Bite Mark on Boy’s Arm: Child Abuse-or Mimic?


This 4-year-old boy returned home after a day at a small private daycare with a bite mark on his forearm.

This 4-year-old boy returned home after a day at a small private daycare with a bite mark on his forearm. The mother stated that she had picked the child up after work and the two had eaten dinner together. Shortly after dinner she prepared a bath for him while she did something in the house. She reentered the bathroom to wash the child and found the bite mark. The mother asked the child about the source of the bite, but he did not give any answers.

The mother called the daycare owner for more information. The owner told the mother that she and 3 other preschoolers were at the daycare all day alone; it was unclear whether the owner had seen or known about the bite, but she had not reported it. The mother was angered by owner’s apparent lack of concern and sought a medical opinion and called the local police.

The investigating officer was concerned about the daycare because of previous complaints concerning “other injuries.” The child was examined by a physician at the officer’s request. The child made no disclosure to the officer or physician.

Physical examination revealed no other injuries.

Is this bite the mark of physical abuse-or is there another possible explanation?

Click here for answer and discussion.

Answer: The perpetrator was never identified

In most cases of physical abuse, there is little chance of identifying the perpetrator short of an eyewitness or an exact timeline. This is not the case with bites, which offer the potential to reveal the identity of the perpetrator beyond a reasonable doubt.

When you see a bite mark
The first step is to determine whether a lesion is actually a bite. Diagnostic considerations include burns, dermatologic conditions, and animal versus human bites, as well as pattern bruising, like that caused by such sources as a shoe heel.

A human bite imparts more of a crushing injury than a dog or cat bite, which involves a tearing action. Animal bites also have a more distinctive canine tooth pattern. Human bites are circular: the pattern is formed by two “U”-shaped arches with a clear section in the middle. The measurement of the injury is also diagnostic. Adult human bites have an inter-canine measurement of 3 to 4.5 cm; for a small adult or child, this measurement is approximately 2.5 to 3.0 cm and in children with deciduous teeth, it is less than 2.5 cm. These figures come from the dental literature and have not been validated in abuse research. They are used as a range of size for an initial investigation.

The examining physician should first determine whether the lesion is a bite. The second consideration is whether a DNA swab is indicated.  Evidence may be present for an undetermined period if it is dry and undisturbed. Any available DNA evidence has the potential to positively identify the perpetrator; its collection usually takes please in the ED or abuse center if the injury is fresh.

Photographs should be taken to document the injury. They should be taken in two different planes, with a color/size standard used for later evaluation.

After photographing and collecting evidence, the wound needs to be cleaned to remove any bacteria that could have been transferred at the time of the injury. Appropriate antibiotic coverage should be prescribed based on CDC recommendations. There are reports of transmission of viral infections, such as hepatitis, after bites and concerns about viral infections need to be considered on a case-by-case basis.

When there are questions regarding the injury or the quality or orientation of the photographs, the bite victim should be referred to a dentist who will look for dental clues in the wound that may suggest the perpetrator. If the dentist has additional concerns or questions, he or she may recommend consultation with a forensic dentist. The forensic dentist may be able to get better pictures using specialized photography techniques and equipment to further identify the perpetrator. Either of these professionals should be consulted as soon as possible before the evidence becomes further compromised. 
Outcome of this case
This case did not end with a satisfying conclusion. The child did not reveal his perpetrator. The bite was measured and appeared to be that of a large child or adult. The bathing had washed away any DNA evidence that might have proved who the perpetrator was and the police were therefore not interested in pursuing the case any further. The police recommended that the mother take the child to a different daycare and the case was closed.

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