Dog bites, even those that seem minor, carry a significant risk of bacterial infection. A dog’s mouth naturally harbors numerous types of bacteria, which are injected deep into the tissue when the skin is broken. Among the most concerning bacteria are Pasteurella multocida, which can cause rapid cellulitis, and Capnocytophaga canimorsus, a potentially fatal pathogen, especially for individuals with compromised immune systems. Other common culprits include various Staphylococcus and Streptococcus species. Vigilance for signs of infection is necessary from the moment the bite occurs, as symptoms can begin to manifest within 24 to 72 hours.
Immediate Wound Care
The first step after a dog bite is a thorough and immediate cleansing of the wound to mechanically remove bacteria and foreign debris as possible. You should wash the wound under warm, running water using mild soap for five to ten minutes. This process helps flush out pathogens from the deeper layers of the injury, which is especially important for puncture wounds that do not bleed freely.
After the initial washing, gently pat the area dry with a clean cloth, and then apply an over-the-counter antibiotic ointment to the injury site. Covering the wound with a sterile, non-stick bandage protects the area from further contamination and supports the healing process. While these first aid measures reduce the chance of infection, careful monitoring remains necessary because bacteria may have been driven deep into the tissue.
Localized Indicators of Infection
The earliest signs of a developing infection appear directly at the wound site, often within the first three days after the bite. One of the most noticeable indicators is an increase in redness (erythema) that begins to spread outward from the edges of the injury. While some mild redness is a normal inflammatory response to trauma, a spreading or intensely red area suggests that the bacteria are multiplying in the surrounding skin.
An infection is likely if the pain at the site intensifies instead of slowly subsiding over the first 24 hours. A throbbing or escalating discomfort is a clear warning sign that the body is fighting a growing bacterial presence. Increased swelling (edema) is another localized indicator, particularly if the puffiness feels tight or hard to the touch and continues to worsen over time.
The area around the bite may also begin to feel noticeably warm to the touch, with heat radiating from the wound site. This warmth is a result of increased blood flow to the infected area as the immune system attempts to deliver defensive cells. The clearest visual sign of a localized infection is the presence of discharge or pus, which may appear thick, opaque, and colored yellow, green, or gray. This material signals a clear bacterial invasion that requires medical assessment. A final indicator is a delay in the wound’s healing or if the edges begin to reopen after initially closing.
Systemic Warning Signs Requiring Emergency Care
When an infection moves beyond the initial injury site, it becomes a systemic issue, meaning it affects the entire body and requires immediate emergency medical attention. The clearest sign of a spreading infection is the onset of a fever, typically defined as a body temperature above 101°F (38.3°C). Fever indicates that the body’s central thermostat is resetting to create an environment hostile to the multiplying bacteria. The fever is often accompanied by chills or uncontrollable shivering.
Another serious sign is the appearance of red streaks (lymphangitis) that extend away from the bite wound toward the torso. This shows that bacteria have entered the lymphatic system, indicating a rapidly spreading infection that can lead to sepsis. You should also check the lymph nodes located closest to the bite, such as those in the armpit or groin. Swollen, tender lymph nodes indicate that the body’s immune filtering system is actively trapping and fighting the traveling bacteria.
A systemic infection can cause general symptoms like weakness, fatigue, nausea, or vomiting. These signs suggest the infection is heavily taxing the body’s resources. A spreading infection can also lead to more severe neurological symptoms, such as confusion, dizziness, or a rapid heart rate. If the bite is on a limb, the infection may compromise circulation or nerve function, resulting in a loss of sensation or inability to move the affected digits. Any systemic warning sign warrants an immediate trip to the emergency room for diagnosis and prompt administration of appropriate antibiotics.