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

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Epidemiology

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Clinical management

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Sample cases

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Advice on prevention

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Rabies

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Epidemiology

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Recognition

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Prophylaxis

Relative Annual Human Death Rates (Worldwide)

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Suicides : 400,000

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Murders : 200,000

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Snakebites : 60,000

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Crocodiles : 1,000

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Farm animals : 800 (mostly from kick injuries)

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Tigers : 500 (?)

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1 million people eaten over last 5 centuries

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Lions : 400

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Leopards : 300 So people are far

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Hippos : 300

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Elephants : 200

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Dogs : ? several hundred more dangerous to people than are animals !

Human Injuries from Wild Wolves

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Asian Wolf is extremely dangerous

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Reports of packs attacking rural villages

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High incidence of rabies in Central Asia and Iran

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By contrast, for the two North American wolf species (Gray and Red) there are no reports of unprovoked human attacks in the last century

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Bites from North American coyotes also very rare unless directly provoked

Mammal Bites By Species in the U.S.

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New York City

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Dogs : 89 %

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Cats : 4.6 %

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Rodents : 2.2 %

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Humans : 3.6 % !

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Ohio

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Dogs : 91.6 %

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Cats : 4.5 %

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Rodents : 3 %

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Humans : 0.03 %

Mammal Bites : Epidemiology in U.S.

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> 50 million pet cats & dogs in U.S.

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> 1,000,000 bites / year in U.S.

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200 to 800 bites / 100,000 people per year

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80 to 90 % of bites due to dogs

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1 to 2 % of bites need admission

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10 to 12 deaths from dog bites per year

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Tremendous economic cost

More Dog Bite Epidemiology

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Overall 60 % of cases in males

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Death rate 0.05 per 100,000 in U.S.

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0.004 per 100,000 in Australia

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70 to 80 % of deaths in children less than 10 years old

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Next most common age group for death is > age 70

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Highest incidence in one year old children in some studies

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For each U.S. fatality, there are 670 hospitalizations and 16,000 E.D. visits

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About 50 % of injuries in children are to face & scalp

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

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More than one dog involved (64 %)

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Owner's property (70 %)

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History of prior aggression

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Sleeping infant

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Child's unauthorized access to fenced yard or leashed dog

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Dog escaping enclosure or restraint

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Certain breeds (next 2 slides)

Incidence of Dog Bites (By Breed) 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

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Injuries concentrated about head and neck (injuries only on limbs in most non fatal bites)

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Fatal attacks cannot be predicted from the dog's prior behavior

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Most offending dogs revert to normal friendly behavior after the attack

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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)

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Most common :

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Staph. aureus (30 %)

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Staph. epidermidis (10 to 20%)

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Strep. various species (50 %)

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Corynebacterium (10 to 30 %)

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Gram neg. such as E. coli

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Anerobes :

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Bacteroides

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Fusobacterium

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Peptostreptococcus

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Actinomyces

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Less common :

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Pasturella multocida (zero incidence in some reports but up to 40 % in others)

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Pasturella canis

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Brucella canis

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Eikenella corrodens

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Moraxella sp.

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Neisseria sp.

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Capnocytophaga canimorsus (DF2)

Capnocytophaga canimorsus Infections from Dog Bites

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Older reports quoted 25 % mortality rate

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Can cause septic arthritis, endocarditis, renal failure, D.I.C., sepsis, and / or meningitis

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Recent review of 19 meningitis cases noted only one death in this group

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Immunocompromised, post-splenectomy, and alcoholic patients at higher risk

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Usually sensitive to penicillin, rifampin, & quinolones

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Usually resistant to aztreonam, aminoglycosides, and trimethoprim

Considerations About Pasturella multocida Infections from Dog Bites

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Can cause very rapid cellulitis (erythema within 2 hours)

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Can cause complications in up to 40 % :

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Local septic arthritis

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Osteomyelitis

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Tenosynovitis

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Bacteremia

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Rarely pneumonia or pulmonary abscess in immunocpmpromised patients

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Disseminated pasteurellosis in patients with liver disease

Other Uncommon Dog Bite Infections

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Fungi

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Myocobacteria such as M. fortuitum

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Clostridium tetani (Tetanus)

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Rabies

Average Infection Rates From Mammal Bites Dogs : Cats : Rats : Monkeys : Humans : 2 to 5 %* 30 to 50 % 2 to 10 % 25 % 13 to 50 %** *However up to 30 % for hand bites **Higher rates reported mainly from delayed presentations

Dog Bites : Increased Infection Risk Factors

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Age < 2 or > 50 years

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Diabetes

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Immunosuppressive illness

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Chronic alcoholism

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Puncture wounds

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Large wounds

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Extremities

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Delayed (> 4 hours) presentation

Dog Bites : Use of Wound Cultures

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Initial (fresh) animal bite wound cultures :

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Not recommended

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Initial culture results do not correlate with later proven infecting organisms

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However if the patient presents delayed, with signs of infection, then wound cultures are useful

Summary of Emergency Department Management of Dog Bite Injuries

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Usual assessment for blood loss or dangerous associated injuries, control any active bleeding.

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Consider need for radiographs (see next slide).

Culture wound if already infected or delayed presentation.

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Copiously irrigate wound (+/- debridement as needed).

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Primary suture repair for most wounds (may elect secondary delayed closure for large, delayed, already infected, hand, or foot wounds).

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Consider antibiotic prophylaxis.

Consider need for rabies vaccination ; check tetanus status.

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Report to police or local animal authority.

