Each year, more than 4.5 million dog bites occur in the United States. Despite what you might assume, most of these incidents don't happen when an unfamiliar dog attacks someone in a park or another outdoor location. Instead, most dog bites are inflicted by a pet dog in a home.

Here's advice for avoiding these upsetting and potentially serious injuries — and the steps you should take if you sustain a dog bite.

Why do dog bites happen?

Some dog bites happen by accident when people wrestle or play tug-of-war with their dog. But most of the time, dogs bite people as a reaction to feeling stressed, threatened, scared, or startled, according to the American Veterinary Medical Association (AVMA). More than half of dog bites occur in children, and they're far more likely to be seriously injured than adults.

"People don't always heed the behavioral signals that a dog is uncomfortable," says Dr. Christopher Baugh, associate professor of emergency medicine at Harvard Medical School. For example, some dogs are highly territorial and will bark, growl, snap, and lunge if outsiders enter their space — whether that's an apartment, yard, or crate. Or dogs may exhibit resource guarding, which shows up as anxious, aggressive behavior around food, toys, or beds.

"These situations can be high-risk, and children in particular have less awareness of that risk," says Dr. Baugh, who has children and two mixed-breed rescue dogs, Harley and Roxi.

What can you do to prevent dog bites?

Any dog — even a sweet, cuddly dog — can bite if provoked, according to the AVMA. Never leave young children alone with a dog without adult supervision. And teach children to never disturb a dog while it's eating, sleeping, or caring for puppies.

In a study of 321 facial dog bites treated at Harvard-affiliated Massachusetts General Hospital over a 20-year period, 88% of the bites were from known dogs. Most were in adults and occurred after playing with the dog, feeding the dog, and placing their face close to the dog. However, the hand (usually a person's dominant hand) is probably the most common location for a dog bite in an adult, says Dr. Baugh.

Other tips from the CDC to prevent dog bites include the following:

• Always ask a dog's owner if it's okay to pet their dog, even if the dog appears friendly.
• Make sure the dog sees and sniffs you before reaching out to pet it.
• Don't pet a dog that seems to be hiding, scared, sick, or angry.

What if an unfamiliar dog approaches you? Remain calm and still, avoiding eye contact with the dog. Stand with the side of your body facing the dog and say "no" or "go home" in firm, deep voice. Wait for the dog to retreat or move yourself slowly away.

What should you do if you're bitten by a dog?

Clean the wound with mild soap and running water, then cover it with a clean bandage or cloth. Some online resources recommend applying an antibiotic ointment or cream. But these products are recommended only for people with clear evidence of an infection, such as redness, pus, pain, swelling, or warmth, according to the American Academy of Dermatology.

If the injury is serious — with a bite on the face, heavy bleeding, or a possible broken bone — go to the emergency room. That's also a good idea if you're bitten by an unknown or stray dog, in the rare event that you might need medicines to prevent rabies (rabies post-exposure prophylaxis).

"Often, people are shocked after being bit and will understandably focus all their attention on their wound," says Dr. Baugh. The dog's owner may check in to see if you're okay, but then walk away. But you should get the person's contact information and make sure the dog is vaccinated against rabies, he says.

Keep in mind that:

• Emergency rooms are often crowded with long waits, so an urgent care clinic is a good option if the injury doesn't require immediate attention.
• Some wounds require stitches, ideally within 12 to 24 hours.
• The doctor may prescribe antibiotics to prevent possible infections, especially if you have health problems such as a weakened immune system or diabetes.
• You may also need a tetanus booster if you haven't had one in the past 10 years. If your vaccine history isn't available or you can't remember, you'll get a tetanus booster just in case.

What if a dog bite is less serious?

Let's say you have a less serious bite from a family dog known to have a current rabies vaccine. Bites that don't require stitches can be cleaned with mild soap and running water, then evaluated by your regular health care provider. They may tell you to simply monitor the wound for signs of infection.

"Doctors are trying to be more thoughtful about prescribing antibiotics and limit their use in low-risk situations, because overuse contributes to antibiotic resistance and exposes people to potential side effects without any benefit," says Dr. Baugh.