Bite wound treatment refresher

When a bite wound case comes into your practice, do your hackles rise like a cornered cat, or are you as calm as a golden retriever getting a belly rub?  

The details of a patient’s bite wound have a lot to do with how complicated the case is. There’s also a lot to keep in mind when treating patients with bite wounds. Looking back on the basics, understanding adjunctive treatments, and knowing when to refer are all key to making informed decisions in practice. 

The whole patient assessment 

Kristin Welch, DVM, DAVECC, is the founder of DVM STAT Consulting, a multi-specialty teleconsulting service for veterinary professionals. She said that a patient’s visible wound is often just the “tip of the iceberg” and that it is essential to conduct a whole patient assessment. This includes a comprehensive physical exam and an evaluation of the patient’s history and any comorbidities, all of which are essential to ensure that patients who present with bite wounds receive the most appropriate care.  

The type of trauma a patient sustains, for example, can give team members a lot of valuable information to guide their diagnostic plan. “Patients suffering from big-dog-little-dog trauma or cats involved in dog or other animal attacks often suffer from a combination of blunt and penetrating trauma,” Welch explained. Knowing that there is the potential for internal trauma can determine which additional types of diagnostic testing are indicated or what types of ongoing monitoring should be recommended.  

Other specific details of the bite wound that should be considered are the wound’s location, severity of tissue damage, and degree of contamination. The location of a wound can affect everything from how much tension will be applied to the wound, how much dead space will have to be addressed, and how much blood supply the wound will have to support its healing.  

The severity of tissue damage can be initially assessed by noting how much tissue is missing or not viable and if there is evidence of damaged blood supply that may lead to future necrosis. Wound contamination can be a helpful indicator of the likelihood of infection. It can also affect decisions regarding antibiotic use and wound closure.  

Apart from the details of the bite, Welch added, it’s important to consider factors such as the patient’s age, comorbidities, and medication history. A puppy, for example, may heal more quickly than a senior dog. A pet with an immune-mediated condition may not heal as well due to what Welch refers to as “abnormal inflammatory responses” or because of immunosuppressive medication they take for their condition. “Steroids impair fibroblast proliferation, macrophage activity, and collagen synthesis,” she said.  Knowing this information can help veterinary professionals decide on appropriate treatment options and how frequently to recheck a patient to ensure they are healing as expected.  

To close or not to close 

There are many factors to consider when determining if a bite wound should be treated by primary closure, delayed closure, or healing by second intention. These factors include not only the size and age of the wound, but also the hemodynamic status of the patient. Welch said that in some cases surgical wound closure may need to be delayed by 12 to 24 hours to allow for appropriate stabilization of a patient with life-threatening injuries.  

The amount of tissue damage, degree of wound contamination, and the location of the wound are also important to consider when determining if the wound will respond well to primary closure, if it will need significant debridement, and if it would be appropriate to place a surgical drain. In some cases, a decision may be made to delay closure to allow damaged tissue to declare itself as viable or not. 

There does not appear to be a firm consensus in the literature as to whether primary closure should only be attempted if a patient presents within the “golden period” of six to eight hours after sustaining their wound. This period was found in previous studies to be the amount of time required for enough bacterial contamination to result in infection.  

More recent studies in both animals and humans have determined that the time frame required for infection to set in can vary significantly based on the location of the wound, the immune status of the patient, the health of the blood supply, and many other factors. Welch advised, “a clean fresh wound can be closed primarily, after appropriate lavage, debridement, and assessment of the potential need for a drain.”  

Bandaging basics 

For wounds that will not be closed primarily, bandages can often be an important part of the treatment plan. Welch said that “the most significant change to bite wound management recommendations has been away from wet-to-dry bandages in wounds that are unable to be closed primarily and instead transitioning to moist wound healing.”  

