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

Abstract

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*;