Bites, Animal


Article Author:
Kenneth Maniscalco


Article Editor:
Mary Ann Edens


Editors In Chief:
David Wood
Andrew Wilt
Hajira Basit


Managing Editors:
Avais Raja
Orawan Chaigasame
Khalid Alsayouri
Kyle Blair
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Abbey Smiley
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beenish Sohail
Hajira Basit
Phillip Hynes
Sandeep Sekhon


Updated:
11/15/2018 3:58:02 PM

Introduction

Animal bites account for approximately one percent of all ED visits in the U.S. yearly and range from superficial injuries to disfiguring and even fatal wounds.  Even relatively minor wounds have the capacity to become infected, and therefore all bites should be evaluated carefully and thoroughly with a mind to potential complications.  This chapter will focus on dog and cat bites and the common sequelae as they are the most prevalent, and when considered with human bites (which will be discussed in another chapter) account for over 95% of the total bite wounds seen in the ED. [1][2][3]

Etiology

Domesticated cats and dogs inflict practically all of the bites encountered in the ED in the United States.  The most common complication is local wound infection. Infections resulting from bites of all animal species are poly-microbial with aerobic and anaerobic bacteria; dogs and cats have an oral flora of Pasteurella, Staph, and Strep most commonly.  In cat bites and scratches, Bartonella infections are an additional concern.  Dog bites in immunocompromised individuals, especially asplenic patients, raise concern for a Capnocytophaga sepsis. [4]      

Epidemiology

Dog bites predominate (60-90%) followed by cat bites (5-20%).  Children are more commonly bitten on the head, face, and neck due to their proportionately larger heads and shorter stature while adults are more commonly bitten on the hands and arms.  Dog bites happen more in men and children.  The patient usually knows the dogs and the bites are less commonly provoked.  Cat bites are more common in women and adults, and the bites are more often provoked.  In less traumatic bites, especially cat bites due to the puncturing nature of cat teeth, the patient will commonly only present after the infection has become apparent and management has become more complicated.[5][1]

Pathophysiology

The initial injury is the result of the physical trauma of teeth puncturing and/or tearing soft tissue, and in the case of some dog bites, blunt force breaking bones. Dog bites are more commonly macerated due to the ripping and tearing forces involved.  Cat bites are narrow and deep as the animal rarely pulls or shakes its head, simply biting and holding.  Because the cat bite wound is deep and narrow, it is much more likely to seal itself relatively quickly, providing an anaerobic environment for the inoculated bacteria as well as initially appearing less consequential and prolonging time to seeking medical care.  

History and Physical

Focused H&P should determine the circumstances surrounding the bite, location of the bite, type of animal, time of occurrence, whether the patient has been febrile, local erythema, swelling, warmth, or purulent drainage.  If the patient is stable, the wound should be thoroughly explored after local or regional anesthesia to determine the potential for damage to underlying structures and foreign body inoculation. Local and distal neurovascular status should be assessed after anesthesia as well as pain and apprehension may affect patient compliance with the exam.  Pertinent history includes any immunosuppression, be it iatrogenic (transplant, rheumatic disease treatment) or from a disease process (diabetes, HIV/AIDS, sickle cell disease.).     

Evaluation

As with all traumas, the initial evaluation is to ensure airway, breathing, and circulation is intact.  Active venous bleeding should be controlled with direct pressure while arterial bleeding will typically necessitate consult services.  The wound should be explored for foreign bodies such as broken teeth, claws, dirt, and plant material.  When exploring the wound underlying structures should be examined for potential damage as well.  During exploration, the patient should range the underlying structures through a full range of motion to ensure that injuries to those underlying structures are not missed.  [2]

Treatment / Management

All wounds should be extensively irrigated and the patient’s tetanus status updated if necessary.  Provide appropriate pain management before exploration, irrigation, or debridement of the wounds.  The patient’s TDaP status should be updated if necessary.  For uncomplicated dog bites, the patient should be educated on the risk/benefit of closure versus healing by secondary intention and the decision made with the provider.  If the patient presents delayed from the initial bite the risks of closing the wound almost certainly outweigh the cosmetic benefits of closure.  If the wound is closed, the patient should be discharged with a week’s course of amoxicillin-clavulanate.  Complicated dog bites should be stabilized and referred to the appropriate consult service.  Cat bites deeper than superficial should be irrigated thoroughly under local anesthesia and the wound left open.  The patient should be discharged with a week’s course of amoxicillin-clavulanate and given strict wound care precautions.  All bites to the hands or feet, bites in immunocompromised individuals, bites which already show signs of infection, and bites which have a puncture characteristic should be treated with amoxicillin-clavulanate.  For patients with penicillin allergies, second-line therapy is doxycycline or TMP-SMX plus metronidazole or clindamycin.  Patients with extensive local infection should be seen by the appropriate consult service, patients with evidence of disseminated infection should be treated with broad-spectrum IV antibiotics and admitted for further care.[6][7][8]

Prognosis

The prognosis for most animal bites is excellent. However, it is important to know that on average about 30-50 people die from dog bites each year.

