Dog bites are common injuries that carry a significant risk of infection, even when the wound appears minor. A dog’s mouth harbors a diverse array of bacteria, including species like Pasteurella multocida, Staphylococcus, and Capnocytophaga canimorsus, which can be driven deep into the tissue when the skin is broken. These microorganisms can rapidly multiply, turning a simple injury into a serious health concern. Monitoring the bite site closely in the hours and days following the incident is necessary, as the initial trauma can mask the onset of infection. Recognizing the specific signals of infection is the first step toward effective management and recovery.
Local and Visible Warning Signs
Initial redness and swelling are expected as part of the body’s natural inflammatory response. A localized infection is signaled when pain worsens rather than gradually improving after the first 24 hours. The discomfort may evolve into a persistent, throbbing sensation, indicating that bacteria are actively multiplying within the tissue.
Spreading redness, known as erythema, indicates the infection is advancing. While minor redness around the bite is normal, an expanding area of pink or red skin suggests bacteria are colonizing surrounding tissue. This is often accompanied by increased heat radiating from the site, making the area feel distinctly warm or hot.
The skin’s texture and appearance also change when infection is present. Significant swelling that makes the area feel firm or hard, called induration, means fluid and inflammatory cells are building up beneath the surface. This hardness indicates the infection is affecting the deeper layers of skin and soft tissue.
The most obvious sign of a localized infection is abnormal wound discharge. An infected site often oozes pus, a collection of dead white blood cells, bacteria, and tissue debris. This discharge can appear cloudy, yellow, or greenish in color and may be accompanied by a foul odor.
Systemic Symptoms of Spreading Infection
When an infection moves beyond the immediate wound site, it triggers a broader immune response, leading to systemic symptoms. The development of a fever indicates the body is fighting the invading bacteria. A temperature rising above 100.4°F (38°C) signals the infection has become generalized and requires urgent medical attention.
The immune response can also manifest as chills, shaking, or night sweats, which are the body’s attempts to regulate temperature. A general feeling of malaise, fatigue, or being unwell often occurs. This pervasive sickness is more pronounced than simple tiredness after an injury and suggests the infection is consuming significant bodily resources.
A specific and concerning sign is red streaking, medically termed lymphangitis, extending away from the wound toward the nearest lymph nodes. These streaks follow the lymphatic vessels, which bacteria use to spread the infection. If the infection has traveled this far, the lymph nodes closest to the bite—such as those in the neck, armpit, or groin—will often become noticeably swollen and tender.
Prompt Medical Intervention and Treatment
Any sign of a localized infection, such as worsening pain, spreading redness, or pus, should prompt a visit to a healthcare provider, typically within 24 hours. Systemic symptoms like fever, chills, or red streaking require immediate or emergency medical care. Delaying treatment for a spreading infection increases the risk of severe complications, such as cellulitis or sepsis.
A medical professional will thoroughly clean and irrigate the wound with sterile solutions to remove bacteria and foreign debris. They will assess the depth of the injury and may take a wound culture to identify the specific bacteria causing the infection, especially if the bite is severe. Deeper wounds may also require assessment for damage to underlying structures, such as tendons or joints.
Treatment involves the administration of antibiotics, often started immediately before culture results are available. The first-line choice is commonly amoxicillin-clavulanate, a combination medication effective against the diverse bacteria found in a dog’s mouth. If an infection is present, the course is typically ten days or longer, and the patient must complete the entire course as prescribed, even if symptoms improve quickly.
The healthcare provider will also evaluate the patient’s tetanus immunization status. If the last booster was more than five years ago or the history is unknown, a booster shot will be administered to prevent this serious bacterial disease. Prompt medical care helps prevent deeper complications like abscess formation, bone infection (osteomyelitis), or nerve damage.