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
Dog Bite Injuries
Lecture Outline
ƒ Epidemiology
ƒ Clinical management
ƒ Sample cases
ƒ Advice on prevention
ƒ Rabies
–Epidemiology
–Recognition
–Prophylaxis
Relative Annual Human
Death Rates (Worldwide)
ƒ Suicides : 400,000
ƒ Murders : 200,000
ƒ Snakebites : 60,000
ƒ Crocodiles : 1,000
ƒ Farm animals : 800 (mostly from kick injuries)
ƒ Tigers : 500 (?)
–1 million people eaten over last 5 centuries
ƒ Lions : 400
ƒ Leopards : 300
So people are far
ƒ Hippos : 300
more dangerous to
people than are
ƒ Elephants : 200
animals !
ƒ Dogs : ? several hundred
Human Injuries from Wild Wolves
ƒ Asian Wolf is extremely dangerous
–Reports of packs attacking rural villages
–High incidence of rabies in Central Asia and
Iran
ƒ By contrast, for the two North American wolf
species (Gray and Red) there are no reports of
unprovoked human attacks in the last century
ƒ Bites from North American coyotes also very rare
unless directly provoked
Mammal Bites By Species in the
U.S.
ƒ New York City
–Dogs
: 89 %
–Cats
: 4.6 %
–Rodents : 2.2 %
–Humans : 3.6 % !
ƒ Ohio
–Dogs
: 91.6 %
–Cats
: 4.5 %
–Rodents : 3 %
–Humans : 0.03 %
Mammal Bites : Epidemiology
in U.S.
ƒ > 50 million pet cats & dogs in U.S.
ƒ > 1,000,000 bites / year in U.S.
ƒ 200 to 800 bites / 100,000 people per year
ƒ 80 to 90 % of bites due to dogs
ƒ 1 to 2 % of bites need admission
ƒ 10 to 12 deaths from dog bites per year
ƒ Tremendous economic cost
More Dog Bite Epidemiology
ƒ Overall 60 % of cases in males
ƒ Death rate 0.05 per 100,000 in U.S.
–0.004 per 100,000 in Australia
ƒ 70 to 80 % of deaths in children less than 10 years old
–Next most common age group for death is > age 70
ƒ Highest incidence in one year old children in some
studies
ƒ For each U.S. fatality, there are 670 hospitalizations
and 16,000 E.D. visits
ƒ About 50 % of injuries in children are to face & scalp
Risk Factors for Death from
Dog Bites in U.S. Studies
ƒ More than one dog involved (64 %)
ƒ Owner's property (70 %)
ƒ History of prior aggression
ƒ Sleeping infant
ƒ Child's unauthorized access to fenced
yard or leashed dog
ƒ Dog escaping enclosure or restraint
ƒ Certain breeds (next 2 slides)
Incidence of Dog Bites (By Breed)
Decreasing
German Shepherd : most common
Incidence
Mixed breeds
Doberman
St. Bernard
Great Dane
Rottweiler
Collie
Pekingese
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
Fatal Dog Bites
ƒ Injuries concentrated about head and
neck (injuries only on limbs in most nonfatal bites)
ƒ Fatal attacks cannot be predicted from
the dog's prior behavior
ƒ Most offending dogs revert to normal
friendly behavior after the attack
ƒ Therefore infants and disabled should
never be left alone with a large dog
Different Bacteria Isolated from Dog
Bite Wounds
(over 50 genuses have been reported)
ƒ Most common :
–Staph. aureus (30 %)
–Staph. epidermidis (10 to 20%)
–Strep. various species (50 %)
–Corynebacterium (10 to 30 %)
–Gram neg. such as E. coli
ƒ Anerobes :
–Bacteroides
–Fusobacterium
–Peptostreptococcus
–Actinomyces
ƒ 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)
Capnocytophaga canimorsus
Infections from Dog Bites
ƒ Older reports quoted 25 % mortality rate
ƒ Can cause septic arthritis, endocarditis, renal
failure, D.I.C., sepsis, and / or meningitis
ƒ Recent review of 19 meningitis cases noted only
one death in this group
ƒ Immunocompromised, post-splenectomy, and
alcoholic patients at higher risk
ƒ Usually sensitive to penicillin, rifampin, &
quinolones
