A dog bite can give you anything from a minor skin wound to a life-threatening infection, depending on the depth of the bite, where it lands on your body, and how quickly you clean and treat it. Most dog bites cause some combination of physical tissue damage and bacterial contamination, and roughly 10 to 20 percent of bites become clinically infected. Beyond infection, dog bites carry risks of rabies, tetanus, nerve damage, scarring, and lasting psychological effects.
Physical Injuries From the Bite Itself
A dog’s jaws produce enormous crushing force. Unlike a clean cut from a knife, a dog bite creates a messy combination of puncture wounds, torn tissue, and crush injuries. The teeth puncture skin and push bacteria deep into tissue, while the jaw pressure can macerate (shred) soft tissue underneath. In severe attacks, dog bites cause tissue avulsion, where chunks of skin or muscle are ripped away entirely. Fractures are possible too, especially in small bones like fingers or in children’s facial bones.
Puncture wounds are particularly deceptive. They may look small on the surface but can drive bacteria deep into muscle, tendons, or joint spaces where infection thrives. Bites to the hand and wrist are especially prone to complications because tendons, joints, and bones sit just beneath the skin with relatively little protective tissue.
Bacterial Infections
Dog saliva contains dozens of bacterial species that can cause infection in humans. The most common culprits include Pasteurella (found in the majority of infected dog bite wounds), Staphylococcus aureus, Streptococcus species, and various gut-related bacteria. When a dog’s teeth break the skin, these organisms get pushed directly into your tissue.
Signs of infection typically appear within 24 to 72 hours: increasing redness, swelling, warmth, throbbing pain, and pus draining from the wound. Pasteurella infections tend to develop fast, sometimes within 12 hours of the bite, with rapid swelling and redness around the wound site. Left untreated, a localized infection can spread into deeper tissues, causing abscesses, joint infections, or bone infections (particularly in hand and finger bites).
Certain bite types carry higher infection risk and typically warrant preventive antibiotics:
- Puncture wounds that are difficult to clean thoroughly
- Bites to the hand, wrist, or genitals
- Crush injuries with damaged, devitalized tissue
- Wounds that have been stitched closed
People with diabetes, weakened immune systems, liver disease, rheumatoid arthritis, or those who have had their spleen removed face significantly higher risk of serious infection from any dog bite.
Capnocytophaga: A Rare but Dangerous Infection
One bacterium deserves special attention. Capnocytophaga canimorsus lives in the mouths of healthy dogs and is harmless to them, but in certain people it can cause a rapidly fatal infection. Symptoms start with fever, diarrhea, vomiting, headache, and blisters around the bite area, then can progress to sepsis (a bodywide immune response to infection), heart inflammation, kidney failure, and gangrene. Some survivors lose fingers, toes, or limbs to amputation.
People without a functioning spleen face 30 to 60 times the normal risk of dying from Capnocytophaga. In these high-risk individuals, the infection can progress from mild symptoms to organ failure and death within 24 to 72 hours. While Capnocytophaga infection is uncommon in healthy adults, it’s one reason even minor dog bites in immunocompromised people are taken seriously.
Rabies
Rabies is the most feared viral risk from a dog bite. Once symptoms appear, rabies is nearly 100 percent fatal. In the United States, domestic dogs are rarely rabid thanks to widespread vaccination, but the risk is real with stray, unvaccinated, or wild-acting dogs, and it’s a major concern in many other countries.
If there’s any possibility the dog was rabid, post-exposure treatment involves a series of four vaccine injections given over two weeks (on days 0, 3, 7, and 14), plus an additional injection of rabies immune globulin at the start to provide immediate protection while your body builds its own response. People with weakened immune systems receive a fifth vaccine dose on day 28. This treatment is extremely effective when started promptly, but the window matters. If you’re bitten by an unknown dog, a stray, or a dog behaving strangely, getting evaluated quickly is critical.
Tetanus
Dog bites are classified as “dirty or major wounds” for tetanus purposes because saliva, along with any soil or debris, contaminates the wound. If you’ve completed your primary tetanus vaccine series and your last booster was less than five years ago, you’re generally protected. If your last tetanus shot was five or more years ago, you’ll likely need a booster within 48 hours of the bite. People with unknown vaccination history, incomplete vaccination, or severe immune deficiency may also need tetanus immune globulin for immediate protection.
Sepsis: When Infection Spreads
The most dangerous turn a dog bite infection can take is spreading from the wound into the bloodstream. Sepsis can develop from any of the bacteria introduced by a bite, not just Capnocytophaga. Warning signs that a bite infection has become systemic include high fever, confusion, rapid heart rate, muscle and joint pain far from the bite, and feeling extremely unwell. The progression from a localized wound infection to sepsis can happen quickly, sometimes within days. Sepsis can lead to organ failure and is a medical emergency.
Scarring and Nerve Damage
Because dog bites tear and crush tissue rather than cutting it cleanly, they tend to heal with more noticeable scars than surgical wounds. Facial bites, which are common in children, can cause permanent disfigurement. Deep bites can sever nerves, leading to numbness or loss of function in the affected area. Tendon damage, particularly in the hands, may require surgical repair and months of rehabilitation to regain full movement.
Psychological Effects
The mental health consequences of dog bites are real and frequently overlooked. Common psychological outcomes include post-traumatic stress disorder (PTSD), intense fear of dogs, nightmares, anxiety, and avoidance behaviors. Children are especially vulnerable. In studies of child bite victims, over half developed symptoms consistent with PTSD. One study found that 38 out of 358 patients developed acute stress disorder shortly after the bite, which is an early indicator that PTSD may follow. These symptoms can appear within days and persist for months or years without treatment.
Even adults who consider themselves “fine” after a bite may notice they cross the street to avoid dogs, feel their heart race when they hear barking, or have intrusive memories of the attack. These are normal trauma responses, and they’re treatable with the same approaches used for other forms of PTSD.
Immediate Steps After a Dog Bite
What you do in the first few minutes matters. If the wound is bleeding heavily, apply firm pressure with a clean cloth. Once bleeding is controlled, wash the wound thoroughly with soap and running water for at least five minutes. This simple step significantly reduces bacterial load in the wound. Cover it with a clean bandage.
Try to identify the dog and determine its vaccination status if possible. This information will help medical professionals decide whether you need rabies prevention, and it allows the dog to be observed for signs of illness. Any bite that breaks the skin, any bite to the hand or face, any deep puncture wound, and any bite from an unknown or unvaccinated dog warrants prompt medical evaluation.