Dog Attack ! Dog Bite Injuries

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Dog Attack ! Dog Bite Injuries

Jim Holliman, M.D., F.A.C.E.P.
Professor of Military and Emergency
Medicine Uniformed Services University of
the Health Sciences Clinical
Professor of Emergency Medicine
George Washington University

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Dog Bite Injuries Lecture Outline

• Epidemiology
• Clinical management
• Sample cases
• Advice on prevention
• Rabies
• Epidemiology
• Recognition
• Prophylaxis

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Relative Annual Human Death Rates (Worldwide)

• Suicides 400,000
• Murders 200,000
• Snakebites 60,000
• Crocodiles 1,000
• Farm animals 800 (mostly from kick injuries)
• Tigers 500 (?)
  
• 1 million people eaten over last 5 centuries
• Lions 400
• Leopards 300
• Hippos 300
• Elephants 200
• Dogs ? several hundred

So people are far more dangerous to people than
are animals !
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Human Injuries from Wild Wolves

• Asian Wolf is extremely dangerous
• Reports of packs attacking rural villages
• High incidence of rabies in Central Asia and Iran
• By contrast, for the two North American wolf
  species (Gray and Red) there are no reports of
  unprovoked human attacks in the last century
• Bites from North American coyotes also very rare
  unless directly provoked

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Mammal Bites By Species in the U.S.

• New York City
• Dogs 89
• Cats 4.6
• Rodents 2.2
• Humans 3.6 !
• Ohio
• Dogs 91.6
• Cats 4.5
• Rodents 3
• Humans 0.03

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Mammal Bites Epidemiology in U.S.

• gt 50 million pet cats dogs in U.S.
• gt 1,000,000 bites / year in U.S.
• 200 to 800 bites / 100,000 people per year
• 80 to 90 of bites due to dogs
• 1 to 2 of bites need admission
• 10 to 12 deaths from dog bites per year
• Tremendous economic cost

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More Dog Bite Epidemiology

• Overall 60 of cases in males
• Death rate 0.05 per 100,000 in U.S.
• 0.004 per 100,000 in Australia
• 70 to 80 of deaths in children less than 10
  years old
• Next most common age group for death is gt age 70
• Highest incidence in one year old children in
  some studies
• For each U.S. fatality, there are 670
  hospitalizations and 16,000 E.D. visits
• About 50 of injuries in children are to face
  scalp

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Risk Factors for Death from Dog Bites in U.S.
Studies

• More than one dog involved (64 )
• Owner's property (70 )
• History of prior aggression
• Sleeping infant
• Child's unauthorized access to fenced yard or
  leashed dog
• Dog escaping enclosure or restraint
• Certain breeds (next 2 slides)

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Incidence of Dog Bites (By Breed)
Decreasing
German Shepherd most common
Incidence
Mixed breeds
Doberman
St. Bernard
Great Dane
Rottweiler
Collie
Pekingese
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Incidence of Fatal Dog Bites (By Breed)
Decreasing
Pit bull most common
Incidence
Mixed pit bull breeds
Rottweiler
German Shepherd
Husky
Alaskan Malamute
Doberman
Great Dane
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Fatal Dog Bites

• Injuries concentrated about head and neck
  (injuries only on limbs in most non-fatal bites)
• Fatal attacks cannot be predicted from the dog's
  prior behavior
• Most offending dogs revert to normal friendly
  behavior after the attack
• Therefore infants and disabled should never be
  left alone with a large dog

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Different Bacteria Isolated from Dog Bite
Wounds (over 50 genuses have been reported)

• Most common
• Staph. aureus (30 )
• Staph. epidermidis (10 to 20)
• Strep. various species (50 )
• Corynebacterium (10 to 30 )
• Gram neg. such as E. coli
• Anerobes
• Bacteroides
• Fusobacterium
• Peptostreptococcus
• Actinomyces

• Less common
• Pasturella multocida (zero incidence in some
  reports but up to 40 in others)
• Pasturella canis
• Brucella canis
• Eikenella corrodens
• Moraxella sp.
• Neisseria sp.
• Capnocytophaga canimorsus (DF2)

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Capnocytophaga canimorsus Infections from Dog
Bites

• Older reports quoted 25 mortality rate
• Can cause septic arthritis, endocarditis, renal
  failure, D.I.C., sepsis, and / or meningitis
• Recent review of 19 meningitis cases noted only
  one death in this group
• Immunocompromised, post-splenectomy, and
  alcoholic patients at higher risk
• Usually sensitive to penicillin, rifampin,
  quinolones
• Usually resistant to aztreonam, aminoglycosides,
  and trimethoprim