Why? The removal of wet-to-dry bandages can cause significant pain to the pet and can also remove a significant number of epithelial cells, fibroblasts, and white blood cells that are important for wound healing. Moist bandages do not disrupt healing in this way and can enhance wound contraction, granulation tissue formation, and epithelialization, Welch said.  

As part of moist wound healing, honey—particularly Manuka honey—is frequently recommended for its antimicrobial properties and because it helps maintain moisture in dry or minimally effusive wounds. Welch cautions that honey should be used only during inflammatory and debridement phases of wound healing and should be discontinued once healthy granulation tissue is present.  

For wounds that are not dry or minimally effusive, honey is also likely not the best choice, Welch added. Other substrates to consider include calcium alginate (and other alginates) for highly effusive wounds, and hydrocolloids or hydrogel for minimally to moderately effusive wounds.  

Apart from the type of bandage applied, Welch emphasized the importance of appropriate bandage care and follow up. This may include sedation and analgesia for bandage changes, client education on proper bandage maintenance, and frequent bandage changes. According to Welch, no bandage should ever be left in place for more than 5 to 7 days without removing it to check the wound and skin around it.  

Antibiotics 

Because any open bite wound has the potential to become infected, antibiotics are frequently used in the treatment of bite wounds. In the age of antibiotic stewardship, it is appropriate to assess each bite wound carefully to determine whether topical and/or systemic antibiotic therapy is most appropriate. Topical antibiotics such as silver sulfadiazine are an excellent choice for partial thickness skin wounds and abrasions, especially if the wound is small and localized, Welch added. 

Wounds that are full-thickness, larger, or distributed throughout the body typically require systemic antibiotics. “For cases in which systemic antibiotics are indicated,” Welch explained, “initial antibiotic administration should be parenteral in nearly all cases.”  

She added that the most serious complications from infected bite wounds include systemic inflammatory response syndrome, sepsis, and multiple organ dysfunction, all of which can be more easily prevented or managed if antibiotic treatment is instituted as early as possible. She recommends starting with a broad-spectrum antibiotic such as a potentiated amoxicillin-clavulanate for empirical treatment and adjusting antibiotic therapy if needed based on culture and sensitivity results. 

Does every wound need to be cultured? Welch said it is “never wrong” to obtain a sample for culture, even if the plan is to hold on to it initially while monitoring wound progression.  

She offered some tips to help make wound cultures more informative: 

• Obtain culture samples after debridement and lavage instead of before. 

• Aim to collect samples from the deepest portion of the wound (even obtaining a sample of the tissue from the wound for culture) as opposed to the surface of the skin. 

• Remember that some negative culture results may be false negatives, and that antibiotic therapy may still be appropriate. 

When to refer 

While many bite wounds are amenable to treatment in general practice, there are a variety of scenarios in which it would be very appropriate to refer a bite wound case to a specialist (or to another facility) based on the practitioner’s comfort level, availability, and resources. 

Penetrative wounds of the thoracic or abdominal cavity necessitate thorough exploratory surgery. These cases also often need ongoing treatment for damage to internal tissue and organs. Comprehensive workup for these patients will often benefit from access to point of care ultrasound, radiographs, and/or contrast computed tomography.  

Both blunt and penetrative thoracic trauma can cause complications such as contusions, hemothorax, pneumothorax, and fractures that can require stabilization measures such as analgesics, oxygen therapy, chest tube placement, and ongoing in-hospital monitoring in some cases.  

Welch recommends that prior to referral, general practitioners take steps to initiate “analgesia, fluid therapy targeting hemodynamic stabilization, early parenteral antibiotic administration, and basic wound care.” This wound care should include clipping hair, lavage of the wound itself, and covering the wound with a temporary bandage to protect it from further contamination. Covering the wound is particularly important with penetrative thoracic wounds, which should be covered with an occlusive dressing to seal the wound and reduce the risk and severity of pneumothorax.  

Further reading:  

Wound management for veterinary technicians 

Photo credit: Marta Avanzi/iStock via Getty Images

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