely at risk of exposure to it, either. But there are more everyday diseases that you could pass along to your pooch, said Whitney Krueger, an epidemiologist who has studied canine zooneses.

The biggie: methicillin-resistant Staphylococcus aureus, or MRSA, the type of staph that doesn’t respond to antibiotics typically used against the bacteria, Krueger said. How’s it transmitted? Most likely through direct contact — say, the bacteria is on your hand, and then you pet your pup, explained Ali Messenger, a public-health expert who has studied human-to-animal diseases.

And many of these human-to-dog transmissions may go unrecognized: “If someone had MRSA, and then their dog gets a skin infection, I don’t know if the vet would think to say, ‘Oh, well, you had MRSA, now your dog has MRSA,’” said Messenger. “I don’t know that many people make that connection.”

Related: First Ebola, Now Marburg. How Do We Stop Future Outbreaks?

That may explain why the research on “reverse zooneses” — the technical name for diseases that humans can give to animals — is somewhat lacking. In a study review, published earlier this year in PLOS ONE, Messenger was only able to track down 56 solid studies looking at this phenomenon “from the beginning of time to 2012,” she said. “It’s a relatively new topic. We’ve documented that this is happening. We just don’t know how prevalent it is.”

In fact, Krueger told Yahoo Health, “I think [instances in the research] were all very isolated cases, like when the pandemic H1N1 was circulating back in 2009, there was a report of a dog acquiring H1N1 from its owner.” When it comes to the flu in general, however, there is convincing evidence that transmission happens: “We have numerous cases confirmed, where people come down with the flu, and then within a week or so, animals develop respiratory disease and are confirmed to have influenza as well,” Christiane Loehr, an associate professor of veterinary medicine at Oregon State University, told Yahoo Health.

In humans and dogs, influenza symptoms — fever, difficulty breathing, coughing, sneezing — are the same, she said. It’s unknown whether a dog with the flu can pass the virus on to a human.

There is also some evidence that, in addition to MRSA and the flu, humans can pass along strep, E. coli, and herpes to their pets.

With the flu and strep throat, transmission typically occurs through droplets — “you sit on the couch, you cuddle with your dog, and you cough,” said Loehr — but otherwise, it’s generally through direct contact. “Say, in the case of Ebola, if you were bleeding and your dog came into contact with the blood. Or if you vomited and the dog came into contact with the vomit,” Messenger said. “Or if a companion animal licks your face and you have a cold sore, that could transmit herpes.”

For bacteria like E. coli, the fecal-oral route is also a possibility — for example, if you’re sick, use the restroom and don’t wash your hands, and then your dog licks your fingers, you could pass along the bacteria, added Messenger.

The reverse is much more well-documented: the transmission of diseases from animals to people. In fact, according to the CDC, there are hundreds of known pathogens, ranging from campylobacter to hookworms, that can spread from pets to people.

But don’t worry, there’s not a high probability that you’ll ever have to quarantine your own pup. “The risk to the average pet owner would be very low. If dogs are confined to the home, there is really no risk for that dog acquiring a pathogen,” said Krueger. “We’re more focused on people exposed to a large number of dogs in settings such as shelters or kennels, where the dogs are less likely to be healthy and are living in crowded situations.”

That said, if Fido spends a lot of time outside, he could pick up a pathogen, particularly gastrointestinal ones, like Giardia or campylobacter, through feces or contaminated food or water. “Then they can spread that through their feces,” Krueger said. “If a dog is infected and it excretes [the pathogen] through its feces, and then you were to walk barefoot on the ground or make contact with the feces in the house, transmission is possible.”

Related: Three Infections You Should Worry About More Than Ebola

The best way to protect yourself — and your pup — is to keep your animals up-to-date on vaccines and through simple hygiene practices. Read: If you’re exposed to canine feces or other bodily fluids, wash your hands immediately, and avoid roughhousing with your dog to a degree that could leave you scratched or bitten, cautioned Krueger. And when you’re sick, avoid kissing your dog or touching him without scrubbing up first. “It’s hard when you have a companion animal as part of your daily routine,” said Messenger. “But the best way to prevent the crossing of the barrier is to not have interactions.”