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Considerations About Pasturella multocida
Infections from Dog Bites

• Can cause very rapid cellulitis (erythema within
  2 hours)
• Can cause complications in up to 40
• Local septic arthritis
• Osteomyelitis
• Tenosynovitis
• Bacteremia
• Rarely pneumonia or pulmonary abscess in
  immunocpmpromised patients
• Disseminated pasteurellosis in patients with
  liver disease

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Other Uncommon Dog Bite Infections

• Fungi
• Myocobacteria such as M. fortuitum
• Clostridium tetani (Tetanus)
• Rabies

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Average Infection Rates From Mammal
Bites
Dogs
2 to 5
Cats
30 to 50
Rats
2 to 10
Monkeys
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Humans
13 to 50
However up to 30 for hand bites Higher rates
reported mainly from delayed presentations
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Dog Bites Increased Infection Risk
Factors

• Age lt 2 or gt 50 years
• Diabetes
• Immunosuppressive illness
• Chronic alcoholism
• Puncture wounds
• Large wounds
• Extremities
• Delayed (gt 4 hours) presentation

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Dog Bites Use of Wound Cultures

• Initial (fresh) animal bite wound cultures
• Not recommended
• Initial culture results do not correlate with
  later proven infecting organisms
• However if the patient presents delayed, with
  signs of infection, then wound cultures are useful

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Summary of Emergency Department Management of Dog
Bite Injuries

• Usual assessment for blood loss or dangerous
  associated injuries, control any active bleeding.
• Consider need for radiographs (see next slide).
• Culture wound if already infected or delayed
  presentation.
• Copiously irrigate wound (/- debridement as
  needed).
• Primary suture repair for most wounds (may elect
  secondary delayed closure for large, delayed,
  already infected, hand, or foot wounds).
• Consider antibiotic prophylaxis.
• Consider need for rabies vaccination check
  tetanus status.
• Report to police or local animal authority.

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Considerations About Radiographs for Dog Bite
Cases

• Large dogs can generate forces gt 500 foot-pounds
  per square inch with their jaws
• Therefore can cause extremity long bone fractures
• Also can cause dural penetration from scalp bites
  in small children (this can lead to fatal
  meningitis if missed in the E.D.)
• So skull films may be needed to see if there is
  inner table penetration from teeth

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Dog Bites Rules for Prophylactic
Antibiotics

• 5 studies have found prophylaxis not indicated
• However several studies advise prophylaxis for
  hand, foot, and delayed presentation bites
• Also consider for very large bites requiring
  suture repair, and if any question of tooth
  penetration into periosteum
• Clearly not needed for simple shallow bites of
  the face or scalp

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Best Prophylactic Antibiotic Choices for Dog
Bites

• Need to cover for Staph. aureus
• Dicloxacillin or cephalexin 500 mg PO qid x 7
  days
• Erythromycin or azithromycin if patient PCN
  allergic
• Penicillin VK 500 mg PO qid x 7 days if
  Pasteurella multocida suspected (Pasteurella
  usually resistant to cephalosporins,
  tetracycline, erythromycin)
• Note Amoxicillin / clavulanate often touted as
  antibiotic of choice for bites but THERE IS ZERO
  LITERATURE EVIDENCE FOR THIS (is expensive has
  high side effects also in my study from 1994
  the only empiric failures were in those given
  amoxicillin / clavulanate)

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Dog Bites Criteria for Hospital
Admission

• Admit to hospital if
• Patient presents with deep established infection
• Possible penetration of joint capsule
• Surgical (Operating Room) repair required
• Such as for tooth penetration of dura
• Associated fracture present

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Dog bite lacerations of the face
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Same patient after primary suture repair
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Same patient after healing, with good cosmetic
outcome
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Left flexor tenosynovitis from dog bite requiring
surgical management
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Child bitten by a ferret
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Another child bitten by a ferret
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All these should have primary suture repair
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Facial lacerations from dog bite before and after
repair
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Cost Comparisons of Some Rx Items for Animal
Bites (Pennsylvania, 2006)

• Penicillin VK 500 mg PO qid for 7 days
  4.20
• Dicloxacillin 500 mg PO qid for 7 days
  11.76
• Cefalexin 500 mg PO qid for 7 days
  6.44
• Augmentin 500 mg PO tid for 7 days
  40.32
• Cefazolin 1 gram IV
  0.89
• Nafcillin 1 gram IV
  5.83
• Ceftriaxone 1 gram IV
  32.21
• 5 cc. Rabies Immune Globulin IM
  302.85
• 5 one cc. doses HDCV
  517.80
• Wound culture / sensitivity
  66.00

