ABSTRACT OF THE WEEK

Journal of forensic sciences

Characterization and Comparison of Injuries Caused by Accidental and Non-accidental Blunt Force Trauma in Dogs and Cats.

J Forensic Sci. July 2016;61(4):993-9.

Nida P Intarapanich¹, Emily C McCobb², Robert W Reisman³, Elizabeth A Rozanski⁴, Pichai P Intarapanich⁵

¹ Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536.; ² Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536.; ³ Forensic Sciences, American Society for the Prevention of Cruelty to Animals, 520 8th Avenue, New York, NY, 10018.; ⁴ Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536.; ⁵ Department of Mathematics, Southern Connecticut State University, New Haven, CT, 06515.

Abstract

Motor vehicle accidents (MVA) are often difficult to distinguish from non-accidental injury (NAI). This retrospective case-control study compared animals with known MVA trauma against those with known NAI. Medical records of 426 dogs and cats treated after MVA and 50 after NAI were evaluated. Injuries significantly associated with MVA were pelvic fractures, pneumothorax, pulmonary contusion, abrasions, and degloving wounds. Injuries associated with NAI were fractures of the skull, teeth, vertebrae, and ribs, scleral hemorrhage, damage to claws, and evidence of older fractures. Odds ratios are reported for these injuries. MVA rib fractures were found to occur in clusters on one side of the body, with cranial ribs more likely to fracture, while NAI rib fractures were found to occur bilaterally with no cranial-caudal pattern. Establishing evidence-based patterns of injury may help clinicians differentiate causes of trauma and may aid in the documentation and prosecution of animal abuse.

Companion Notes

Retrospective, case controlled study comparing injuries caused by accidental (hit by car) and non-accidental blunt force trauma in dogs and cats

Introduction on animal abuse

- considerable research shows a correlation between the following:

- animal abuse

- criminal behavior

- family violence

- suspicious behavior in clients and animals that may indicate animal abuse

- inconsistent or discrepant history

- previous injuries or deaths in other animals in same household

- particularly if unexplained

- repetitive injuries

- defensive or unconcerned behavior of the owner

- abnormal behavior by animal, such as fear

- in a veterinary forensic science textbook

- the following, in particular, are difficult to differentiate from each other

- motor vehicle accidents (MVA)

- non-accidental injury (NAI)

- differentiation is difficult due to lack of data on injuries known due to physical abuse

- differential diagnosis for animals presenting with skeletal injuries

- skeletal disorders

- osteogenesis imperfecta

- metabolic bone disease

- motor vehicle accidents

- most common injuries in a study of 239 cases of MVA in dogs

- long bone fractures

- pulmonary injury

- pelvic fractures

- hemoabdomen

- soft tissue injury

- in a study of 600 dogs involved in MVA

- superficial soft tissue abrasions and lacerations

- at the extremities of 79% of dogs

- at the head, 35%

- skeletal injuries, 59.5%

- 89.6% were caudal to the last thoracic rib

- skull fractures, 6%

- fractured ribs, 3%

- NAI

- in a study of UK veterinarians surveyed about NAI

- in 147 suspected cases of NAI in dogs that could be misattributed to MVA

- 1 pelvic fracture, 0.7%

- 21 cases with skull fractures, 14.3%

- 23 cases with fractured ribs, 15.6%

Study design

- study population: animals seen at Tufts University

- 426 dogs and cats treated after MVA (47 cats, 379 dogs)

- exclusion criteria:

- no physical examination and 2-view thoracic radiography

(including animals dead on arrival or euthanized after physical exam)

- 1035 cases excluded because radiographs were not available

- medical record search initially found 1622 cases

- accident occurred more than 7 days before presentation

- history of a prior MVA

- other causes of trauma suspected

- 50 dogs and cats treated after NAI (19 cats, 31 dogs)

- legal cases at Humane Law Enforcement Division of ASPCA

- arrest warrant issued

- procedure: records from 01/01/09-06/30/13 retrospectively reviewed

Results

- injuries significantly associated with MVA

- pelvic/sacral fractures; Odds ratio (OR) in favor of NAI: 0.3:1

- pneumothorax; OR in favor of NAI: 0.16:1

- pulmonary contusion; OR in favor of NAI: 0.41:1

- abrasions; OR in favor of NAI: 0.041:1

- degloving wounds; OR in favor of NAI: 0.11:1

- injuries associated with NAI

- evidence of older fractures; OR in favor of NAI: 120:1

- fractures of the following:

- skull; Odds ratio (OR) in favor of NAI: 15:1

- teeth; OR in favor of NAI: 7:1

- vertebrae; OR in favor of NAI: 3:1

- ribs; OR in favor of NAI: 4:1

- scleral hemorrhage; OR in favor of NAI: 4.5:1

- damage to claws; OR in favor of NAI: 3:1

- differences in rib fractures between MVA and NAI cases

- MVA rib fractures occurred in clusters on one side of the body

- cranial ribs more likely to fracture

- ribs 1-4 most likely to fracture, followed by ribs 4-7

- then 7-10 and finally 11-13

- 92.1% had fractures on 1 side of the body

- NAI rib fractures occurred bilaterally

- no cranial-caudal pattern found

- 64.3% had fractures on 1 side of the body

- significantly more likely to have rib fractures on both sides of the body

- history & signalment

- most common breeds in MVA cases

- Labrador retriever, 10.3%

- domestic short hair cat, 8.2%

- Labrador retriever mixes, 5.6%

- golden retriever, 4.5%

- German shepherds dog, 3.1%

- most common breeds in NAI cases

- domestic short hair cat, 32%

- pit bull, 18%

- chihuahua, 10%

- Yorkshire terrier, 6%

- median age for dogs in MVA cases: 3 years

- median age for dogs in NAI cases: 1.5 years

- significantly younger than dogs involved in MVA

- median age for cats in MVA cases: 3.2 years

- mean age for cats in NAI cases: 1 year (significantly younger)

- median weight for dogs in MVA cases: 21.6 kg

- median weight for in NAI cases: 5.6 kg

- dogs involved in NAI weighed significantly less than dogs involved in MVA

- median weight for cats in MVA cases: 4.3 kg

- median weight for cats in NAI cases: 3.6 kg

- cats involved in NAI weighed significantly less than cats involved in MVA

- NAI cases more likely to be intact (χ² = 58.0; p < 0.001) than MVA cases

- outcome

- 91.1% of MVA cases, survived

- 60% of NAI cases, survived (22% were dead on arrival)

“Multiple studies have demonstrated that cats are abused more often than dogs…”

Keywords

animal*; blunt force trauma*; dog*; forensic science*; injury*; motor vehicle accident*; non-accidental injury*; veterinary*;

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Comment In J Forensic Sci. 2017 May;62(3):829

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