ƒ Usually resistant to aztreonam, aminoglycosides,
and trimethoprim
Considerations About Pasturella
multocida Infections from Dog
Bites
ƒ Can cause very rapid cellulitis (erythema within 2
hours)
ƒ 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
Other Uncommon Dog Bite
Infections
ƒ Fungi
ƒ Myocobacteria such as M. fortuitum
ƒ Clostridium tetani (Tetanus)
ƒ Rabies
Average Infection Rates From
Mammal Bites
Dogs :
2 to 5 %*
Cats :
30 to 50 %
Rats :
2 to 10 %
Monkeys :
Humans :
25 %
13 to 50 %**
*However up to 30 % for hand bites
**Higher rates reported mainly from delayed
presentations
Dog Bites :
Increased Infection Risk Factors
ƒ Age < 2 or > 50 years
ƒ Diabetes
ƒ Immunosuppressive illness
ƒ Chronic alcoholism
ƒ Puncture wounds
ƒ Large wounds
ƒ Extremities
ƒ Delayed (> 4 hours) presentation
Dog Bites :
Use of Wound Cultures
ƒ 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
Summary of Emergency
Department Management of
Dog Bite Injuries
ƒ Usual assessment for blood loss or dangerous associated
injuries, control any active bleeding.
ƒ Consider need for radiographs (see next slide).
ƒ Culture wound if already infected or delayed presentation.
ƒ Copiously irrigate wound (+/- debridement as needed).
ƒ Primary suture repair for most wounds (may elect secondary
delayed closure for large, delayed, already infected, hand, or
foot wounds).
ƒ Consider antibiotic prophylaxis.
ƒ Consider need for rabies vaccination ; check tetanus status.
ƒ Report to police or local animal authority.
Considerations About Radiographs
for Dog Bite Cases
ƒ Large dogs can generate forces > 500 footpounds per square inch with their jaws
–Therefore can cause extremity long bone
fractures
ƒ 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
Dog Bites :
Rules for Prophylactic Antibiotics
ƒ 5 studies have found prophylaxis not
indicated
ƒ However several studies advise prophylaxis
for hand, foot, and delayed presentation bites
ƒ Also consider for very large bites requiring
suture repair, and if any question of tooth
penetration into periosteum
ƒ Clearly not needed for simple shallow bites of
the face or scalp
Best Prophylactic Antibiotic
Choices for Dog Bites
ƒ 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)
ƒ 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)
Dog Bites
Criteria for Hospital Admission
ƒ Admit to hospital if :
–Patient presents with deep established
infection
–Possible penetration of joint capsule
–Surgical (Operating Room) repair required
ƒ Such as for tooth penetration of dura
–Associated fracture present
Dog bite lacerations of the face
Same patient after primary suture repair
Same patient after healing, with good cosmetic outcome
Left flexor tenosynovitis from dog bite requiring surgical
management
Child bitten by a ferret
Another child bitten by a ferret
All these should have primary suture repair
Facial
lacerations from
dog bite before
and after repair
Cost Comparisons of Some
Rx Items for Animal Bites
(Pennsylvania, 2006)
ƒ Penicillin VK 500 mg PO qid for 7 days :
ƒ Dicloxacillin 500 mg PO qid for 7 days :
ƒ Cefalexin 500 mg PO qid for 7 days :
ƒ Augmentin 500 mg PO tid for 7 days :
ƒ Cefazolin 1 gram IV :
ƒ Nafcillin 1 gram IV :
ƒ Ceftriaxone 1 gram IV :
ƒ 5 cc. Rabies Immune Globulin IM :
ƒ 5 one cc. doses HDCV :
ƒ Wound culture / sensitivity :
$ 4.20
$ 11.76
$ 6.44
$ 40.32
$ 0.89
$ 5.83
$ 32.21
$ 302.85
$ 517.80
$ 66.00
Note : the IV costs listed do not include the nursing
administration fees
Aspects of Dog Behavior Which
