You might be surprised to learn that Dr. Daniel Griffin, chief of infectious diseases at Island Infectious Disease Medical in Long Island, N.Y., lets his two dogs lick him.
He’s not delusional. “We know how dogs greet each other,” he says. “We know where that tongue has been.” But he lets his expertise take over afterward. Griffin diligently washes his hands after his dogs lick them, especially before picking up a slice of pizza.
That’s more or less the expert consensus: love the pet, wash your hands. Living closely with pets brings you closer to germs, but for most people, ordinary contact is low-risk. There are exceptions, however. Here, experts answer the face-licking question and eight others about hygiene and animals you might encounter.
Should you let your dog lick your face?
First, forget the thing you may have heard your whole life. “I used to hear, ‘Oh, dogs’ mouths are like 10 times cleaner than people’s mouths,’” says Kelley Steury, a veterinarian and clinical associate professor at the University of Nevada, Reno School of Public Health. “I don’t think that’s based in science.”
A dog’s mouth, like a person’s, is full of bacteria. One species commonly found in dogs, Capnocytophaga canimorsus, can occasionally cause serious illness in people. Most of the time, though, nothing happens. “It doesn’t really pose a problem,” Steury says. The trouble starts when saliva gets past the body’s defenses—through a bite or into an open cut, for example. In rare cases, the infection can progress to sepsis and become fatal.
The risk also depends on who’s getting licked. People being treated for cancer or taking immune-suppressing drugs are more vulnerable to severe C. canimorsus infection. So are people without a spleen and those with alcohol-use disorder. But for healthy kids and adults, the occasional lick is fine, experts say.
Official guidance takes the cautious route, though: Keep dogs away from your mouth and face, and don’t let them lick open wounds. Saliva is more of a concern when it reaches broken skin or a mucous membrane, such as the mouth or eyes. If your dog gets you anyway, wash the area afterward. And if you’re immunocompromised or don’t have a spleen, ask your doctor what precautions make sense. But the fact that dogs, like so many of our daily exposures, can carry germs is not “a reason to not own a dog,” she says.
What if your cat licks you?
A cat lick is usually a non-event, too, provided your skin is intact. Cats commonly carry Pasteurella multocida, but on unbroken skin, Steury says, it “pretty much will not be a problem at all.”
Experts are more concerned about bites. A cat’s teeth are narrow and sharp, so they often puncture instead of scraping the surface. “The tooth acts kind of like a needle,” Steury says, “and it’ll inject that bacteria into your deep tissues.” What looks like a pinprick can be a deeper wound than it appears.
If a cat bite breaks the skin, wash it immediately with soap and running water and see a medical provider, Steury says.
What should you do about a cat scratch?
“I definitely respect the claws of cats,” says Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco.
If a claw catches you, wash your skin right away with soap and running water. The goal is to rinse the bacteria away before it settles in, not to disinfect. “Disinfectants don’t kill everything,” he says. “Running things are better than stagnant things in general.”
After that, pay attention to the area. Increasing redness, pus, or a fever over the next several days are all reasons to see a medical professional. So is a swollen lymph node on the same side of your body as the scratch, which can signal cat-scratch disease, a bacterial infection most common in kids. Location matters, too. Chin-Hong is extra cautious when a bite or scratch lands directly over a joint, where an infection can be harder to treat.
What if you have a fresh surgical site?
Coming home from surgery might be when you most want your furry friend on your bed. It’s also when experts want you to put a little distance between your pet and whatever is healing.
Dr. Ashley Drews, an infectious disease specialist at Houston Methodist, has seen patients develop infections after a pet licked an incision or surgical drain. “That’s not a good idea,” she says. Keep the site covered and your pet away from it.
Do you need to worry about the litter box?
Yes. Cats can shed Toxoplasma gondii in their poop, and the parasite can travel from the box to your hands to your mouth.
Yet the litter box isn’t the only way to get toxoplasmosis. The parasite can also turn up in soil, unwashed produce, contaminated water, and undercooked meat—especially pork, lamb, and venison.
“I think people are aware of the cat litter thing,” says Jill Roberts, a molecular epidemiologist and professor at the University of South Florida College of Public Health. Meat gets less attention. Roberts is so wary of undercooked pork that she skips thick cuts, which she worries are harder to bring to a safe temperature. “All I can see is Toxoplasma,” she says. You don’t have to give up pork chops, but you should use a food thermometer: Whole cuts of pork should reach 145°F. Once they come off the heat, wait at least three minutes before cutting or eating them; the meat’s temperature holds steady or continues to rise during that time, helping destroy pathogens.
