Clinical Topic A-Z Clinical Speciality

Bites - human and animal

Bites - human and animal
D001733Bites and Stings
Injuries
2012-01-01Last revised in January 2012

Bites - human and animal - Summary

Human bites are either:

Occlusal injuries (inflicted by actual biting), or

Clenched-fist injuries (sustained when a clenched fist hits a person's teeth, often during a fight, causing small wounds over the metacarpophalangeal joints). Clenched-fist injury is particularly prone to infection.

Dog bites characteristically involve puncture wounds from the canine teeth which anchor the victim whilst the other teeth bite, shear, and tear the tissues causing stretch lacerations.

Cats have fine, sharp teeth and, despite having a weaker bite than dogs, are capable of penetrating bone and joint capsules.

Dog bites are the most common mammalian bite. It has been estimated that:

Dog bites account for 60–90% of bites.

Cat bites account for 5–20% of bites.

Human bites account for 4–23% of bites.

Wound infection is the most common complication of bites, occurring in 2–30% of dog bites, 15–50% of cat bites, and 9–50% of human bites.

Less frequent complications include septicaemia, septic arthritis, and tenosynovitis. Tetanus can occur after an animal bite or human bite, especially if the wound contains devitalized tissue, dirt, and saliva. However, tetanus after a human bite is extremely rare.

Risk of infection is increased in:

People who are diabetic, asplenic, cirrhotic, or immunosuppressed; people who have had a mastectomy; or people who have lymphoedema after radiotherapy.

Hand wounds: up to 36% of dog bites and up to 80% of cat bites to the hand become infected.

The circumstances under which the bite occurred should be documented and the wound assessed. This includes asking about:

Who was bitten, and by whom (or what).

When the bite occurred.

Whether the skin was broken.

The nature of the bite.

Any risk factors for infection.

Existing infection or other medical conditions in both the biter and the person who has been bitten.

Tetanus status.

Managing a bite involves:

Removal of any foreign bodies (e.g. teeth) from the wound.

Encouraging a wound that has just occurred to bleed, unless it is already bleeding freely.

Thorough irrigation with warm, running water.

Advising appropriate analgesia (ibuprofen or paracetamol) for pain relief, if required.

For a human bite, prescribing prophylactic antibiotics if the wound is less than 72 hours old, even if there is no sign of infection.

For an animal bite, prescribing prophylactic antibiotics if the wound is less than 48 hours old and the risk of infection is high.

Seeking immediate advice from a consultant in infectious diseases for anyone considered to be at risk of HIV or hepatitis B.

Referring to A&E for further assessment and management if wound closure is necessary.

Considering the need for tetanus and rabies prophylaxis.

Have I got the right topic?

1months3060monthsBoth

This CKS topic covers the management of human and animal bites.

There are separate CKS topics on Insect bites and stings and Lacerations.

The target audience for this CKS topic is healthcare professionals working within the NHS in the UK, and providing first contact or primary health care.

How up-to-date is this topic?

How up-to-date is this topic?

Changes

Last revised in January 2012

February 2013 — minor update. The 2013 QIPP options for local implementation have been added to this topic [NICE, 2013].

October 2012 — minor update. The 2012 QIPP options for local implementation have been added to this topic [NPC, 2012].

January 2012 — revised. A literature search was conducted in October 2011 to identify evidence-based guidelines, UK policy, systematic reviews, and key RCTs published since the last revision of the topic. No changes to clinical recommendations have been made. Issued in January 2012.

Previous changes

July 2011 — minor update. More exact paracetamol dosing for children has been introduced by the Medicines and Healthcare products Regulatory Agency [MHRA, 2011]. Prescriptions have been updated to reflect the revised dosing. Issued in July 2011.

May 2011 — minor update. The 2010/2011 QIPP options for local implementation have been added to this topic [NPC, 2011]. Issued in June 2011.

March 2011 — topic structure revised to ensure consistency across CKS topics — no changes to clinical recommendations have been made.

August 2009 — minor update. Advice from the National Institute for Health and Care Excellence guideline on when to suspect child maltreatment has been added to this topic [NICE, 2009c]. Issued in August 2009.

January 2009 — minor update. Clarithromycin added as an antibiotic option if a person is allergic to penicillin, in line with advice from the Health Protection Agency [HPA and Association of Medical Microbiologists, 2008]. Link updated to Health Protection Agency Clinical Rabies Service document [HPA, 2008]. Issued in February 2009.

May 2008 — minor update to the text for animal bites, making it clearer that all cat bites require antibiotic prophylaxis. Issued May 2008.

November 2007 — minor update to the text for animal bites. CKS now recommends that specialist advice should be sought for children under 12 years old who require antibiotic treatment and are allergic to penicillin, because they are unable to receive a tetracycline. Issued in December 2007.

August 2007 — minor update to text to clarify that, if tetanus vaccination is required, a combined tetanus vaccination should be used. Minor rewording of the Clinical Summaries on Assessing a bite, Managing a human bite, and Managing a cat and dog bite. Issued in August 2007.

April to July 2007 — converted from CKS guidance to CKS topic structure. The evidence-base has been reviewed in detail, and recommendations are more clearly justified and transparently linked to the supporting evidence.

There are no major changes to the recommendations.

March 2004 — reviewed. Validated in May 2004 and issued in July 2004.

May 2001 — reviewed. Validated in July 2001 and issued in October 2001.

Update

New evidence

Evidence-based guidelines

No new evidence-based guidelines since 1 October 2011.

The HPA have published a leaflet on reducing the risk of infection from pet rodents:

HPA (2013) Reducing the risk of human infection from pet rodents. Health Protection Agency. www.hpa.org.uk [Free Full-text (pdf)]

HTAs (Health Technology Assessments)

No new HTAs since 1 October 2011.

Economic appraisals

No new economic appraisals relevant to England since 1 October 2011.

Systematic reviews and meta-analyses

No new systematic reviews or meta-analyses published since 1 October 2011.

Primary evidence

No new randomized controlled trials published in the major journals since 1 October 2011.

New policies

No new national policies or guidelines since 1 October 2011.

New safety alerts

No new safety alerts since 1 October 2011.

Changes in product availability

No changes in product availability since 1 October 2011.

Goals and outcome measures

Goals

To offer immediate first aid

To reduce the risk of infection

To treat any established infection

To achieve satisfactory wound healing with good cosmetic outcome

To prevent tetanus

To refer anyone at risk of contracting hepatitis or HIV for specialist advice

QIPP - Options for local implementation

QIPP - Options for local implementation

Non-steroidal anti-inflammatory drugs (NSAIDs)

Review the appropriateness of NSAID prescribing widely and on a routine basis, especially in people who are at higher risk of both gastrointestinal (GI) and cardiovascular (CV) morbidity and mortality (e.g. older patients).

If initiating an NSAID is obligatory, use ibuprofen (1200 mg per day or less) or naproxen (1000 mg per day or less).

