The immediate aftermath of a dog bite often presents a counterintuitive medical decision: the wound is rarely closed with sutures. A dog bite wound is typically a combination of a crush injury, a laceration, or a deep puncture, all of which carry a substantial risk of infection. The standard medical protocol is to leave most of these wounds open, allowing them to heal naturally from the bottom up, a process known as healing by secondary intention. This practice is a deliberate strategy to prevent a minor injury from escalating into a severe, systemic infection.
Understanding the Bacteria in Dog Bites
The dog’s mouth contains a diverse and high concentration of bacteria that are normal flora for the animal but highly pathogenic to humans. When a dog bites, it injects these microorganisms deep into the tissue, creating a heavily contaminated wound. This contamination is the primary reason for the high infection rate, which can be as high as 10–20% for dog bites.
One of the most concerning bacteria is Pasteurella multocida, found in the oral cavity of up to 50% of dogs. Infections caused by P. multocida are notorious for their rapid onset, with symptoms like intense swelling, redness, and pain often appearing within 3 to 48 hours of the injury. Dog bite infections are typically polymicrobial, involving a combination of aerobic bacteria like Staphylococcus and Streptococcus species, as well as various anaerobic organisms.
How Closing the Wound Increases Danger
The primary rationale for avoiding immediate suturing, or primary closure, is the risk of sealing bacteria inside a contaminated wound. When a bite is closed, any remaining pathogens are trapped beneath the skin’s surface, preventing the wound from draining and effectively cleaning itself. This trapped environment quickly becomes a breeding ground for bacteria.
Crucially, suturing a deep, contaminated wound creates an anaerobic environment—one with low or no oxygen. Many of the dangerous bacteria introduced by the bite, particularly the anaerobic species like Bacteroides and Fusobacterium, thrive in these oxygen-deprived conditions. This proliferation can lead to a severe and rapidly progressing infection, such as an abscess or cellulitis, which requires more aggressive medical intervention.
Allowing the wound to remain open facilitates the continuous drainage of fluid, contaminants, and bacteria, disrupting the formation of an oxygen-poor space. This open management strategy dramatically reduces the concentration of bacteria and helps the body’s immune system fight the contamination effectively. While primary closure may offer a better cosmetic result, the increased risk of a deep-seated infection outweighs the potential benefit.
The Protocol for Open Wound Care
The initial management of a dog bite focuses entirely on meticulous decontamination and infection prevention. Treatment begins with generous and high-pressure irrigation of the wound, often using sterile saline solution, to mechanically remove foreign material and bacteria. A healthcare professional will also perform debridement, which involves carefully removing any visibly damaged or non-viable tissue to minimize the risk of bacterial growth.
In most high-risk cases, such as deep puncture wounds, bites to the hands or feet, or injuries in immunocompromised patients, prophylactic antibiotics are prescribed. The most common first-line oral antibiotic is amoxicillin-clavulanate, chosen because it is effective against both the aerobic bacteria, like Pasteurella, and the common anaerobes. The typical course of prophylactic antibiotics lasts for three to five days to prevent an infection from taking hold.
Most wounds are then dressed and left open to heal by secondary intention, forming granulation tissue from the base upward. An exception is made for wounds on the face, where cosmetic concerns are highest and the excellent blood supply lowers the infection risk. In these select cases, a doctor may opt for immediate primary closure or delayed primary closure, where the wound is thoroughly cleaned and observed for three to five days before being sutured. Close follow-up is always required, with patients reevaluated within 24 to 48 hours to monitor for developing signs of infection.