Figure 1A.Seven-year-old boywith a dog bite on his face.

Figure 1B.Thirteen-year-old girlwith adog bite on her face.

Figure 1CSixteen-year-old boy with a dog bite on his palm. 

Bite injuries are a significant problem in the United States. Discriminating between human and animal bites and identifying those associated with child maltreatment is essential. Approximately 250,000 human bites and several million animal bites occur annually.¹ There was also a reported increase in animal bite injuries during the COVID-19 pandemic.² Despite their frequency, it can be challenging to distinguish between types of bites. There are also few detailed images and descriptions of cutaneous findings of human and animal bites in the literature.

Additionally, though such injuries occur in various ways, pediatric providers must consider the possibility of child maltreatment. In the COVID-19 pandemic, there was also a documented increase in child abuse–related injuries.³ Though bite wounds are a less common cutaneous finding in child abuse,⁴ both human and animal bites may result from nonaccidental trauma or neglect. In this paper, we provide several cases of human bite injuries, juxtaposed with cases of bite injuries from common animals. This was prompted by the increases in child abuse and animal bite injuries during the COVID-19 pandemic, with the need to add to the limited descriptions of cutaneous findings of bites in the literature.

Animal bites

The most common causes of animal bites are dogs and cats. Several features help distinguish their bites from those caused by humans. Most bites are from pets and can be prevented through provider emphasis on pet safety.¹

Dog bites

Dogs are the most common cause of bites in children,⁵ with peak incidence at aged 5 to 9 years and more commonly affecting boys.¹ Rates vary by study, but approximately 20% of dog bites in children become infected.¹ Dog bites result in tissue tearing with superficial skin trauma, referred to by some authors as “hole-and-tear” injuries.^6,7 Upper and lower limbs, followed by the face, are the most frequent sites affected.^6,7 Dogs can exert considerable pressure while biting and can cause serious morbidity and mortality, particularly in young children and infants.⁸ The following cases demonstrate common presentations of dog bites:

• Figure 1A shows a 7-year-old male with a bite wound to the face. We can appreciate extensive bleeding and hole-and-tear injuries to both the upper and lower lip. Such hole-and-tear injuries are a classic pattern of injury from dog bites.
• Figure 1B shows a 13-year-old female, also with a bite wound to the face. There are slightly arcuate, narrow crusts on the medial aspect of the left lower lid extending from the lower aspect of the medial canthus and on the left nasal rim. There is an additional minimal crust on the underside of the nasal orifice.
• In Figure 1C, there is a dog bite on the palm of a 16-year-old male with a history of eczema. There are purpuric lesions from the dog bite mark. This figure shows a clear outline of the bite marks.

Cat bites

Figure 2A. Child with acat bite on the forearm, after 24hours.

Figure 2B.Woman with a cat bite.

​​Cat bites are also a significant problem in the United States, causing approximately 66,000 emergency department visits each year.⁵ There is no predisposition for a certain age group in the pediatric population, though they more often affect girls.¹ Compared with dog bites, they are more likely to be provoked through mishandling of the animal and are characterized by small, deep puncture wounds.^9,10 These may seem less severe, but they are more difficult to clean, resulting in an increased infection rate compared with dog or human bites.¹ ​The following cases demonstrate common presentations of cat bites:​​

• In Figure 2A, there are deep puncture wounds to the forearm of a young child, suggestive of a cat bite. There is significant bruising along the periphery of each puncture wound, and the skin has an erythematous appearance. This image was taken 24 hours after the injury.
• ​​In Figure 2B, we see similar cat bite marks on the mother of the patient from Figure 2A. There are three puncture wounds with significant bruising along the periphery of each. In this case, the diagnosis was clear because the mother and child had similar bites and there was a new kitten in the home. This case highlights the importance of a thorough history to correctly identify the cause of bites.

Human bites

Human bites are less common than animal bites, with approximately 10% of such wounds in children becoming infected.¹¹ They typically appear as circular, semicircular, or ovoid and may be accompanied by abrasions, lacerations, and punctures. In a study of human bites in children, 75% were superficial abrasions, 11% were lacerations, and 13% were puncture wounds.¹² Of these, 42% involved an upper extremity and 33% involved the face or neck.¹² Most human bites in children are superficial and antibiotic prophylaxis is not recommended unless the wound is deep, involving the hand, or not cleaned quickly due to delayed presentation to a provider.^11,12

Some human bite injuries are sustained, both intentionally and unintentionally, secondary to physical altercations, recreational drug use, or sexual activity. Sexual activity in particular should be broached when relevant, but in a careful manner. Speaking in private can alleviate embarrassment of discussing consensual sex and provide a safe space to reveal anything nonconsensual. Physical altercations are more common, and many childhood bite injuries result from fighting or playing with other children.^11,12

Though rare, several conditions are associated with self-inflicted biting. In one study, 6% of bite injuries were self-inflicted.¹¹ For example, self-mutilative behavior is common in Lesch-Nyhan syndrome. These behaviors commonly begin around aged 1 year, and many individuals will bite or chew on their fingers, sometimes down to the bone.^13,14 Other conditions that can result in self-inflicted bite wounds include congenital insensitivity to pain and developmental disorders.

