Choice of Primary Repair in Animal Bite Wound: A Novel Management Strategy

ABSTRACT

Animal bites, primarily from dogs and cats, pose a significant threat, especially to children. Wound infections are common complications caused by bacterial flora in the animal's mouth, making surgical debridement and delayed primary closure the standard treatment. However, recent studies reported no increased infection rates with primary closure compared to delayed closure after adequate debridement, particularly for facial wounds. Primary closure offers better cosmetic and functional outcomes. This study presents a case series to guide decision‐making on primary suturing versus leaving wounds exposed. Thirty patients with animal bites underwent surgery, including 23 dog bites and seven cat bites. Eight patients with deep facial lacerations from dog bites received immediate debridement and primary closure with epidermal and subcutaneous sutures. None developed infections, and the cosmetic results were excellent. In contrast, all seven cat bite wounds and nine infected dog bite wounds involved high‐risk factors, such as puncture wounds, hand injuries or diabetes. For high‐risk wounds, early debridement and leaving the wound open after initial treatment proved effective. Primary repair of facial dog bite injuries, even complex ones, is safe and yields good aesthetic outcomes. For high‐risk wounds, leaving them open after debridement is recommended to minimise infection risks.

Summary.

• Immediate debridement and primary closure of facial dog bite wounds are safe and provide excellent cosmetic outcomes.

• In contrast, cat bites and high‐risk wounds such as punctures, hand injuries, or those in patients with diabetes show high infection risks.

• For these cases, leaving wounds open after debridement with appropriate antibiotics is safer.

• A stratified approach‐primary repair for low‐risk facial injuries and conservative management for high‐risk wounds‐balances infection control with functional and aesthetic results.

1. Introduction

Animal bites are common and account for inevitable emergency department visits (about 1%–2%) [1, 2, 3]. Most cases are caused by dog bites (approximately 80%–90%), followed by cat bites (approximately 5%–15%). However, bites by other animals, including snakes, rabbits and rats, are much rarer [4]. Furthermore, most dog bite victims are children [3, 5].

In the United States, the incidence of animal bites is estimated to be 200 per 100 000 persons per year [6]. In 90% of dog bites, the victims of the animal bite are owners of the animals in over 90% of animal bite cases [6]. The epidemiological data of Taiwan on this topic are imprecise, as no nationwide statistics are precisely stored or reported. However, it is expected that with more pet dogs and pet cats raised in Taiwanese households, an unexpected incidence will be noted. Animal bites tended to occur during warmer seasons, which may be associated with animals becoming more offensive during the estrus cycle.

Wound infection is the most common complication of animal bites [4]. Patients with bites are exposed to a high risk of infection due to the bacterial flora in the mouth of the animal. Therefore, the most widely recommended treatment relies on surgical debridement and delayed closure [7]. The issue of the primary closure of animal bites remains controversial. However, in recent studies, after adequate debridement, there was no increase in the rate of primary closure compared with that of delayed closure, especially in the face [8]. Primary closures result in better cosmetic and functional outcomes [9]. Here, we present a case series for better decision‐making regarding whether primary suturing should be performed or the wound be left exposed in various situations.

2. Materials and Methods

We selected 30 well‐documented animal bite cases admitted to our hospital for surgery. Twenty‐three of them were patients with dog bites, and the remaining seven had cat bites. However, all the cat bite wounds were infected. Eight of the dog bite patients (including four children aged below 6 years and one older than 6 years) were attacked in the face with a significant deep laceration. All patients underwent immediate debridement and primary closure of the facial dog bite laceration. No infection was noted in these eight cases, and good cosmetic results were achieved. Details of the included patients are listed in Table 1.

TABLE 1.

Details of included patients.

Species	Wound location	Not infected	Infected
Dog bite (23)	Face	8	0
	Limb	6	5
	Hand	0	4
Cat bite (7)	Limb	0	3
	Hand	0	4

3. Results

3.1. Case 1

The first case was that of a 6‐year‐old girl weighing 18.5 kg who was attacked by her pet dog while staring at it over a short distance for a long time. The patient was admitted to our hospital and underwent surgery. Large amounts of normal saline were irrigated, and adequate debridement was performed. Primary suture closure was performed with subcutaneous 5‐O Vicryl and epidermal 6‐O nylon sutures (Figure 1A,B). The patient was admitted for another 7 days with advanced IV ceftriaxone 1 g QD (50 mg/kg/day) and clindamycin 185 mg Q8H (30/kg/day). The sutures were removed after retaining them for 7 days (Figure 1C). A fine appearance was noted at 2 months OPD follow‐up (Figure 1D).