Review patients currently prescribed NSAIDs. If continued use is necessary, consider changing to ibuprofen (1200 mg per day or less) or naproxen (1000 mg per day or less).

Review and, where appropriate, revise prescribing of etoricoxib to ensure it is in line with MHRA advice and the NICE clinical guideline on osteoarthritis [CSM, 2005; NICE, 2008].

Co-prescribe a proton pump inhibitor (PPI) with NSAIDs for people with osteoarthritis, rheumatoid arthritis, or low back pain (for people over 45 years) in accordance with NICE guidance [NICE, 2008; NICE, 2009a; NICE, 2009b].

Take account of drug interactions when co-prescribing NSAIDs with other medicines (see Summaries of Product Characteristics). For example, co-prescribing NSAIDs with ACE inhibitors or angiotensin receptor blockers (ARBs) may pose particular risks to renal function; this combination should be especially carefully considered and regularly monitored if continued.

Antibiotic prescribing — especially quinolones and cephalosporins

Review and, where appropriate, revise current prescribing practice and use implementation techniques to ensure prescribing is in line with Health Protection Agency (HPA) guidance.

Review the total volume of antibiotic prescribing against local and national data.

Review the use of quinolones and cephalosporin prescribing against local and national data.

[NICE, 2013]

Background information

Definition

What is it?

Characteristics of a dog bite

What are the characteristics of a dog bite?

Dog bites characteristically involve puncture wounds from the canine teeth which anchor the victim whilst the other teeth bite, shear, and tear the tissues causing stretch lacerations [Dire, 1992; Morgan and Palmer, 2007]:

Lacerations occur in 30–45% of cases.

Puncture wounds occur in 13–34% of cases.

Superficial abrasions occur in 30–43% of cases.

Pit bull terriers inflict the most serious injuries as they have a biting force of up to 450 pounds per square inch (enough to crush sheet metal) and grind their molars into soft tissue, causing particularly large wounds and significant devitalization [Morgan, 2005].

The majority of dog bites are caused by pet male dogs (i.e. owned rather than strays), and their victims are more likely to be male and under 20 years of age [Wright, 1990; Sacks et al, 1996].

Children are usually bitten on the face, and up to 80% present with facial and cervical injuries: the majority affect the lips, nose, and cheeks. Adults tend to be bitten on the extremities, particularly the hands [Griego et al, 1995; Morgan, 2005].

Most attacks are unprovoked. Dogs resent their territory being invaded or being disturbed during eating, and dislike being threatened. They may also be jealous of attention given to other family members [Morgan and Palmer, 2007].

All dogs should be considered to have the potential to bite, but the highest risk appears to be from german shepherd dogs, pit bull terriers, rottweilers, and chows [Morgan and Palmer, 2007].

Characteristics of a cat bite

What are the characteristics of a cat bite?

Cats have fine, sharp teeth and, despite having a weaker bite than dogs, are capable of penetrating bone and joint capsules [Dire, 1992; Smith et al, 2000].

Puncture wounds occur in 57–86% of cases.

Lacerations occur in in 5–17% of cases.

Superficial abrasions occur in 9–25% of cases.

In a study in Dallas of 623 cat bites recorded in 1985 [Wright, 1990]:

The majority of cat bites were by stray female cats.

Their victims were most likely to be adult women.

People were bitten by their own cat in only 21% of cases.

In adults over the age of 25 years, 90% of bites were on the upper limb especially the finger and hand.

In children under the age of 5 years, 33% of bites were to the neck, face, or multiple locations.

Characterisics of a human bite

What are the characteristics of a human bite?

Human bites are either [Monteiro, 1995; Smith et al, 2000; Taplitz, 2004]:

Occlusal injuries (inflicted by actual biting), or

Clenched-fist injuries (sustained when a clenched fist hits a person's teeth, often during a fight, causing small wounds over the metacarpophalangeal joints). Clenched-fist injury is particularly prone to infection.

Most adult human bites (60–75%) occur on the hand [Griego et al, 1995; DTB, 2004]:

Men are most frequently bitten on the hand, arm, and shoulder.

Women are most frequently bitten on the breast, genitalia, leg, and arm.

Most human bites occur during fights, although accidental bites associated with sports, school activities, and sexual activity also occur [Griego et al, 1995; Taplitz, 2004].

Prevalence

How common are bites?

The incidence of mammalian bites is difficult to determine. It is estimated that 175–740 per 100,000 people a year in Europe and the United States are bitten by dogs, but only a minority seek medical attention [Wolff, 1998; Morgan and Palmer, 2007].

Dog bites are the most common mammalian bite [Wolff, 1998; Morgan, 2005]. It has been estimated that [Dire, 1992; Monteiro, 1995; Taplitz, 2004]:

Dog bites account for 60–90% of bites.

Cat bites account for 5–20% of bites.

Human bites account for 4–23% of bites.

The incidence of bites by other animals is very small. A study in Italy aimed to estimate the incidence of mammalian bites by examining the records of all people with bites (n = 1509) seen at the emergency department of two main hospitals in Bologna over 3 years. The incidence of bites from pets other than dogs and cats (for example rabbits, guinea pigs, hamsters) was very small (2.3%) and the incidence of bites from animals that live in close association with humans (for example rats, mice) was 1.1% [Ostanello et al, 2005].

The majority of victims are children, and boys are bitten more often than girls. Children are commonly bitten by a household pet [Brogan et al, 1995; Morgan and Palmer, 2007].

A recent telephone survey of 1184 families in Belgium found that the annual incidence of dog bites in children under the age of 15 years was 2.2% [De Keuster et al, 2006].

Severe dog bites occur most frequently in children younger than 5 years of age [Brogan et al, 1995].

The incidence of human bites in a daycare nursery for children under 3 years of age was estimated at 1.5 per 100 child-days of attendance with only 2% of bites breaking the skin [Infectious Diseases and Immunization Committee, 1998].

Complications and prognosis

Complications

Wound infection is the most common complication, occurring in 2–30% of dog bites, 15–50% of cat bites, and 9–50% of human bites [Baker and Moore, 1987; Dire, 1992; Cummings, 1994; Monteiro, 1995]. This compares with an infection rate of 1–12% of non-bite wounds managed in an Accident and Emergency department [Cummings, 1994].

There may be increased anxiety after a bite injury in both children and adults [De Keuster et al, 2006; Villani, 2006]:

Children may have nightmares in which they relive the event.

Children who have suffered severe and multiple dog bites are at risk of developing post-traumatic stress disorder.

Permanent scarring and disfigurement may lead to depression and decreased self-esteem.

Less frequent complications include septicaemia, septic arthritis, tenosynovitis, fractures, osteomyelitis, peritonitis, endocarditis, endophthalmitis, meningitis, and disfiguring wounds from severe mauling [Dire, 1992]. Tetanus can occur after an animal bite or human bite, especially if the wound contains devitalized tissue, dirt, and saliva [HPA, 2005b; Richardson, 2006]. However, tetanus after a human bite is extremely rare [Morgan, 2005].