While the pork chop may deserve more attention, the litter-box rule still stands. If you’re pregnant or immunocompromised, hand off the scooping if you can. If you have to do it yourself, wear disposable gloves and wash your hands afterward. Change the litter daily, too: The parasite takes one to five days after being shed to become infectious.
Can you catch your dog’s parasites?
Sometimes, but your dog’s diagnosis doesn’t automatically mean the whole household is next. When Griffin’s dogs had giardia, an intestinal illness caused by a microscopic parasite, he wasn’t panicking about catching it himself. “In general, it’s a different giardia that we get vs. dogs,” he says. The type that usually makes people sick isn’t the same type that usually infects dogs and cats.
Pay special attention during cleanup. Giardia can travel through tiny traces of feces on soil, water, fur, surfaces, and objects. Clean up dog poop promptly; keep up with veterinary care and parasite prevention; and clean the bowls, bedding, crates, and toys of a pet being treated for giardia. Your veterinarian may also recommend a bath to remove contaminated feces from its fur.
Always use actual soap and water after handling a sick pet or cleaning up poop. Sanitizer is helpful when it’s all you have, but it doesn’t remove dirt or every kind of germ.
Are your pets bringing ticks into the house?
Quite possibly. Your dog can come inside alone and still bring company. Dogs and cats can carry ticks indoors, where the ticks may disembark and choose a human for their next meal. Dr. Heidi Torres, an infectious disease physician and assistant hospital epidemiologist at Weill Cornell Medicine in New York, takes the possibility seriously enough to pack fine-tipped tweezers for overnight trips to the country.
Ticks are remarkably good at hiding in plain sight. On people, they tend to hide under arms, behind knees, around the waist, and in the hair. On dogs, check the ears, under the front legs, and between the toes. Torres says many people who develop Lyme disease or another tickborne illness “have no recollection of ever being bitten by a tick or ever seeing a tick.”
After spending time in tall grasses or woods, make sure everyone gets inspected. “Check yourself, check your partner, check your kids, check your dogs,” Torres says. If you find a tick attached to your skin, remove it then and there; waiting for a doctor only gives it more time to feed and potentially transmit disease. Use fine-tipped tweezers to grasp it close to the skin, pull upward with steady pressure, and then clean the bite and your hands. Finding a tick doesn’t automatically necessitate a trip to urgent care, but call your doctor if you develop a rash, fever, or other symptoms over the next several days or weeks.
What about backyard chickens and petting zoos?
Your pets aren’t the only animals capable of handing something off. More than 60% of known infectious diseases in people can spread between animals and humans, Steury says. The list of germs that can make the trip includes E. coli, Campylobacter, Cryptosporidium, and Salmonella—none of which care whether the animal carrying them looks clean.
Backyard chickens deserve special mention, in part because more people are keeping them. A chicken can look perfectly healthy and still carry Salmonella. Steury’s rules for handling them are uncomplicated: Wash your hands afterward, and “don’t kiss them,” she says.
The same logic applies at the petting zoo, with the added complication that children are extraordinarily efficient at putting their hands in their mouths. Steury isn’t telling you to skip it; just wash everyone’s hands with soap and water on the way out, and keep fingers and pacifiers out of mouths until you find a sink. Hand sanitizer is a useful backup, but it isn’t an equal substitute.
When does an animal encounter require a same-day phone call?
If an animal bites you hard enough to break the skin, or if you’ve had a possible encounter with a bat, seek medical care immediately. For animal bites, wash the wound right away with soap and water, then call a health-care provider—especially if the animal was wild, a stray, or behaving strangely, or if you don’t know whether it’s been vaccinated against rabies, a fatal disease that affects mammals.
The reassuring part is that less than 10 people die from rabies each year in the U.S., largely because most pets are vaccinated and people who may have been exposed can get preventive treatment.
The bar for what counts as a bat exposure is even lower because people may not realize they were bitten. “People think, ‘Well, I think I’d know it if a bat bit me,’” Steury says, “but you may not.” Bat teeth are so small that their bites can be painless or barely noticeable. If you wake up with a bat in your bedroom, find one near a sleeping child, or think you might have touched one, don’t open the window and shoo it out before asking what to do, Steury recommends. Call animal control or your health department. If it can be safely contained, health officials can test it for rabies. If it’s already disappeared, call anyway; public-health officials can determine whether you need post-exposure vaccination.
Steury knew a veterinarian in Alabama who had an unnerving encounter. “A bat just fell out of the sky and fell on her neck,” she says. It tested positive for rabies, and the veterinarian needed post-exposure shots even though she’d already been vaccinated in the past.
Of course, none of this means treating every animal like a biohazard. It means knowing what calls for soap, what calls for a phone call or doctor’s visit, and what you can stop worrying about. As Chin-Hong puts it, “The benefits of pets outweigh the disadvantages.”