Any circular or oval bite marks, regardless of stated circumstance, should prompt significant workup. Traditionally, the distance between maxillary canine teeth has been used to help differentiate bites inflicted by an adult or child.¹³ This includes intercanine distance ranges of more than 3.0 cm for adults, 2.5 to 3.0 cm for children, and less than 2.5 cm for younger children and toddlers.¹³ While useful for an initial estimate, such measurements are inaccurate due to significant overlap in jaw sizes by age. Still, a larger distance may warrant more detailed measurements and photographs, or direct referral to a forensic odontologist for further workup. Additional signs of nonaccidental bite injuries include more significant damage, wounds at various stages of healing, and presence on body parts hidden by clothing (thorax, groin, etc). When clinical suspicion is suggested, and if available, it can be prudent for providers to swab bite marks and perform DNA testing.

​The following cases demonstrate common presentations of human bites:

Figure 3A. Four-month-old infant with an adult human bite on the leg.

Figure 3B.Four-month-old infant from Figure 3A with a 5 x 3-cm adult human bite on the thigh.

Figure 3C.Four-month-old infant with an adult human bite on the thigh.

• Figures 3A and 3B demonstrate adult human bite marks on a 4-month-old infant. There is significant bruising and a circular or oval bite mark with no puncture wounds. The measured size of the bite wound in Figure 3B is rather large and is thus considerably suggestive of an adult human source.
• Figure 3C shows the outline of a circular bite mark on the thigh of another 4-month-old infant. The circular area of darker pigmentation can be used to estimate the size of the bite. The father claimed this occurred while playing and that the baby never cried.

Figures 3A, 3B, and 3C clearly demonstrate the superficial marks common in human bite injuries. This compresses the tissue and results in bruising and postinflammatory hyperpigmentation, particularly in individuals with darker skin tones.³

Discussion

It is important for pediatric providers to differentiate human and animal bites and identify the context in which they occur. The character of injury can be helpful to determine its cause. Animal bites tear tissue and flesh, whereas human bites result in superficial bruising. Dogs often cause “hole-and-tear injuries”^6,7 while cats cause deep puncture wounds.¹ Human bites are more circular and most (approximately 75%) are superficial.¹² The location of injury is less useful in determining a source, as those from both animals and humans most commonly affect the extremities and face.^1,12 Recognition of these details is key to providing the highest standard of care for these patients.

The mainstay of bite wound treatment is cleaning and (when necessary) closure to prevent subsequent infection.^1,15 Prophylactic antibiotics are not often needed, but context is important. For example, hand and puncture wounds are more likely to become infected than facial and superficial or laceration wounds.¹ Approximately 20% of dog bites become infected and, though they often seem less severe, cat bites have an infection rate of around 50% due to their deep penetration.¹ When clinical suspicion indicates, or for wounds with signs of active infection such as purulent discharge or cellulitis, a course of broad-spectrum antibiotics should be given that cover oral flora of the bite source and common skin flora. Clinical decision-making flowcharts can assist with regimens, but an oral β-lactam plus β-lactamase inhibitor is commonly used.^1,15 Finally, source identification guides other recommended courses of action, such as prophylaxis for rabies and possibly euthanizing the causational animal.^1,15 Emphasis on pet safety is vital for primary prevention of most bites.¹

Whenever there is a circular bite mark on a child suggestive of a human source, nonaccidental trauma must be considered.⁴ Although the distance between teeth can help differentiate between child and adult bites,¹³ the most effective strategy is thorough history and physical examination, including documentation and photography of the injuries. It is important to document recent fights or rough play with the patient and other children¹² and inquire about self-harming behaviors. Providers should be aware of the aforementioned conditions associated with self-inflicted bite wounds. Parental observation and assessment of developmental milestones can indicate delay, and a complete neurological exam should reveal a lack of response to pinprick testing or the motor symptoms characteristic of Lesch-Nyhan syndrome.¹⁴ Bite wounds in areas a child cannot reach with their mouth is a clear red flag, and wounds hidden by clothing or causing significant damage are also of concern. When the context of a human bite is suspicious, pediatric providers are responsible for raising concern of child abuse/neglect through prompt contacting of Child Protective Services. If indicated, a consult to a child abuse specialist and/or forensic odontologist may be helpful, as is DNA testing when available.

With regard to cases 3A, 3B, and 3C, the children were thoroughly evaluated for possible child maltreatment and none were found to have been in an abusive relationship. Parents were the source of all of these bites, and the settings were determined to be innocent. Notably, all of the wounds were in common locations (the extremities) and clearly visible areas. There was minimal damage to the skin, with bruising but no puncture wounds. The extensive history from both providers and Child Protective Services was consistent, and patient education was provided to avoid future such incidents.

Conclusion

When assessing a bite wound, a thorough history and ​full body ​physical examination is essential. Providers should closely examine wounds and describe them accurately and completely while paying close attention to any punctures, abrasions, lacerations, bruising, and other markings. This is key for clinical decision-making and identification of findings concerning child maltreatment. In such circumstances, detailed documentation, including photographs and (if appropriate and available) DNA testing, prompt reporting to Child Protective Services, and referral to child abuse experts is crucial to the well-being of the affected child.

During the COVID-19 pandemic, separate studies found increases in general child abuse and animal bite injuries.^2,3 This is most likely due to school closures and increased virtual work, which resulted in more time and stress in the home environment.^2,3 Though it is undetermined if there may be a relationship between these 2 findings, it raises important questions for pediatric providers. Bite injuries are already common, so knowledge of their presentation and treatment is vital. The cases provided will hopefully serve to improve management of such injuries and recognition of child maltreatment.

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