Sexually-motivated human bites may present late due to embarrassment, and serious complications including streptococcal toxic shock syndrome, Fournier's gangrene, genital ulcers, and syphilis have been reported after penile bites [Morgan, 2005].

Bites and maulings by dogs are occasionally fatal: such injuries usually involve the head and neck and result in exsanguination from a major blood vessel:

The highest mortality is in sleeping neonates and babies who are usually bitten by household pets [Griego et al, 1995; Sacks et al, 1996; Presutti, 2001].

Fatalities are particularly associated with attacks by pit bull terriers, rottweilers, and German shepherd dogs [Sacks et al, 1996].

Rabbit and guinea pig bites. CKS found few literature reports of bites by these popular household pets. There are a few case reports:

Rabbit bites: five children sustained significant finger-tip injuries (two amputations and one partial amputation) after they had been left unsupervised and pushed a finger into the cage of their pet rabbit [Rubinstein and Wallis, 1994].

Guinea pig bites: there are case reports of severe infection with Pasteurella [Lion et al, 1995] and Haemophilus influenzae [Rolle, 2000] following guinea pig bites.

Specific to human bite

What complications are specific to a human bite?

There is a risk of infection from blood-borne viruses, hepatitis B, hepatitis C, and HIV. Compared with an inoculation injury, the risk is believed to be small — the risk for transmitting hepatitis C and HIV from a bite is at least 20 times less than the risk with an inoculation injury [Morgan, 2005].

Syphilis has been reported following a human bite [Fleisher, 1999].

Diseases resulting from an animal bite

What other diseases may result from an animal bite?

Dog bite

Rabies is an invariably fatal encephalomyelitis caused by the classical rabies virus, which is a lyssavirus and a member of the rhabdovirus family [McKay and Wallis, 2005]:

Rabies is usually spread to humans by bites. Cases of rabies after scratches, abrasions, or the licking of open wounds or mucous membranes by infected animals, are extremely rare. The risk of rabies after a bite by a rabid animal (5–80%) is about 50 times the risk of contracting rabies after a scratch (0.1–1%) from the same animal [Fishbein and Robinson, 1993].

Rabies is not endemic in the UK amongst terrestrial animals but rabies may result from a bite received abroad, usually from a dog, but other terrestrial animals (such as cats, foxes, jackals, wolves, mongooses, raccoons, skunks) may also carry the virus. Bats in the UK may also be rabid [Fishbein and Robinson, 1993].

The incubation period varies widely. It is usually between 30 and 90 days although it may be as short as 15 days in cases of bites to the head or neck [McKay and Wallis, 2005].

There have only been 20 cases of rabies in England and Wales since 1946: all but one person contracted the disease overseas. The exception was a death in Scotland in 2002 following a bite from a bat [HPA, 2005a; McKay and Wallis, 2005].

Capnocytophaga canimorsus (part of the normal canine oral flora but also occasionally isolated from cat bite wounds) has been associated with severe infections in immunocompromised people, which may result in meningitis, endocarditis, renal failure, and septicaemia [Smith et al, 2000].

Occasionally cat-scratch disease may also be caught from dog bites.

Cat bite

Cat-scratch disease is caused by Bartonella henselae and may follow a bite or scratch from a cat or dog. Cat-scratch disease presents with a primary erythematous papule 3–14 days after the injury, followed by lymphadenopathy and symptoms including fever, malaise, headache, and poor appetite. Lymph glands near the scratch become swollen (this may take up to 50 days to become evident), and swelling may persist for several months. Cat-scratch disease is usually mild and self limiting [Smith et al, 2000; Bower, 2001; HPA, 2006d].

Capnocytophaga canimorsus has occasionally been isolated from cat bite wounds.

Rat bite

Rat bite fevers include:

Streptobacillus moniliformis infection, occurring up to 10 days after the bite. There is an abrupt onset of fever, headache, vomiting, and severe migratory arthralgias and myalgias. Within 2–4 days a maculopapular or petechial rash develops over the extremities, palms, and soles. Skin lesions may become purpuric or confluent and may peel. An asymmetric polyarthritis or septic arthritis develops in 50% of people. Symptoms resolve over a few days if treated, but if not treated fever may persist for 1–2 weeks and arthritis for several weeks. Severe infection may lead to severe complications including pneumonia, metastatic abscess formation, and myocarditis [Washburn, 1995a; Warrell, 2003].

Spirillum minor, developing 1–4 weeks after the bite and characterised by fever, chills, headache, and malaise. The healed wound becomes inflamed and swollen and may break down to become suppurative or necrotic. There is a reddish-brown or violaceous rash over the extremities. Arthritis and myalgias may occur. Spontaneous cure is usually within 1–2 months. The commonest severe complication in untreated people is endocarditis [Washburn, 1995b; Warrell, 2003].

Other diseases transmitted by rat bites include lymphocytic choriomeningitis, tularaemia, rabies, leptospirosis, [Gollop et al, 1993] plague, and murine typhus.

Bat bite

Very rarely rabies may be caught from a bat in the UK and bat workers are most at risk. Rabies may be caused by the European bat lyssavirus type 1 or 2 (which infects insectivorous bats in Europe), an Australian bat lyssavirus, and the African Duvenhage virus [McKay and Wallis, 2005]:

A very small proportion of bats in the UK carry the European Bat Lyssavirus which may cause rabies [HPA, 2007].

The risk from these viruses is likely to be low because the incidence of acute infection and excretion of virus is rare in bats and because humans are rarely exposed to the most affected bat species (in the UK this is the Daubenton's bat) [HPA, 2007].

In 2002 two thousand UK bats were analysed and only two were found to be EBL positive (both Daubenton bats) [McKay and Wallis, 2005].

There was a death in Scotland in 2002 when an unvaccinated bat conservationist, who did not receive post-exposure prophylaxis after being bitten by a bat, died from rabies due to European Bat Lyssavirus type 2 [HPA, 2005a; McKay and Wallis, 2005].

Prognosis

It is estimated that approximately 80% of all bite wounds are minor, often ignored, and seldom require medical attention [Goldstein, 1992; Smith et al, 2000].

However, the potential for disfigurement or infection is great and directly correlates with a lack of proper medical attention and inadequate wound care [Smith et al, 2000]. Cat-bite injuries, particularly to the hand, can be devastating in terms of infection and permanent disability, if not treated appropriately [Mitnovetski and Kimble, 2004].

Risk factors for infection

What are the risk factors for infection?

People factors:

People who are diabetic, asplenic, cirrhotic, or immunosuppressed, who have had a mastectomy, or who have lymphoedema after radiotherapy, are at increased risk of wound infection [Dire, 1992; Monteiro, 1995; Smith et al, 2000; Morgan and Palmer, 2007].

People who are asplenic or who have cirrhosis of the liver have an increased risk of being infected with Capnocytophaga canimorsus [Smith et al, 2000; Morgan and Palmer, 2007].

People aged 50 years or over are more likely to get a wound infection following a bite [Griego et al, 1995].

