Here is the short version, straight from the experts: love your pet, wash your hands. That is really most of it.
Yes, animals carry germs. So do doorknobs, grocery carts, and the grandkids. For most healthy adults, ordinary contact with a dog or cat is low-risk. But there are a few situations worth knowing about and a few that call for more than just soap.
We pulled together what infectious disease doctors, veterinarians, and public health researchers actually say about living closely with animals. Some of it will reassure you. A little of it might surprise you.
Should your dog lick your face?
First, forget the old saying that a dog’s mouth is cleaner than a person’s. Kelley Steury, a veterinarian and clinical associate professor at the University of Nevada, Reno School of Public Health, says that is not based in science.
A dog’s mouth is full of bacteria, including one species called Capnocytophaga canimorsus. Most of the time it causes no trouble at all. The risk goes up when saliva gets into a bite wound or an open cut. In rare cases, that infection can progress to sepsis.
Who is most vulnerable? People being treated for cancer, those taking immunosuppressive drugs, people without a spleen, and those with alcohol-use disorder face a higher risk from a serious C. canimorsus infection. For healthy adults, the occasional face lick is considered low-risk by experts.
Official guidance is cautious: keep dogs away from your face and mouth, and never let them lick an open wound. If your dog gets you anyway, wash the area with soap and water. If you are immunocompromised or do not have a spleen, ask your doctor what makes sense for your situation.
As Steury puts it, the fact that dogs can carry germs is not a reason to skip owning one.
What about cat licks, scratches, and bites?
A cat lick on unbroken skin is usually a non-event. Cats commonly carry a bacterium called Pasteurella multocida, but Steury says on intact skin it is generally not a problem.
Cat bites are a different story. A cat’s teeth are narrow and sharp, they puncture rather than scrape. Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco, says the tooth acts like a needle, pushing bacteria deep into tissue. What looks like a tiny pinprick can be a deeper wound than it appears.
If a cat bite breaks your skin, wash it right away with soap and running water and see a medical provider, Steury says.
For scratches, the same first step applies: wash immediately with soap and running water. The goal is to rinse bacteria away before it settles in. Chin-Hong notes that running water works better than disinfectants alone. Watch the area over the next several days. Increasing redness, pus, fever, or a swollen lymph node on the same side as the scratch can signal cat-scratch disease, a bacterial infection. A bite or scratch directly over a joint deserves extra attention, since infections there can be harder to treat.
After surgery, keep your pet away from the incision
Coming home from surgery is exactly when you want your furry companion close. It is also when the experts want 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 a surgical incision or drain. Keep the site covered and your pet away from it until it has fully healed.
The litter box and the pork chop
Cats can shed a parasite called Toxoplasma gondii in their feces. It can travel from the litter box to your hands to your mouth. That part most people already know.
What gets less attention, says Jill Roberts, a molecular epidemiologist and professor at the University of South Florida College of Public Health, is that the same parasite also turns up in soil, unwashed produce, contaminated water, and undercooked meat, especially pork, lamb, and venison. Roberts is cautious enough about undercooked pork that she skips thick cuts, which she worries are harder to bring to a safe temperature.
You do not have to give up pork chops. Just use a food thermometer: whole cuts of pork should reach 145°F. After taking them off the heat, wait at least three minutes before cutting or eating. The temperature holds or continues to rise during that time, which helps destroy pathogens.
The litter box rule still stands. If you are 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; the parasite takes one to five days after being shed to become infectious.
Your dog’s parasites and the ticks they bring inside
If your dog is diagnosed with giardia, that does not automatically mean you will catch it. Dr. Daniel Griffin, chief of infectious diseases at Island Infectious Disease Medical in Long Island, N.Y., explains that the type of giardia that usually infects dogs and cats is generally not the same type that makes people sick.
Still, cleanup matters. 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. Wash the bowls, bedding, crates, and toys of a pet being treated for giardia. Your vet may also recommend a bath to remove contaminated feces from its fur. Always use actual soap and water after handling a sick pet; hand sanitizer helps when it is all you have, but it does not remove dirt or every kind of germ.
Ticks are another concern. Dogs and cats can carry ticks indoors, where those ticks may then 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 that seriously enough to bring fine-tipped tweezers on overnight trips to the country.
Ticks are good at hiding. On people, they tend to tuck 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 notes that many people who develop Lyme disease or another tick-borne illness have no memory of ever being bitten or seeing a tick.
After time in tall grass or woods, check everyone: yourself, your partner, your grandkids, and your dogs. If you find a tick attached to your skin, remove it right away with fine-tipped tweezers. Grasp it close to the skin, pull upward with steady pressure, and clean the bite and your hands. Call your doctor if you develop a rash, fever, or other symptoms over the next several days or weeks.
Backyard chickens, petting zoos, and animal bites
More than 60 percent of known infectious diseases in people can spread between animals and humans, Steury says. That includes E. coli, Campylobacter, Cryptosporidium, and Salmonella, none of which care whether the animal looks perfectly healthy.
Backyard chickens deserve a mention because more people are keeping them. A chicken can look completely fine and still carry Salmonella. Steury’s rules are simple: wash your hands after handling them, and do not kiss them.
The same goes for the petting zoo, with one extra note: children are remarkably good at putting their hands in their mouths. The fix is straightforward: wash everyone’s hands with soap and water on the way out, and keep fingers and pacifiers away from mouths until you find a sink. Hand sanitizer is a useful backup but is not an equal substitute.
For animal bites that break the skin, wash the wound right away with soap and water, then contact a health-care provider, especially if the animal was wild, a stray, or behaving strangely, or if you do not know whether it has been vaccinated against rabies. Fewer than 10 people die from rabies each year in the U.S., largely because most pets are vaccinated and preventive treatment is available for people who may have been exposed.
Bat encounters deserve special mention. Bat teeth are so small 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 may have touched one, do not shoo it out the window. Call animal control or your local health department. If the bat can be safely contained, officials can test it for rabies. Steury describes a veterinarian in Alabama who had a bat fall directly onto her neck. It tested positive for rabies, and she needed post-exposure shots even though she had been vaccinated previously.
None of this is meant to make you eye your dog or cat with suspicion. As Chin-Hong puts it, the benefits of pets outweigh the disadvantages. It is really just about knowing when soap is enough, when to watch and wait, and when to pick up the phone.