Note the IV costs listed do not include the
nursing administration fees
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Aspects of Dog Behavior Which Influence Dog Bite
Prevention Measures

• Dogs sniff as a means of communication
• Dogs like to chase moving objects
• Dogs run faster than humans
• Screaming may incite predatory behavior
• Direct eye contact may be interpreted as
  aggression
• Lying on the ground provokes attack
• Dogs tend to attack extemities, face, and neck
• Dogs which are fighting tend to bite at anything
  else that is near

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Standard Advice to Lessen Risk of Dog Bite Attacks

• Before petting a dog, let it sniff you
• Do not run past dogs
• Do not try to outrun a dog
• Remain calm if a dog approaches
• Do not hug or kiss a dog
• Avoid direct eye contact with dogs
• If attacked, hold feet together and protect neck
  and face
• Do not try to stop 2 fighting dogs
• Do not disturb a dog which is eating, sleeping,
  or caring for puppies
• Educate children to do all of the above

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Rabies

• Caused by an RNA rhabdovirus
• Transmitted by inoculation of infectious saliva
• Rarely can be transmitted by inhalation (from
  bats in caves)
• Causes a severe, uniformly fatal encephalitis
• Only 5 documented survivors worldwide so far

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Rabies Incidence in U.S.A.

• 4,000 proven domestic animals / year
• Predominately dogs, cats, cattle
• 15,000 proven wild animals / year
• Represents sampling by state labs so true
  incidence is much higher
• Average 1 human death / year (about 800 worldwide
  human deaths reported per year)

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Rabies Clinical Progression

• Bite
• Incubation period weeks to months (no symptoms)
  shorter for head or neck bites
• Prodromal phase 2 days to 2 weeks
• Neurologic symptoms one week or more
• Paralytic phase several weeks to months

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Rabies Symptom Progression

• Prodrome phase fever, malaise, headache, sore
  throat
• Neurologic phase paresthesias at bite site,
  anxiety, restlessness, insomnia, dysphagia,
  hydrophobia (from fear of painful esophageal
  spasms), spasms, seizures
• Flaccid paralysis leads to coma
• Cardiovascular collapse
• Supportive treatment generally ineffective to
  date

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Risk of Rabies Transmission from
Animal Bite
High Risk Bats Raccoons Foxes Coyotes /
bobcats Other carnivores
Intermediate Risk "Outdoor" cats and
dogs Cattle in Midwest USA
Low Risk Rodents Lagomorphs (hares
rabbits) Farm animals Indoor cats and dogs
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Rabies Prophylaxis for Mammal Bite
Wounds

• Pennsylvania currently has second highest state
  rate in U.S. of wild animal rabies
• Raccoon - based epidemic in eastern U.S. since
  late 1970's
• State Public Health Laboratories will do exams of
  sacrificed animals for rabies
• Human Diploid Cell Vaccine (HDCV) is current
  agent of choice (replaces Duck Embryo Vaccine)
• Followup antibody titer after completion of
  series no longer recommended

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Protocol for Starting Rabies
Prophylaxis

• High risk bite animal escapes give
  prophylaxis
• High risk bite animal captured send animal's
  head to State Health Lab for path exam treat
  only if lab confirms rabid animal (brain sections
  show Negri bodies)
• Low risk animal animal escapes consider
  prophylaxis only if bite clearly unprovoked
• Low risk animal animal captured keep animal
  under reliable observation one week if animal
  gets sick immediate check by veterinarian or
  State Health Lab if animal remains well 7 days
  no Rx needed

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Rabies Prophylaxis

• Post-exposure
• HDCV 1.0 ml IM on days 0, 3, 7, 14, 28
• Plus Rabies Immune Globulin (RIG) 20 IU / kg IM
  on day 0
• Pre-exposure
• HDCV 1.0 ml IM on days 0, 7, 21
• This is utilized for forest rangers,
  veterinarians, others who have higher risk of
  encountering rabies
• Still requires booster dose after each exposure

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Countries Without Animal Rabies

• Pacific Islands
• Caribbean Islands
• United Kingdom
• Iceland
• Singapore
• Australia

• Portugal
• Spain
• Sweden
• Japan
• Taiwan

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Dog Bites Lecture Summary

• Consider need for radiographs
• Always perform careful wound cleansing
  irrigation
• Decide if antibiotics suture closure are
  indicated
• Assess for risk of rabies tetanus
• Assure close followup