Wound factors:

Hand wounds are more likely to become infected: up to 36% of dog bites and up to 80% of cat bites to the hand become infected [Morgan, 2005].

Risk of infection is also particularly high in [Griego et al, 1995; Morgan and Palmer, 2007]:

Wounds more than 6 hours old.

Previously-sutured wounds.

Puncture wounds.

Full-thickness wounds.

Wounds with devitalized tissue.

Wounds involving joints, tendons, ligaments, or fractures.

Wounds in the foot or over a joint.

Wounds on the scalp or face of an infant.

Crush injuries.

Management

Management

Scenario: Assessing a bite : covers the assessment of human and animal bites.

Scenario: Managing a human bite : covers the management of a human bite.

Scenario: Managing a cat or dog bite : covers the management of cat and dog bites.

Scenario: Advice on rabies risk : covers what advice to give to people who are at risk of rabies from being bitten due to their occupation or travel.

Scenario: Assessing a bite

Scenario: Assessing a bite

1months3060monthsBoth

Assessing someone with a human bite

How should I assess someone with a human bite?

Document how and when the bite occurred.

Examine the bite, and document its location, appearance, and any damage to underlying structures (for example arteries, nerves, tendons, joints). For a bite affecting the hand also document whether it is an occlusal injury inflicted by actual biting, or a clenched fist injury.

Determine whether the person is at increased risk of the wound becoming infected, either due to the nature of the bite or due to a medical condition (for example diabetes, immunosuppressed status).

Assess whether the wound is infected. The following may be present: redness, swelling, serosanguinous or purulent discharge, pain, localized cellulitis, lymphadenopathy, or fever.

Assess tetanus status, drug history and any known allergies.

Assess whether there is a risk of acquiring a blood-borne viral infection (for example hepatitis B or C, or HIV).

In most cases the status of the biter will not be known and it is often not practical to obtain a blood sample for testing. There is a higher risk of acquiring a blood-borne virus if:

The biter is known to be HIV positive, hepatitis B surface antigen (HBsAg) positive, or hepatitis C positive.

The biter is likely to be a high risk person, such as an intravenous drug user.

If the biter has not been tested for blood-borne virus infection then treat their status as unknown unless there is a very good reason to do otherwise (for example they have an AIDS-defining illness).

If the risk of a blood-borne virus infection is assessed as significant, then urgent post-exposure prophylaxis will be needed (see Managing risk of a viral infection) and further follow-up tests will be needed. See Testing for seroconversion of virus for more information.

Assess the status of the person who has been bitten:

Ask if they are known to be HIV positive, hepatitis B surface antigen (HBsAg) positive, or hepatitis C positive.

Check their vaccination status for hepatitis B.

It is essential to obtain an X-ray in people with the following:

Clenched fist injuries to exclude the presence of teeth or dental fragments, and rule out bone damage.

Crush injuries, suspected fracture, the possibility of a foreign body in the wound.

Although rare, suspect child maltreatment if there is a report or appearance of a human bite mark that is thought unlikely to have been caused by a young child.

Additional information

Additional information

Assess and document under what circumstances the bite occurred:

Who was bitten, and by whom.

When the bite occurred.

Whether the skin was broken.

The nature of the bite (i.e. occlusal or clenched fist).

Any risk factors for infection.

Consider existing infection or other medical conditions in both the biter and the person who has been bitten.

Tetanus status.

Note and document the following [Griego et al, 1995; Taplitz, 2004; HPA, 2005b; Morgan and Palmer, 2007] (record both positive and negative findings as there may be future litigation) [Taplitz, 2004]:

The location of the wound. Photographs or diagrams may be useful.

The size and depth of the injury.

The type of wound (for example penetrating or crush injury).

The degree of crush injury, devitalized tissue, nerve or tendon damage, and involvement of bones, joints, or blood vessels.

The range and movement of any adjacent joints.

The presence or absence of signs of infection.

Any lymphadenopathy.

The presence of any foreign bodies (for example teeth).

Any signs of infection.

Facial bites: perform an intraoral examination to exclude cheek lacerations with an intraoral communication [Morgan, 2005].

Basis for recommendation

Basis for recommendation

These recommendations are based on advice from the Health Protection Agency [HPA, 2005b] and expert opinion on the management of bites [Griego et al, 1995; Taplitz, 2004; Morgan, 2005].

The recommendation on considering risk of blood borne viruses is based on advice from the Health Protection Agency [HPA, 2005b] and expert opinion in a review article [Brook, 2005].

The recommendation on when to suspect child maltreatment is based on advice from the National Institute for Health and Clinical Excellence [NICE, 2009c].

Assessing someone with an animal bite

How should I assess someone with an animal bite?

Document how and when the bite occurred.

Examine the bite, and document its location, appearance, and any damage to underlying structures such as arteries, nerves, tendons, or joints.

Determine whether the person is at increased risk of the wound becoming infected, either due to the nature of the bite, or due to a medical condition (for example diabetes, immunosuppressed status).

Assess whether the wound is infected. The following may be present: redness, swelling, serosanguinous or purulent discharge, pain, localized cellulitis, lymphadenopathy, fever.

Assess tetanus status, drug history and any known allergies.

Assess the risk of acquiring rabies.

Send cultures for aerobic and anaerobic bacteria if the wound appears to be infected. Take samples from the deepest part of the wound, after topical decontamination, but before cleaning it thoroughly.

It is essential to obtain an X-ray in people with the following:

Penetrating scalp injuries in children. A small scalp puncture wound may indicate anchoring of teeth to the cranium during shaking, and it is important to identify underlying cranial injury or facial fractures.

Crush injuries, suspected fracture, foreign body.

Although rare, consider the possibility of child neglect if there is a report or appearance of an animal bite on a child who has been inadequately supervised.

Additional information

Additional information

Assess and document under what circumstances the bite occurred:

When, and in what country the bite occurred.

What sort of animal bit the person?

Was the attack provoked?

Was the animal domestic or wild?

The nature of the bite — its site, number, depth, and amount of tissue destruction.

Any risk factors for infection.

Does the person have any other medical conditions?

What is the tetanus status of the person?

Record both positive and negative findings as there may be future litigation [Taplitz, 2004], including [Griego et al, 1995; Taplitz, 2004; Morgan and Palmer, 2007]:

The location of the wound. Photographs or diagrams may be useful.

The size and depth of the injury.

The type of wound (for example penetrating or crush injury).

The degree of crush injury, devitalized tissue, nerve or tendon damage, and involvement of bones, joints, or blood vessels.

The range and movement of any adjacent joints.

The presence or absence of signs of infection.

Any lymphadenopathy.

The presence of any foreign bodies (for example teeth) in the wound.

Any signs of infection.

Facial bites: perform an intraoral examination to exclude cheek lacerations with an intraoral communication [Morgan, 2005].

Assess the risk of rabies:

In which country was the person bitten?

If the person was bitten in the UK there is no risk of rabies unless the bite was from a bat.