Considerations About Radiographs for Dog Bite Cases

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Large dogs can generate forces > 500 foot pounds per square inch with their jaws

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Therefore can cause extremity long bone fractures

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Also can cause dural penetration from scalp bites in small children (this can lead to fatal meningitis if missed in the E.D.)

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So skull films may be needed to see if there is inner table penetration from teeth

Dog Bites : Rules for Prophylactic Antibiotics

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5 studies have found prophylaxis not indicated

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However several studies advise prophylaxis for hand, foot, and delayed presentation bites

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Also consider for very large bites requiring suture repair, and if any question of tooth penetration into periosteum

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Clearly not needed for simple shallow bites of the face or scalp

Best Prophylactic Antibiotic Choices for Dog Bites

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Need to cover for Staph. aureus :

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Dicloxacillin or cephalexin 500 mg PO qid x 7 days

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Erythromycin or azithromycin if patient PCN allergic

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Penicillin VK 500 mg PO qid x 7 days if Pasteurella multocida suspected (Pasteurella usually resistant to cephalosporins, tetracycline, erythromycin)

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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

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Admit to hospital if :

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Patient presents with deep established infection

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Possible penetration of joint capsule

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Surgical (Operating Room) repair required

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Such as for tooth penetration of dura

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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)

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Penicillin VK 500 mg PO qid for 7 days : $ 4.20

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Dicloxacillin 500 mg PO qid for 7 days : $ 11.76

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Cefalexin 500 mg PO qid for 7 days : $ 6.44

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Augmentin 500 mg PO tid for 7 days : $ 40.32

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Cefazolin 1 gram IV : $ 0.89

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Nafcillin 1 gram IV : $ 5.83

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Ceftriaxone 1 gram IV : $ 32.21

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5 cc. Rabies Immune Globulin IM : $ 302.85

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5 one cc. doses HDCV : $ 517.80

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Wound culture / sensitivity : $ 66.00

Note : the IV costs listed do not include the nursing administration fees

Aspects of Dog Behavior Which Influence Dog Bite Prevention Measures

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Dogs sniff as a means of communication

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Dogs like to chase moving objects

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Dogs run faster than humans

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Screaming may incite predatory behavior

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Direct eye contact may be interpreted as aggression

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Lying on the ground provokes attack

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Dogs tend to attack extemities, face, and neck

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Dogs which are fighting tend to bite at anything else that is near

Standard Advice to Lessen Risk of Dog Bite Attacks

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Before petting a dog, let it sniff you

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Do not run past dogs

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Do not try to outrun a dog

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Remain calm if a dog approaches

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Do not hug or kiss a dog

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Avoid direct eye contact with dogs

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If attacked, hold feet together and protect neck and face

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Do not try to stop 2 fighting dogs

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Do not disturb a dog which is eating, sleeping, or caring for puppies

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Educate children to do all of the above

Rabies

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Caused by an RNA rhabdovirus

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Transmitted by inoculation of infectious saliva

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Rarely can be transmitted by inhalation (from bats in caves)

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Causes a severe, uniformly fatal encephalitis

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Only 5 documented survivors worldwide so far

Rabies Incidence in U.S.A.

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4,000 proven domestic animals / year

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Predominately dogs, cats, cattle

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15,000 proven wild animals / year

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Represents sampling by state labs so true incidence is much higher

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Average 1 human death / year (about 800 worldwide human deaths reported per year)

Rabies : Clinical Progression

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Bite

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Incubation period : weeks to months (no symptoms) ; shorter for head or neck bites

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Prodromal phase : 2 days to 2 weeks

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Neurologic symptoms : one week or more

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Paralytic phase : several weeks to months

Rabies : Symptom Progression

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Prodrome phase : fever, malaise, headache, sore throat

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Neurologic phase : paresthesias at bite site, anxiety, restlessness, insomnia, dysphagia, hydrophobia (from fear of painful esophageal spasms), spasms, seizures

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Flaccid paralysis : leads to coma

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Cardiovascular collapse

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Supportive treatment generally ineffective to date

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

Rabies Prophylaxis for Mammal Bite Wounds

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Pennsylvania currently has second highest state rate in U.S. of wild animal rabies

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Raccoon - based epidemic in eastern U.S. since late 1970's

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State Public Health Laboratories will do exams of sacrificed animals for rabies

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Human Diploid Cell Vaccine (HDCV) is current agent of choice (replaces Duck Embryo Vaccine)

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Followup antibody titer after completion of series no longer recommended

Protocol for Starting Rabies Prophylaxis

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High risk bite & animal escapes : give prophylaxis

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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)

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Low risk animal & animal escapes : consider prophylaxis only if bite clearly unprovoked

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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

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Post-exposure :

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HDCV 1.0 ml IM on days 0, 3, 7, 14, 28

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Plus Rabies Immune Globulin (RIG) 20 IU / kg IM on day 0

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Pre-exposure :

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HDCV 1.0 ml IM on days 0, 7, 21

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This is utilized for forest rangers, veterinarians, & others who have higher risk of encountering rabies

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Still requires booster dose after each exposure

Countries Without Animal Rabies

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Pacific Islands

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Caribbean Islands

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United Kingdom

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Iceland

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Singapore

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Australia

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Portugal

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Spain

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Sweden

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Japan

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Taiwan

Dog Bites Lecture Summary

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Consider need for radiographs

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Always perform careful wound cleansing & irrigation

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Decide if antibiotics & suture closure are indicated

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Assess for risk of rabies & tetanus

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Assure close followup