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 InjuriesLecture Outlineƒ Epidemiologyƒ Clinical managementƒ Sample casesƒ Advice on preventionƒ Rabies

–Epidemiology–Recognition–Prophylaxis

Relative Annual Human Death Rates (Worldwide)

ƒ Suicides : 400,000ƒ Murders : 200,000ƒ Snakebites : 60,000ƒ Crocodiles : 1,000ƒ Farm animals : 800 (mostly from kick injuries)ƒ Tigers : 500 (?)

–1 million people eaten over last 5 centuriesƒ Lions : 400ƒ Leopards : 300ƒ Hippos : 300ƒ Elephants : 200ƒ Dogs : ? several hundred

So people are far more dangerous to people than are animals !

Human Injuries from Wild Wolvesƒ 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 yearƒ 80 to 90 % of bites due to dogsƒ 1 to 2 % of bites need admissionƒ 10 to 12 deaths from dog bites per yearƒ Tremendous economic cost

More Dog Bite Epidemiology

ƒ Overall 60 % of cases in malesƒ Death rate 0.05 per 100,000 in U.S.

–0.004 per 100,000 in Australiaƒ 70 to 80 % of deaths in children less than 10 years old

–Next most common age group for death is > age 70ƒ Highest incidence in one year old children in some

studiesƒ For each U.S. fatality, there are 670 hospitalizations

and 16,000 E.D. visitsƒ 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 aggressionƒ Sleeping infantƒ Child's unauthorized access to fenced

yard or leashed dogƒ Dog escaping enclosure or restraintƒ 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 Bitesƒ Injuries concentrated about head and

neck (injuries only on limbs in most non-fatal 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 Bitesƒ Older reports quoted 25 % mortality rateƒ Can cause septic arthritis, endocarditis, renal

failure, D.I.C., sepsis, and / or meningitisƒ Recent review of 19 meningitis cases noted only

one death in this groupƒ Immunocompromised, post-splenectomy, and

alcoholic patients at higher riskƒ Usually sensitive to penicillin, rifampin, &

quinolonesƒ Usually resistant to aztreonam, aminoglycosides,

and trimethoprim

Considerations About Pasturella multocida Infections from Dog Bitesƒ 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 Fungiƒ Myocobacteria such as M. fortuitumƒ Clostridium tetani (Tetanus)ƒ Rabies

Average Infection Rates From Mammal Bites

Dogs :

2 to 5 %*

Cats :

30 to 50 %

Rats :

2 to 10 %

Monkeys :

25 %

Humans :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 yearsƒ Diabetesƒ Immunosuppressive illnessƒ Chronic alcoholismƒ Puncture woundsƒ Large woundsƒ Extremitiesƒ 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 foot-pounds 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 BitesCriteria 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 : $ 4.20ƒ Dicloxacillin 500 mg PO qid for 7 days : $ 11.76ƒ Cefalexin 500 mg PO qid for 7 days : $ 6.44ƒ Augmentin 500 mg PO tid for 7 days : $ 40.32ƒ Cefazolin 1 gram IV : $ 0.89ƒ Nafcillin 1 gram IV : $ 5.83ƒ Ceftriaxone 1 gram IV : $ 32.21ƒ 5 cc. Rabies Immune Globulin IM : $ 302.85ƒ 5 one cc. doses HDCV : $ 517.80ƒ 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

ƒ Dogs sniff as a means of communicationƒ Dogs like to chase moving objectsƒ Dogs run faster than humansƒ Screaming may incite predatory behaviorƒ Direct eye contact may be interpreted as aggressionƒ Lying on the ground provokes attackƒ Dogs tend to attack extemities, face, and neckƒ 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 youƒ Do not run past dogsƒ Do not try to outrun a dogƒ Remain calm if a dog approachesƒ Do not hug or kiss a dogƒ Avoid direct eye contact with dogsƒ If attacked, hold feet together and protect neck and

faceƒ Do not try to stop 2 fighting dogsƒ Do not disturb a dog which is eating, sleeping, or

caring for puppiesƒ Educate children to do all of the above

Rabiesƒ Caused by an RNA rhabdovirusƒ Transmitted by inoculation of infectious salivaƒ 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, cattleƒ 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 Biteƒ Incubation period : weeks to months (no

symptoms) ; shorter for head or neck bitesƒ Prodromal phase : 2 days to 2 weeksƒ Neurologic symptoms : one week or moreƒ Paralytic phase : several weeks to months

Rabies : Symptom Progressionƒ Prodrome phase : fever, malaise,

headache, sore throatƒ Neurologic phase : paresthesias at bite

site, anxiety, restlessness, insomnia, dysphagia, hydrophobia (from fear of painful esophageal spasms), spasms, seizures

ƒ Flaccid paralysis : leads to comaƒ Cardiovascular collapseƒ Supportive treatment generally ineffective

to date

Risk of Rabies Transmission from Animal Bite

High RiskBatsRaccoonsFoxesCoyotes / bobcatsOther carnivores

Intermediate Risk"Outdoor" cats and dogsCattle in Midwest USA

Low RiskRodentsLagomorphs (hares & rabbits)Farm animalsIndoor 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 prophylaxisƒ 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 Islandsƒ Caribbean

Islandsƒ United

Kingdomƒ Icelandƒ Singaporeƒ Australia

ƒ Portugalƒ Spain ƒ Swedenƒ Japanƒ Taiwan

Dog BitesLecture Summary

ƒ Consider need for radiographsƒ Always perform careful wound cleansing

& irrigationƒ Decide if antibiotics & suture closure are

indicatedƒ Assess for risk of rabies & tetanusƒ Assure close followup