If the person was bitten abroad use the Health Protection Agency country by country risk chart (pdf). Note that the origin of the animal is important. Was the animal non-indigenous or recently imported? Was it a terrestrial animal or a bat?

What was the type of exposure?

Use the Health Protection Agency Duty Doctor Rabies protocol (pdf), taking into account the site and severity of the exposure, whether the bite/scratch was provoked, the current state of health of the animal (if known), and its ownership. Determine the tetanus and rabies immunization status of the dog or cat, if known. People are at risk not only if they have sustained major bites, but also if they have had minor bites (for example bites through clothed areas of the arms, trunk, or legs), licks to the mucosa, or licks to non-intact skin (for example if there are scratches or abrasions).

What is the immune status of the person bitten?

Ask whether the person had a primary course of rabies vaccination or any boosters in the past, and if so when this was.

Basis for recommendation

Basis for recommendation

The basis for this recommendation is advice from the Health Protection Agency Centre for Infections [HPA, 2008], and expert opinion on the management of bites [Griego et al, 1995; Taplitz, 2004; Morgan, 2005; Villani, 2006; Morgan and Palmer, 2007].

Consider the possibility of rabies in anyone who has been bitten by a bat in the UK [HPA, 2006e].

Consider the risk of rabies in anyone who has sustained a bite or scratch from a dog or cat whilst abroad [de Medeiros and Saconato, 2003; HPA, 2008]. The main host is usually a dog (in 99% of all human deaths from rabies) but other hosts include foxes, coyotes, wolves, jackals, cats, skunks, raccoons, mongooses, bats, and other biting animals [WHO, 1999].

The recommendation on when to consider child neglect is based on advice from the National Institute for Health and Clinical Excellence [NICE, 2009c].

Scenario: Managing a human bite

Scenario: Managing a human bite

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Referring someone with a human bite

When should I refer someone with a human bite?

Refer to secondary care:

Penetrating wounds involving arteries, joints, nerves, muscles, tendons, bones, or the central nervous system. Note: penetrating bites to the hands or feet are at particular risk of infection and serious complications.

Facial wounds (excluding very minor wounds).

Bites where there is a possibility of a foreign body (for example a tooth) in the wound.

Devitalized wounds where debridement is required.

Bites where the severity of the injury is difficult to assess.

People with severe cellulitis, or with infected bite wounds that are not responding to treatment, or who are systemically unwell.

People with an increased risk of infection — including those with diabetes or cirrhosis, those who are immunocompromised, and asplenic individuals (especially if they are not taking prophylactic penicillin).

Injuries requiring reconstructive surgery.

Bites to poorly vascularized areas such as ear cartilage/nose cartilage.

If adult bites have been inflicted on a child, consider child protection issues. Follow local policies for referral of children considered at risk.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published medical literature [Griego et al, 1995; Morgan, 2005].

Initial care of a human bite wound

How should a human bite wound be cared for initially?

If the wound has just occurred, encourage it to bleed, unless it is already bleeding freely.

Irrigate thoroughly with warm, running water.

Wound closure is rarely advised in primary care. For more information, see When to close a human bite wound.

Advise analgesia (paracetamol or ibuprofen) for pain relief, if required.

Prescribe prophylactic antibiotics for for all human bite wounds under 72 hours old, even if there is no sign of infection.

Consider if tetanus prophylaxis is required.

Where body tissue has been torn off as a result of a bite, wrap any torn off parts (for example part of an ear) in clean tissue and store in a plastic bag surrounded by ice for transport to hospital.

Management does not typically include reapplication of removed tissue.

Seek immediate advice from a consultant in infectious diseases for anyone considered to be at risk of HIV or hepatitis B. For more information, see Managing risk of a viral infection.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published medical literature [HPA, 2005b].

The wound should be irrigated thoroughly to remove dirt and bacteria and to minimize the risk of infection.

Antiseptic cleansers are not necessary and there is some concern that they damage tissue and delay wound healing [Hollander and Singer, 1999].

If a bite is 72 hours old and there is no sign that it has become infected, the risk of infection is likely to be low and prophylactic antibiotics are probably not of value. 

When to close a human bite wound

When should I close a human bite wound?

Bite wounds suitable for management in primary care do not usually require closure.

Referral to Accident and Emergency for further assessment and management is usually indicated if wound closure is thought to be necessary.

If referral to Accident and Emergency is not possible, the types of wounds that may be considered for closure include:

Fresh bite wounds (for example less than 6 hours old) where there are no risk factors for infection.

Bite wounds which are between 6 and 24 hours old where there are no risk factors for infection. However this is controversial and currently there is no consensus of opinion.

Allow the following bite wounds to heal without formal closure:

Bite wounds over 24 hours old.

Infected bite wounds.

Deep puncture wounds.

Bites to the hands and feet.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published medical literature [DTB, 2004; Taplitz, 2004; Brook, 2005; Richardson, 2006; Kravetz, 2007]. Wound closure is a controversial issue. CKS did not identify any randomized controlled trials or systematic reviews that assessed primary closure or delayed closure for human bites, however:

There is general agreement that infected wounds and those first seen more than 24 hours after the bite occurred should be left open.

Some experts recommend consideration of wound closure after irrigation and debridement in patients presenting less than 6 hours after the injury if there is no visible evidence of infection.

For bite wounds in anatomic regions where there are significant cosmetic concerns, such as the face, a primary closure approach by a plastic surgeon or other expert is often undertaken to prevent significant scarring.

Wounds with a high risk of complications or infection, such as hand wounds, are generally left open even in patients who present early. When closure is deemed appropriate, wound edges can be approximated but must still allow for drainage. If a joint or tendon is thought to be involved refer to orthopaedics or plastic surgery.

When to give tetanus prophylaxis

When should I give tetanus prophylaxis?

Give tetanus prophylaxis as follows:

Person fully immunized, i.e. has received five doses of vaccine at appropriate intervals: tetanus booster not needed. Consider giving human tetanus immunoglobulin for tetanus-prone wounds where the risk of infection is especially high, for example those contaminated with manure or extensive devitalized tissue.

Primary immunization complete, boosters incomplete but up-to-date: tetanus booster not needed but may be given if booster is due and it is convenient to give now. Consider giving human tetanus immunoglobulin for tetanus-prone wounds where the risk of infection is especially high, for example those contaminated with manure or extensive devitalized tissue.

Primary immunization incomplete, or boosters not up-to-date: give tetanus booster and further doses as needed to complete the recommended schedule (note: if the primary course is interrupted it should be resumed but not repeated). Add human tetanus immunoglobulin if it is a tetanus-prone wound (defined as: a puncture wound; a significant degree of devitalized tissue; contaminated with soil or manure; containing foreign bodies; compound fractures; clinical signs of sepsis; wounds or burns sustained more than 6 hours before surgical treatment). Note: inject tetanus vaccine and immunoglobulin at different sites.

