Dogs and many other animals instinctively lick scratches and wounds. This behavior stems from self-soothing actions and saliva's natural healing properties—but it's not without risks.
Like many mammals, dogs lick open wounds as an instinctive response to soothe irritation and pain. "It's similar to rubbing your foot after stubbing your toe," explains Dr. Kristi Flynn, a veterinarian and animal behavior expert at the University of Minnesota. "Or squeezing a burned hand for relief." Licking also helps remove debris, such as dirt or loose skin fragments.
Beyond pain relief, research highlights saliva's antibacterial properties, which promote tissue and nerve growth to speed healing. A 1990 study in Physiology & Behavior found dog saliva effective against Streptococcus canis—a bacteria common in animals—and even E. coli.
More recent research identified immune and cell growth proteins unique to dog saliva. Human saliva contains similar factors in smaller amounts, per a study in Archives of Oral Biology.
For pet dogs and cats, however, excessive licking can do more harm than good—especially after surgery, where it may damage or tear sutures. "Dogs turn a minor issue into a major one and lack the judgment to stop," notes Dr. Flynn. That's why vets often send pets home with an Elizabethan collar.
Canine saliva's antibacterial effects are not universal, and licking can introduce oral bacteria, raising infection risks. Yet this evolution-honed instinct persists because it's better than nothing—even if effective only part of the time.
Modern veterinary care outpaces evolution. While wild animals rely on licking, domestic dog owners should follow vet advice. Safer, faster healing options are now available.