Complications

  • Cellulitis
  • Tenosynovitis
  • Endocarditis
  • Osteomyelitis
  • Abscess
  • Meningitis
  • Tendon rupture
  • Nerve injury
  • PTSD
  • Rabies

Postoperative and Rehabilitation Care

Patients with animal bites need to be seen within 48-72 hours after initial treatment to ensure that they are not developing an infection. The animal should be removed from the home and placed in a different location.

Deterrence and Patient Education

Patients should be encouraged to be updated with tetanus vaccination.

Pearls and Other Issues

  1. Rabies is rarely a concern due to the broad vaccination program in domesticated animals and the fact that the patient usually knows the animal. Depending on the local prevalence of the disease you may be able to defer rabies prophylaxis for dog and cat bites. 
  2. If the status of the animal is unknown rabies prophylaxis may be deferred if the animal is in custody and may be observed or has been dissected for evaluation of rabies.  Most commonly rabies is found in bat and skunk populations. 
  3. Any bite or suspected bite from a bat should be treated with rabies prophylaxis.  Rabies prophylaxis initiation in the ED requires the rabies vaccine provided in a distant site from the injury with as much of the required rabies immune globulin being given local to the wound. 
  4. Further rabies vaccine doses should be given on days three, seven, and fourteen. 
  5. Immunocompromised individuals with cat bites or scratches should be covered with TMP-SMX, ciprofloxacin, or rifampin as prophylaxis against cat-scratch disease.
  6. Sepsis from Capnocytophaga is covered by standard prophylaxis in dog bites in immunocompromised individuals. 
  7. Bites from K-9 officers should be treated similarly as the above with the additional documentation that the officers will require. 

Enhancing Healthcare Team Outcomes

About 300,000 people with dog bites visit the emergency room or the primary care provider each year. The earlier the treatment, the better the outcome. Managing animal bites requires a multidisciplinary approach as the bite may occur on any part of the body. There should be no hesitancy in consulting with the appropriate specialist if the bite is on the eyes, nose, hands, genitals or the scalp. Several guidelines exist on managing specific animal bites like the dog, cat, snake, scorpion, bees, ants or other wildlife. Healthcare workers who manage animal bites should be aware of the latest guidelines and be aware of the organisms and the antibiotics needed to manage such injuries. Since many animal bites are seen by the primary care provider or the emergency room, the first treatment is to ensure that the wound is irrigated and cleaned. Debridement of necrotic or dead tissue is the next step. If there is any doubt in the management, the injury is severe or to the hand, a consult should be made with a specialist. for example, serious injury from dog bites should always be managed by an interprofessional group of healthcare professionals [9][10] (Level lll).

Outcomes and Evidence

The majority of people with animal bites have an excellent outcome. However, injuries to the face, groin and hands can lead to high morbidity. The available literature reveals conflicting opinions on management and until evidence-based medical evidence is available, the treatment will remain empirical. [11](Level V)


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Bites, Animal - Questions

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A 17-year-old girl is bitten by a neighbor's pet dog. Except for pain, the wounds appear superficial and do not appear infected. The dog was recently vaccinated and belongs to a physician. What is the next step in the management of this patient?



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Which of the following is false regarding domestic animal bites?



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Animal bites likely to carry Pasteurella multocida are best treated with which antibiotic?



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An 8-year-old boy is bitten by the neighbor's pet dog. It is unclear if the dog is up to date on his vaccinations. The boy appears to have suffered several puncture wounds on his arm. What is the next step concerning rabies exposure in the management of this patient?



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A patient sustains a puncture to the right hand after a bite. Within 24 hours the hand is swollen, erythematous, and tender. There is scant serous discharge at the site of the wound. What is the most likely source of the puncture wound?



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Which of the following is the most common complication following a cat bite injury?



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Which statements regarding bites is not true?



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A patient is evaluated for a bite. The bite most likely to become infected is which of the following?



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What is the best treatment after a cat bite?



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What is the best antibiotic for the treatment of a cat bite?



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A 10-year-old male has sickle cell disease type SS for which he takes hydroxyurea and folic acid daily. He presents to the emergency department with complaints of a dog bite to his right lower extremity. His father states that the family just got a new puppy that they were playing with in the backyard. While playing the puppy nipped at the child's leg and caused a series of superficial abrasions. The father states that his son had some bleeding which was controlled with direct pressure at the time. He waited several hours before bringing his son to be seen. Currently, the child has no complaints. There are several scabbed abrasions to his right lower extremity on the exam without any signs or symptoms of infection or uncontrolled bleeding. What is the best management for this patient?