Not immunized or immunization status uncertain: give an immediate dose of vaccine. Add human tetanus immunoglobulin if it is a tetanus-prone wound (see above). Arrange further doses of tetanus vaccine as needed to complete the recommended five-dose schedule.

A total of five doses of tetanus vaccine, administered at the appropriate intervals, is considered to give lifelong immunity.

Vaccinate the person with a combined tetanus vaccine for example tetanus/diphtheria/inactivated polio vaccine, as tetanus vaccine is only available in a combined preparation.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the Department of Health [DH, 2006a].

Managing risk of a viral infection

How should I manage someone who may be at risk of a blood-borne viral infection?

Seek immediate advice from a consultant in infectious diseases for anyone considered to be at risk of HIV or hepatitis B. Consider all people to be at risk unless the current status of the biter is known (rare).

If post-exposure prophylaxis (PEP) is needed:

PEP for HIV should be started at soon as possible.

Seek advice about the most appropriate PEP regimen for hepatitis B, see Table 1.

Reassure the person that the risk of acquiring hepatitis or HIV from a bite is very small, even if the assailant is known to be infected.

Arrange sequential testing to check for seroconversion (see Testing for seroconversion of virus).

Table 1 . Hepatitis B vaccine prophylaxis for significant exposure (e.g. a bite from a high risk individual).
Hepatitis B vaccination status of person exposed HBsAg positive source HBsAg status unknown HBsAg negative source
Unvaccinated Give an accelerated* or hyperaccelerated course of hepatitis B vaccine and one dose of hepatitis B immunoglobulin Give an accelerated or hyperaccelerated course of hepatitis B vaccine Initiate course of hepatitis B vaccine
Received one dose of hepatitis B vaccine pre-exposure Give an accelerated* or hyperaccelerated course of hepatitis B vaccine and hepatitis B immunoglobulin Give an accelerated or hyperaccelerated course of hepatitis B vaccine Finish course of hepatitis B vaccine
Received two or more doses of hepatitis B vaccine Give one dose of hepatitis B vaccine followed by one dose one month later Give one dose of hepatitis B vaccine Consider booster dose of hepatitis B vaccine
Known responder to hepatitis B vaccine (anti HBs > 10 miU/mL) Consider booster dose of hepatitis B vaccine Consider booster dose of hepatitis B vaccine Consider booster dose of hepatitis B vaccine
Known non responder to hepatitis B vaccine (anti HBs < 10 miU/mL 2–4 months post immunization) Give one dose of hepatitis B immunoglobulin and consider giving a booster dose of hepatitis B vaccine Give one dose of hepatitis B immunoglobulin and consider giving a booster dose of hepatitis B vaccine Consider giving a booster dose of hepatitis B vaccine. Do not give a course of hepatitis B immunoglobulin
* An accelerated course of vaccine consists of doses spaced at 0, 1, and 2 months. A booster dose may be given at 12 months to those at continuing risk of exposure to HBV. † A hyper-accelerated course of vaccine may be offered by some Occupational Health Departments. This consists of doses at 0, 7, and 21 days with booster dose at 6 or 12 months.
Data from: [HPA, 2005b]

Additional information

Additional information

It is usually very difficult to assess whether or not a person is at risk of contracting HIV, or hepatitis B or C. For information on how to assess whether the person who has been bitten is at risk of acquiring a blood-borne virus, see Assessing someone with a human bite. Always err on the side of caution and seek immediate advice from a specialist if you consider there is any risk of infection.

In people who are at high risk of a blood-borne virus infection, explain that it is important to take blood to store in the laboratory in case future follow-up tests are positive.

When taking blood from a person who is at high risk of a blood-borne virus infection:

Explicit valid consent from the person, or from their legal representative if appropriate, should be obtained before the test. Consent is needed both for taking and testing blood, and for checking results against archived samples.

Obtain a 10 mL clotted sample from the person who has been bitten for archiving in the laboratory.

Where practical, a sample should be obtained from the biter for testing for hepatitis B surface antigen (HBsAg), HIV, and hepatitis C.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the Health Protection Agency [HPA, 2005b].

The risk of transmission of HIV from a human bite is unknown but is likely to be small [HPA, 2005b]. In the rare cases when HIV transmission has occurred, bloody saliva has been present [Morgan, 2005]. Many reports are case studies [Vidmar et al, 1996; Khajotia and Lee, 1997; Pretty et al, 1999]. The risk is likely to be increased if [Pretty et al, 1999]:

Blood is present in the oral cavity.

The bite breaks the skin.

The bite is associated with a previous injury.

The biter had a deficiency in anti-HIV salivary elements.

There are case reports that hepatitis B may be transmitted by a human bite [Stornello, 1991; Hui et al, 2005].

There are case reports suggesting that hepatitis C may be transmitted by a human bite [Dusheiko et al, 1990; Figueiredo et al, 1994]. The Health Protection Agency states that hepatitis C appears to be transmitted more easily than HIV [HPA, 2005b].

Testing for seroconversion of virus

How do I test for seroconversion of a blood-borne virus?

Obtain valid consent for all tests.

If any of the tests are positive, seek advice from a consultant in infectious diseases for further management.

Blood should have been taken from the victim at the time of the incident and archived.

Table 1 . Testing for hepatitis C, hepatitis B, and HIV after potential exposure.
Time Hepatitis C Hepatitis B HIV
6 weeks Polymerase chain reaction (PCR) Surface antigen Antigen/antibody combined test
3 months Polymerase chain reaction (PCR) and antibody Surface antigen Antigen/antibody combined test
6 months Antibody Surface antigen (surface antibody)* Antigen/antibody combined test
* HB surface antibody only needed at 6 months if vaccination only started at injury.
Data from: [HPA, 2005b]

Basis for recommendation

Basis for recommendation

This recommendation is based on expert opinion from the Health Protection Agency [HPA, 2005b].

Treatment of infected human bite

How do I treat a human bite that has become infected?

Send pus or a deep wound swab for culture, before cleaning the wound. State on the form that the swab is from an infected human bite.

Treat empirically for 7 days with oral antibiotics.

Admit anyone who has a severe infection or who is systemically unwell as intravenous antibiotics may be required.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published literature [HPA, 2005b; Kravetz, 2007]. CKS found no good quality randomized controlled trials that assessed the use of antibiotics for people with infected wound bites. However they are generally believed to be effective.

Antibiotic choice for a human bite

Which antibiotic should I give to someone with a human bite?

For both prophylaxis and treatment of an infected human bite, prescribe a 7-day course of co-amoxiclav.

For people who are allergic to penicillin prescribe a 7-day course of:

Metronidazole plus doxycycline, or

Metronidazole plus erythromycin, or

Metronidazole plus clarithromycin.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion published in the medical literature [HPA, 2005b; HPA, 2006a].

There is limited evidence that antibiotics prevent infections after a human bite.

More than 42 different species of bacteria have been isolated from the human mouth, and up to 190 if gingivitis or periodontitis are present. The most common organisms in human bites include Streptococcus spp, Staphylococcus aureus, Haemophilus spp, Eikenella corrodens, and Bacteroides spp and other anaerobes. E. corrodens has been found in 25% of human bites to the hand [Smith et al, 2000; HPA, 2005b; Morgan, 2005].