Influence Dog Bite Prevention
Measures
ƒ Dogs sniff as a means of communication
ƒ Dogs like to chase moving objects
ƒ Dogs run faster than humans
ƒ Screaming may incite predatory behavior
ƒ Direct eye contact may be interpreted as
aggression
ƒ Lying on the ground provokes attack
ƒ Dogs tend to attack extemities, face, and neck
ƒ Dogs which are fighting tend to bite at anything else
that is near
Standard Advice to Lessen
Risk of Dog Bite Attacks
ƒ Before petting a dog, let it sniff you
ƒ Do not run past dogs
ƒ Do not try to outrun a dog
ƒ Remain calm if a dog approaches
ƒ Do not hug or kiss a dog
ƒ Avoid direct eye contact with dogs
ƒ If attacked, hold feet together and protect neck and
face
ƒ Do not try to stop 2 fighting dogs
ƒ Do not disturb a dog which is eating, sleeping, or
caring for puppies
ƒ Educate children to do all of the above
Rabies
ƒ Caused by an RNA rhabdovirus
ƒ Transmitted by inoculation of infectious saliva
ƒ Rarely can be transmitted by inhalation (from
bats in caves)
ƒ Causes a severe, uniformly fatal encephalitis
–Only 5 documented survivors worldwide so
far
Rabies Incidence in U.S.A.
ƒ 4,000 proven domestic animals / year
–Predominately dogs, cats, cattle
ƒ 15,000 proven wild animals / year
–Represents sampling by state labs so true
incidence is much higher
ƒ Average 1 human death / year (about 800
worldwide human deaths reported per year)
Rabies : Clinical Progression
ƒ Bite
ƒ Incubation period : weeks to months (no
symptoms) ; shorter for head or neck bites
ƒ Prodromal phase : 2 days to 2 weeks
ƒ Neurologic symptoms : one week or more
ƒ Paralytic phase : several weeks to months
Rabies : Symptom Progression
ƒ Prodrome phase : fever, malaise,
headache, sore throat
ƒ Neurologic phase : paresthesias at bite
site, anxiety, restlessness, insomnia,
dysphagia, hydrophobia (from fear of
painful esophageal spasms), spasms,
seizures
ƒ Flaccid paralysis : leads to coma
ƒ Cardiovascular collapse
ƒ Supportive treatment generally ineffective
to date
Risk of Rabies Transmission
from Animal Bite
High Risk
Intermediate Risk
Bats
"Outdoor" cats
Raccoons
and dogs
Foxes
Cattle in Midwest
Coyotes /
USA
bobcats
Other carnivores
Low Risk
Rodents
Lagomorphs
(hares &
rabbits)
Farm animals
Indoor cats and
dogs
Rabies Prophylaxis for
Mammal Bite Wounds
ƒ Pennsylvania currently has second highest state
rate in U.S. of wild animal rabies
ƒ Raccoon - based epidemic in eastern U.S. since
late 1970's
ƒ State Public Health Laboratories will do exams of
sacrificed animals for rabies
ƒ Human Diploid Cell Vaccine (HDCV) is current
agent of choice (replaces Duck Embryo Vaccine)
ƒ Followup antibody titer after completion of series
no longer recommended
Protocol for Starting Rabies
Prophylaxis
ƒ High risk bite & animal escapes : give prophylaxis
ƒ 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)
ƒ Low risk animal & animal escapes : consider
prophylaxis only if bite clearly unprovoked
ƒ 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
Rabies Prophylaxis
ƒ 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
ƒ 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
Countries Without
Animal Rabies
ƒ Pacific Islands
ƒ Caribbean
Islands
ƒ United
Kingdom
ƒ Iceland
ƒ Singapore
ƒ Australia
ƒ Portugal
ƒ Spain
ƒ Sweden
ƒ Japan
ƒ Taiwan
Dog Bites
Lecture Summary
ƒ Consider need for radiographs
ƒ Always perform careful wound cleansing
& irrigation
ƒ Decide if antibiotics & suture closure are
indicated
ƒ Assess for risk of rabies & tetanus
ƒ Assure close followup