FIGURE 1.

Clinical images of case 1 patient. (A) Before the operation, (B) after the operation, (C) seventh day after the operation with sutures removed and (D) at 2‐month OPD follow‐up.

3.2. Case 2

The second case involved a 65‐year‐old man who was attacked by his dog while sleeping on the same bed. This was a more severe case with a rupture of the lower eyelid and left nasolacrimal duct, in addition to a facial laceration. The patient was referred to our hospital and underwent the same debridement and primary closure strategy for the facial wound after the nasolacrimal duct was repaired by an ophthalmologist (Figure 2A,B). The patient was also admitted for another 7 days and treated with advanced IV betamycin (piperacillin 3 g + tazobactam 0.375 g) Q6H. Facial sutures were removed after retaining for 7 days (Figure 2C). A fine appearance was noted at 1‐month follow‐up at the OPD (Figure 2D).

FIGURE 2.

Clinical images of case 2 patient. (A) Before the operation, (B) after the operation, (C) seventh day after the operation with facial wound sutures removed and (D) at 1‐month OPD follow‐up.

3.3. Case 3

The third case involved a 50‐year‐old woman with atopic dermatitis who visited our OPD and had significant cellulitis and many small punctate wounds over her left lower leg (Figure 3A). The patient stated that she had been bitten by her pet dog 4 days prior. However, only a few trace tooth wounds with minimal bleeding were observed. Hence, she did not pay attention until the left lower leg had more swelling and erythema. The patient was admitted and underwent debridement and advanced intravenous tapimycin (piperacillin 4 g + tazobactam 0.5 g) Q6H. Despite adequate debridement of the deep puncture wound, extensive skin necrosis in the tooth trace area was still noted after 3 days (Figure 3B). The necrotic skin was debrided, and a betadine wet dressing was applied to the wound after adequate debridement. After another 7 days, wound infection was controlled, with no further skin necrosis or erythema around the wound (Figure 3C). The patient underwent artificial dermis implantation (Terudermis), and NPWT was applied (Figure 3D). The patient was discharged with progressive healing (Figure 3E) and a foam dressing (Aquacel Ag foam). A completely secondary healed wound was noted 1 month after the OPD follow‐up (Figure 3F).

FIGURE 3.

(A) Clinical image of the patient presented at our hospital after being bitten 3 days ago. (B) Skin necrosis with persistent erythema change around despite debridement 3 days ago. (C) 7 days after adequate debridement for the previous skin necrosis, (D) applied artificial dermis (Terudermis) and NPWT, (E) discharged after artificial dermis implantation for 7 days, (F) completely healed secondary wound at the 1‐month follow‐up.

3.4. Case 4

The fourth patient involved a 69‐year‐old man complicated with type II DM who visited the OPD for a poorly healing wound over his right lower leg induced by his home cat 1 month prior. Erythema changes around the four wound scabs were noted, which matched with the sharp four canine teeth of cats (Figure 4A–C). He reported that there were four miniature holes at the time of the bite, and the epidermis healed in less than 3 days. However, progressive swelling and erythema with a sensation of heat over the right lower leg were noted. The patient was admitted and debrided. Furthermore, wound reconstruction was performed using the STSG coverage. An IV antibiotic, Avelox 400 mg QD, was administered for 7 days before discharge (Figure 4D).

FIGURE 4.

(A) Illustration of four sharp canine teeth of a cat. (B and C) Cellulitis and skin necrosis over previously bitten right lower leg. (D) STSG reconstruction for puncture cat bite wound.

4. Discussion

Although dog bites are a frequent health problem, their management and choice of primary closure remain controversial. Dog‐bite wounds are often left exposed owing to the risk of infection if they are primarily closed. Previous studies indicated that despite thorough surgical debridement and irrigation of the wounds, the infection rate of a sutured dog bite wound was as high as 7.7% [10, 11, 12]. However, in recent studies, after debridement and use of prophylactic antibiotics, suturing of the dog bite wound did not increase the infection rate but achieved significantly better cosmetic results compared with the wound left open [9, 13]. Additionally, several factors influence the infection of a wound caused by an animal bite, including wound location, wound type, animal species, delayed treatment and patient type [1].

The location of the wound revealed a significant difference in the infection rate. The infection rates of animal bite wounds were as follows: face (4%–11%), leg (7%–15%), arm (17%–20%) and hand (18%–36%) [4, 6, 14]. The face has better circulation, whereas the hand has more tendons and bone tissues that are vulnerable to infection.