Co-amoxiclav:

Co-amoxiclav is recommended because it is a broad-spectrum antibiotic and effective against the most commonly isolated organisms from human bites including alpha- and beta-haemolytic streptococci, S. aureus, S. epidermis, corynebacteria, and E. corrodens.

Metronidazole plus erythromycin or clarithromycin:

Metronidazole (in addition to tetracyclines or erythromycin) covers beta-lactamase-producing anaerobes.

Erythromycin has good activity against staphylococci and streptococci (the most common pathogens).

Clarithromycin may be more suitable if erythromycin cannot be tolerated due to adverse effects.

Follow up for person with human bite

What follow-up is needed for someone who has had a human bite?

This follow-up advice only applies to people who have not been referred to hospital.

If the bite wound is not infected — advise the person to check for signs of infection and if these develop to attend urgently for review.

If the wound is infected — review at 24 and 48 hours to ensure the infection is responding to treatment. Advise the person to attend urgently for review if the infection worsens or if they feel increasingly unwell.

For follow-up of people who are at high risk of a blood-borne virus, see Managing risk of a viral infection.

Basis for recommendation

Basis for recommendation

These recommendations are based on pragmatic advice and expert opinion from the Health Protection Agency [HPA, 2005b].

Scenario: Managing a cat or dog bite

Scenario: Managing a cat or dog bite

1months3060monthsBoth

Referring someone with animal bite

When should I refer someone with an animal bite?

Refer to secondary care:

Penetrating wounds involving arteries, joints, nerves, muscles, tendons, bones, or the central nervous system. Note: penetrating bites to the hands or feet are at particular risk of infection and serious complications.

Facial wounds (excluding very minor wounds).

Bites where there is a possibility of a foreign body (for example a tooth) in the wound.

Wounds which might benefit from closure.

Devitalized wounds where debridement is required.

Bites where the severity of the injury is difficult to assess.

People with severe cellulitis, or with infected bite wounds that are not responding to treatment, or who are systemically unwell.

People with an increased risk of infection — including those with diabetes or cirrhosis, those who are immunocompromised, and asplenic individuals (especially if they are not taking prophylactic penicillin).

Bites that might need reconstructive surgery.

Children with scalp wounds (for X-ray).

Bites to poorly vascularized areas eg ear cartilage/nose cartilage.

If an animal has bitten a child, consider the possibility of poor parenting and supervision. Follow local policies for referral of children considered at risk.

If there is a possibility that the person has been exposed to rabies, seek immediate advice from the Virus Reference Department of the Health Protection Agency. For more information see Managing someone at risk of rabies.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion [Griego et al, 1995; Morgan, 2005; Morgan and Palmer, 2007].

Initial care of animal bite

How should an animal bite be cared for initially?

If possible remove any foreign bodies (for example teeth) from the wound.

If the wound has just occurred encourage it to bleed, unless it is already bleeding freely.

Irrigate thoroughly with warm, running water.

Wound closure is rarely advised in primary care. For more information see When to close an animal bite wound.

Advise analgesia (ibuprofen or paracetamol) for pain relief, if required.

Prescribe prophylactic antibiotics if the wound is less than 48 hours old and the risk of infection is high.

Consider the need for tetanus prophylaxis.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published medical literature [HPA, 2005b; HPA, 2006c; Morgan and Palmer, 2007].

Although tetanus after animal bites is rare, all guidelines in common use advise tetanus prophylaxis, with immunoglobulin and toxoid to be administered to patients with a history of two or fewer immunizations.

Irrigation of the wound removes dirt and bacteria, minimizing the risk of infection.

There is no evidence to support irrigating a deep penetrating wound with normal saline using a needle or catheter, but it is common practice.

Antiseptic cleansers are not necessary, and there is some concern that they damage tissue and delay wound healing [Hollander and Singer, 1999].

When to close an animal bite wound

When should I close an animal bite wound?

Minor bite wounds suitable for management in primary care do not usually require closure.

Referral to Accident and Emergency for further assessment and management is usually indicated if wound closure is thought to be necessary.

The type of wounds that may be considered for closure include:

Fresh bite wounds (for example less than 6 hours old) where there are no risk factors for infection.

Bite wounds that present between 6 and 24 hours where there are no risk factors for infection. However this is controversial and currently there is no consensus of opinion.

Allow the following bite wounds to heal without formal closure:

Bite wounds over 24 hours old.

Infected bite wounds.

Deep puncture wounds.

Bites to the hands and feet.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published medical literature [DTB, 2004; Taplitz, 2004; Brook, 2005; Richardson, 2006; Kravetz, 2007]. Wound closure is a controversial issue. CKS identified one small randomized controlled trial that compared primary wound closure with leaving a bite wound open [Maimaris and Quinton, 1988]. There was no difference between the groups in the incidence of infection. However:

There is general agreement that infected wounds, and those first seen more than 24 hours after the bite, should be left open.

Some experts recommend consideration of wound closure, after irrigation and debridement, in patients presenting less than 6 hours after the injury, if there is no visible evidence of infection.

For bite wounds in anatomic regions where there are significant cosmetic concerns, such as the face, a primary closure approach by a plastic surgeon or other expert is often undertaken to prevent significant scarring.

Wounds with a high risk of complications or infection, such as hand wounds, are generally left open even in patients who present early. When closure is deemed appropriate, wound edges can be approximated but must still allow for drainage. If a joint or tendon is thought to be involved, an orthopaedic or plastic surgery consultation should be obtained.

Decision for antibiotic prophylaxis

Should I give antibiotic prophylaxis to someone with an animal bite?

Prescribe oral antibiotics for:

All cat bites, animal bites to the hand, foot, and face; puncture wounds; wounds requiring surgical debridement; wounds involving joints, tendons, ligaments, or suspected fractures.

Wounds that have undergone primary closure.

People who are at risk of serious wound infection (for example those who are diabetic, cirrhotic, asplenic, or immunosuppressed).

People with a prosthetic valve or a prosthetic joint.

Antibiotics are not generally needed if the wound is more than 2 days old and there is no sign of local or systemic infection.

Basis for recommendation

Basis for recommendation

These recommendations are based on published expert opinion [Dire, 1992; Cummings, 1994; Smith et al, 2000; HPA, 2006c; Morgan and Palmer, 2007].

Limited evidence from a Cochrane systematic review (only one randomized controlled trial used co-amoxiclav) suggests that antibiotic prophylaxis reduces the incidence of infections from cat bites, and from any type of bite wounds to the hand.

Antibiotic prophylaxis following animal bites should be employed selectively, being reserved for the bites most likely to become infected, such as when adequate debridement cannot be achieved, and in immunocompromised people at high risk of infection [HPA, 2006c].

High-risk patients with more justification for antibiotic prophylaxis include those with previous mastectomy, prosthetic joints, diabetes, immunosuppression, cirrhosis, steroid therapy, and splenectomy.

