Ask a Vet: Why does my pet lick me so much?

Washington Post

6 hours ago

Q: Why does my pet lick me — and is it safe to let them do it?
A: Dogs and cats may lick humans to show empathy or affection — or simply to get your attention. For healthy adults, the risk of illness after being licked by a pet that receives regular veterinary care is negligible. But when dogs and cats lick people with weak immune systems, serious infections can follow. Here's what to know about why pets do this, and when you should be concerned.
More than 60 percent of U.S. households include a pet, for good reason: pet ownership reduces loneliness, depression and anxiety. Rustin Moore, dean of the veterinary school at Ohio State University and author of an upcoming book on the human-animal bond, says this bond 'has a profound power to heal, comfort and connect us; it is one of the most underutilized tools for improving human well-being.' Animal-assisted therapy is increasingly used in schools, nursing homes, hospices, prisons and hospitals, with benefits that include reduced pain perception, more rapid recovery from surgery, and improved emotional skills in children with disorders such as autism.
Licking is a common behavior in pets. In a 2020 study from Belgium, hand-licking by dogs was reported by 86 percent of owners — and face-licking by 50 percent of owners. In a study in the United Kingdom, more than 50 percent of people said their dogs licked visitors, too.
Animals lick other animals for many reasons. New moms lick their babies to clean and protect them (saliva has certain antibacterial properties, which also could explain why animals lick their wounds). Animals also lick one another during 'social grooming,' a bonding behavior that is particularly common in cats. A dog may lick humans to show empathy. And — given the opportunity — pets will meticulously lick skin that has traces of food or salty sweat on it.
When it's reinforced by positive social interactions (such as petting and a soothing voice), licking also can be a way to get attention. Genetics, other environmental influences, and age also influence licking behavior — in the U.K. study, younger dogs were more likely to lick people than older dogs.
In short, yes. Despite saliva's antibacterial effects, a pet's mouth harbors billions of bacteria just waiting to infect humans when introduced into open wounds. Within this 'bacterial soup' are two organisms with tongue-twisting names and a special ability to cause severe human disease: Capnocytophaga canimorsus (capno-sigh-toh-fah-gah canny-morse-us), a long, rod-shaped bug; and Pasteurella multocida (par-stew-rella mul-tee-sigh-dar), a tiny oval-shaped bug. Although I wish these organisms had nicknames, they don't — so I'll just call them Capnocytophaga and Pasteurella here (recognizing that there are other Capnocytophaga and Pasteurella species that are not important causes of human disease).
If you own a dog or cat, you probably live with these germs — they're found in most healthy dogs and cats. Capnocytophaga inhabits the mouth of more than 70 percent of dogs and 55 percent of cats, whereas Pasteurella is found in more than 50 percent of dogs and more than 70 percent of cats.
Although rare, Capnocytophaga infections are concerning, because they progress rapidly, and up to one-third of infections can be fatal. Within just a few days of a lick or bite, Capnocytophaga can multiply in your blood and cause critical organs to fail. These infections are also hard to diagnose, because Capnocytophaga grows slowly in the laboratory. The most severe form of infection — a gruesome gangrenous skin condition known as purpura fulminans — has a mortality rate of 60 percent. Survivors often face amputation of fingers, toes or limbs.
Pasteurella infections are more common, because Pasteurella is frequently involved in bite wound infections (think of it as the common cat bite bug). Much less often, serious Pasteurella infections follow licking, especially in babies or people that allow pets to lick open wounds or medical devices. With increasing animal ownership and advancements in human medical therapy, reports of Pasteurella infections of knee and hip replacements, peritoneal dialysis systems and long-term vascular access devices are increasing. 'We have seen serious Pasteurella infections that arose after cats — especially kittens — chewed on and contaminated dialysis equipment,' says Natascha Tuznik, an infectious-disease physician at the University of California-Davis. 'Such equipment should always be kept away from pets.'
While bacteria like Pasteurella and Capnocytophaga are very common in your pet's saliva, it's incredibly rare for people to get sick after being licked. Every year, millions of bloodstream infections occur in North America and Europe, but fewer than 600 Capnocytophaga infections and just 20 cases of purpura fulminans have ever been reported. Infections from licking are most likely to occur in infants, pregnant people, people over 50, or people with conditions such as AIDS, cancer, alcoholism, diabetes or organ transplants. Tuznik notes that 'people who lack a functioning spleen are particularly susceptible to Capnocytophaga infections and are specifically advised to avoid being licked by pets.'
Wash your skin with soap and water after being licked. Avoid sharing food dishes and utensils with your pet (no more fork feeding!). Prevent pets from licking open wounds or medical devices. And people in high-risk groups should limit contact to snuggles instead of smooches. If you (or people you care for) have a weak immune system and illness develops, tell your health care provider about any known animal contact. When doctors know which bacteria to suspect, the result is earlier treatment, faster recovery and fewer complications.
No! Remember, pet ownership can ease the emotional burdens often experienced by people with chronic illnesses. Even if your pet licks you, the chance of infection is minuscule. Talk to your doctor and veterinarian about ways to minimize the risk based on your specific health condition or life stage while keeping dogs and cats by your side.
Jane Sykes is a Professor of Veterinary Medicine at the University of California-Davis. She is a board-certified specialist in small animal (dog and cat) internal medicine with a special interest in infectious diseases. In addition to her veterinary degree, she has a PhD from the University of Melbourne, an MBA from the University of Georgia, and an MPH from Kansas State University, and is a Distinguished Fellow of the National Academies of Practice. She is the proud owner of two Labrador retrievers (Flora and Bodhi) and an orange tabby cat (Freckles).