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A 69-year-old male presents 1 hour after a cat bite to the soft tissue of his hand. He has a history of coronary artery disease, hypertension, and hyperlipidemia that his primary care provider manages him for. He is allergic to penicillin. There are several small puncture wounds to the thenar eminence. He is neurovascularly intact, the wounds are hemostatic and have no signs or symptoms of infection. The wounds are thoroughly explored for foreign bodies, damage to underlying structures, and irrigated. What is the most appropriate antibiotic prophylaxis for this patient?



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A 28-year-old male is brought to the emergency department in custody of the police. He is suspected of being involved in a store robbery and upon being confronted by the police, he fled. A K-9 unit was released and successfully apprehended the individual who now has several puncture wounds to his left distal arm in the shape of a dog's jaw. He complains of severe pain and is repeatedly threatening to sue the police for brutality. He refuses to cooperate with an exam and exclaims loudly in pain on light palpation of the arm and passive extension of his finger. There is a firm, wooden feeling on deep palpation. Distal pulses are 2+. X-rays are read as negative for fractures and radiopaque foreign bodies. The wounds are thoroughly irrigated and explored without any other clinically relevant findings. What is the best next step in management?



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A 13-year old is seen in the emergency department after he was bitten on the calf by the neighbor's pet dog. The dog has no signs of rabies. The dog bit the boy after he threw a rock at it. The bite appears on the posterior right calf and measures about 4 mm. There is no induration, edema, or drainage. After cleaning the wound, what antibiotic should be administered to this child?



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A young male presents to the emergency department after a dog bite (see image below). Which of the following is true about this condition? Select all that apply.

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    Contributed by Steve Bhmji, MS, MD, PhD
Attributed To: Contributed by Steve Bhmji, MS, MD, PhD



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Bites, Animal - References

References

Khazaei S,Karami M,Veisani Y,Solgi M,Goodarzi S, Epidemiology of Animal Bites and Associated Factors with Delay in Post-Exposure Prophylaxis; A Cross-Sectional Study. Bulletin of emergency and trauma. 2018 Jul     [PubMed]
Amparo ACB,Jayme SI,Roces MCR,Quizon MCL,Mercado MLL,Dela Cruz MPZ,Licuan DA,Villalon EES 3rd,Baquilod MS,Hernandez LM,Taylor LH,Nel LH, The evaluation of Animal Bite Treatment Centers in the Philippines from a patient perspective. PloS one. 2018     [PubMed]
Holzer KJ,Vaughn MG,Murugan V, Dog bite injuries in the USA: prevalence, correlates and recent trends. Injury prevention : journal of the International Society for Child and Adolescent Injury Prevention. 2018 Jul 23     [PubMed]
Brandenburg WE,Levandowski W,Califf T,Manly C,Levandowski CB, Animal, Microbial, and Fungal Borne Skin Pathology in the Mountain Wilderness: A Review. Wilderness     [PubMed]
Ngugi JN,Maza AK,Omolo OJ,Obonyo M, Epidemiology and surveillance of human animal-bite injuries and rabies post-exposure prophylaxis, in selected counties in Kenya, 2011-2016. BMC public health. 2018 Aug 9     [PubMed]
Saverino KM,Reiter AM, Clinical Presentation, Causes, Treatment, and Outcome of Lip Avulsion Injuries in Dogs and Cats: 24 Cases (2001-2017). Frontiers in veterinary science. 2018     [PubMed]
Beyene TJ,Mourits MCM,Kidane AH,Hogeveen H, Estimating the burden of rabies in Ethiopia by tracing dog bite victims. PloS one. 2018     [PubMed]
Barbosa Costa G,Gilbert A,Monroe B,Blanton J,Ngam Ngam S,Recuenco S,Wallace R, The influence of poverty and rabies knowledge on healthcare seeking behaviors and dog ownership, Cameroon. PloS one. 2018     [PubMed]
Elizabeth Murray G, Examining evidence on dog bite injuries and their management in children. Nursing children and young people. 2017 Apr 11     [PubMed]
Seneschall C,Luna-Farro M, Controlling rabies through a multidisciplinary, public health system in Trujillo, La Libertad, Peru. Pathogens and global health. 2013 Oct     [PubMed]
Aziz H,Rhee P,Pandit V,Tang A,Gries L,Joseph B, The current concepts in management of animal (dog, cat, snake, scorpion) and human bite wounds. The journal of trauma and acute care surgery. 2015 Mar     [PubMed]

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