Many studies on facial dog‐bite wounds have advocated primary closure of the wound after being well debrided [15, 16, 17, 18]. In a large study, 600 individuals were randomly and evenly divided into two groups A and B. Subsequently, they underwent thorough debridement for dog bite facial lacerations without prophylactic antibiotic use. Group A left the wound open, and group B primarily closed the wound. Group A had an even higher infection rate (8.3%) than group B (6.3%), although the difference was not significant. Group B showed a significantly shorter healing time than group A. In a similar study, one case of infection from 143 bites was observed after primary closure and prophylaxis with intravenous amoxicillin and metronidazole for 5 days [19].

Paediatric facial dog bite injuries are an important issue as more pet dogs are staying together with children in Taiwan. Dog bite injury is one of the main causes of facial trauma in younger children [4]. The most common bite location in children was the head (62.1%), which decreased with older ages [20]. Dogs tend to attack the face when stared at for a long time. Additionally, children are too weak to protect their heads with their limbs.

Cat bite wounds are likely to become infected, though they are less traumatic and much smaller. Unlike dog bites, which cause laceration or avulsion wounds, cat bites are mostly small punctuated wounds owing to the four sharp canine teeth. These small opening wounds cause little bleeding, and the epidermis heals very soon. However, these wounds are easily overlooked by patients, and they do not go to the hospital in their early stages. However, bacteria on the sharp teeth of cats can easily infect deep soft tissue through deep inoculation wounds [3]. Furthermore, with little wound drainage, cat bite wounds are easily infected.

Pasteurella spp. are the most common organisms isolated from infected bite wounds in both dogs (50%) and cats (75%) [21]. Other organisms included streptococci (including S. pyogenes ) and staphylococci (including MRSA). In a study including 50 dog bite wounds and 57 cat bite wounds, mixed aerobic and anaerobic infections were found in 48% and 63% of dog bite and cat bite wounds, respectively. Only aerobic growth was observed in 42% of dog‐bite wounds and 32% of cat‐bite wounds. Common anaerobic organisms isolated from dog and cat bites include Fusobacterium, Bacteroides and Porphyromonas spp [22].

Wound cultures are ineffective for early or uninfected bite wounds. However, prophylactic antibiotic use following cat or dog bites reduces the risk of infection [23, 24, 25]. Empirical antibiotics against dog and cat bites should be targeted to combat Pasteurella, streptococci, staphylococci and anaerobes [26]. Clindamycin, macrolides, first‐generation cephalosporins and aminoglycosides are ineffective in the treatment of Pasteurella multocida , the most common pathogen after animal bite or scratch wound infections; hence, these should not be used alone [4, 27]. Aminopenicillin along with beta‐lactamase inhibitors (amoxicillin/clavulanate) is the first choice for dog‐ or cat‐bite wounds in adults and children [26]. For patients allergic to penicillin, a combination of cefuroxime/ceftriaxone or ciprofloxacin/levofloxacin with metronidazole or clindamycin is recommended [4, 28]. Additionally, monotherapy with moxifloxacin is feasible for simultaneous coverage of aerobic and anaerobic organisms [29, 30].

For all bite wounds, thorough early debridement is required, regardless of the wound size. For bite wounds on the face, primary closure or local flap reconstruction is proposed. Primary wound closure is feasible for easily cleanable wounds even in the limbs [31]. However, for wounds with high‐risk factors (such as a bite in the hand, cat bite, puncture wound, diabetes mellitus, or immunosuppression), wound opening may be a safer choice. The management strategy for animal bite wounds is summarised in Table 2.

TABLE 2.

Management strategy for animal bite wounds.

5. Conclusion

After debridement and proper antibiotic administration, the primary repair of facial dog‐bit injuries with epidermal and subcutaneous sutures, including complex soft tissue injuries, is safe. Good aesthetic outcomes may be achieved using this therapeutic approach. For animal bites on the limbs, especially those associated with high‐risk factors for infection such as punctuate wounds, diabetes mellitus, or cat bites, early debridement should be performed. Leaving a high‐risk wound exposed after the first debridement may be the proper treatment strategy.

Ethics Statement

This article was approved by IRB and no ethics related issues.

Conflicts of Interest

The authors declare no conflicts of interest.

Yu Y.‐S., Wang L.‐Y., Yang S.‐W., and Wang C.‐H., “Choice of Primary Repair in Animal Bite Wound: A Novel Management Strategy,” International Wound Journal 22, no. 9 (2025): e70761, 10.1111/iwj.70761.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.