Treating an infected animal bite

How should I treat an animal bite that has become infected?

Send a pus or deep wound swab for culture (state on the form that the swab is from an infected animal bite).

Treat empirically with oral antibiotics for 7 days.

Admit anyone who has a severe infection or who is systemically unwell as intravenous antibiotics may be required.

Basis for recommendation

Basis for recommendation

These recommendations are based on expert opinion from the published literature [HPA, 2006c]. CKS found no good quality randomized controlled trials that assessed the use of antibiotics for people with infected bite wounds. However they are generally believed to be effective.

Antibiotic choice for an animal bite

Which antibiotic should I use for someone with an animal bite?

For prophylaxis and treatment of an infected animal bite, prescribe a 7–day course of co-amoxiclav.

For people who are allergic to penicillin, prescribe:

Metronidazole plus doxycycline, or

Metronidazole plus oxytetracycline.

For children under 12 years old who are allergic to penicillin, seek advice from a microbiologist.

Do not use erythromycin alone for prophylaxis or treatment of bite wounds.

For animals not covered in this guidance (for example pigs), seek specialist advice for the most appropriate antibiotic.

Basis for recommendation

Basis for recommendation

These recommendations are based on published expert opinion from the Health Protection Agency [HPA, 2006a].

Co-amoxiclav is recommended as it is a broad-spectrum antibiotic and effective against most bacteria isolated from domestic animal bites.

Doxycycline/oxytetracycline plus metronidazole are recommended as:

Doxycycline and oxytetracycline have good activity against Pasteurella species (the most common pathogen), staphylococci, and streptococci [Smith et al, 2000; Talan et al, 2003].

Metronidazole is active against beta-lactamase-producing anaerobes.

Most infections that develop from dog and cat bites are caused by several organisms, with a mean of 2.8 to 3.6 bacterial species per wound culture, including an average of one anaerobic species per wound [Griego et al, 1995].

One study of infected cat and dog bites found that the most commonly isolated bacteria was Pasteurella (57% of dog bites and 75% of cat bites). Other common aerobes included streptococci, staphylococci, moraxella, and neisseria. Common anaerobes included fusobacterium, bacteroides, porphyromonas, and prevotella [Talan et al, 1999].

Pasteurella multocida is a Gram-negative pathogen that causes a rapid intense inflammatory response [Morgan, 2005; HPA, 2006b; Morgan and Palmer, 2007]:

It is found in dogs, cats, rabbits, chickens, turkeys, cattle, swine, and rodents.

It is is the most likely pathogen in an infected bite by a dog or cat presenting within 12 hours of the bite.

Complications include abscesses, cellulitis, and joint infections.

If septicaemia develops, the mortality may be as high as 30%.

Rarely it may cause pneumonic or lung abscesses in people with underlying pulmonary disease.

It is resistant to erythromycin and flucloxacillin.

It may cause tenosynovitis in hand bites and may lead to irreparable damage and amputation.

Co-amoxiclav is recommended because it is effective against most bacteria isolated from domestic animal bites. Penicillin will not cover all Staphylococcus aureus infections, or infections caused by anaerobes.

Metronidazole (in addition to tetracyclines) covers beta-lactamase-producing anaerobes.

Erythromycin should never be used alone in treating bite wounds — more than 80% of P. multocida are resistant, and serious clinical failures including meningitis have been documented following erythromycin treatment.

Managing someone at risk of rabies

How should I manage someone at risk of contracting rabies?

Discuss the need for post-exposure prophylaxis urgently with the Virus Reference Department of the Health Protection Agency (HPA, telephone 020 8327 6017).

Manage according to the risk of rabies. The combination of human rabies immunoglobulin and rabies vaccine is recommended for bite exposure, regardless of the interval between exposure and initiation of treatment.

Everyone who has been bitten by a bat in the UK needs post-exposure prophylaxis urgently. The HPA advises that, to ensure consistency of advice: for all unequivocal exposures to bats (such as bites which are of a nature to be a possible rabies risk) post-exposure prophylaxis should be with rabies immunoglobulin and five doses of vaccine. If the exposure is uncertain (the person can not confirm a bite), then vaccination alone may be considered.

Complete a Rabies Advice Record Form (even if you decide that no treatment is required). Record the number of doses of human rabies immunoglobulin (if required) and the number of doses of vaccine required. Phone the Virus Reference Department (VRD) to verify the decision or if you require further advice. Send all completed forms to the Rabies secretary, VRD Office, by hand or fax to 020 8200 1569.

Basis for recommendation

Basis for recommendation

Discussing the need for post-exposure prophylaxis urgently

This recommendation is based on expert opinion from the Health Protection Agency [HPA, 2008].

Urgent post-exposure prophylaxis following bat bite in the UK

This recommendation is based on expert opinion from the Health Protection Agency [HPA, 2008].

Rabies Advice Record Form

This recommendation is based on expert opinion from the Department of Health [DH, 2006b].

Advice about avoiding future bites

What advice should I give about avoidance of future bites?

Advise the person to avoid:

Running or screaming in the presence of a dog, as dogs have a tendency to chase moving objects.

Greeting a dog with an outstretched hand.

Petting a dog without letting it sniff them first.

Humanising the dog (for example allowing it to sleep on the furniture, beg for food), and do not hug or kiss it, as this makes it more difficult for the dog to distinguish between animal and master, and may increase the risk of biting.

Basis for recommendation

Basis for recommendation

This advice is based on expert opinion from the published literature [Presutti, 2001].

Canine aggressiveness may stem from inadequate socialisation, fear, protection of territory, dominance behaviour, jealously, or over breeding [Brogan et al, 1995]:

Dominance aggression usually occurs in relation to people who are well known to the dog, and most often happens in familiar surroundings.

Stray dogs tend to be more wary and are less likely to be aggressive.

Follow-up for an animal bite

What follow-up is needed for someone who has had an animal bite?

This follow-up advice only applies to people who have not been referred to hospital (i.e. are being managed in primary care).

If the bite wound is not infected — advise the person to check for signs of infection and if these develop to attend urgently for review.

If the wound is infected — review at 24 and 48 hours to ensure the infection is responding to treatment. Advise the person to attend urgently for review if the infection worsens or if they feel increasingly unwell.

Follow-up for people who have needed post-exposure prophylaxis for rabies should follow the regimen advised for them by the Virus Reference Department of the Health Protection Agency. For more information, see Managing someone at risk of rabies.

Basis for recommendation

Basis for recommendation

This recommendation is based on what CKS considers to be good clinical practice.

Scenario: Advice on rabies risk

Scenario: Advice on rabies risk

1months3060monthsBoth

Occupational or travel rabies risk

What advice should I give to people at risk of rabies due to their occupation or travel?

Occupational risk: the following people who are at risk of being bitten due to their occupation should be offered pre-exposure vaccine, including rabies.

Those who, in the course of their work, regularly handle imported animals, for example at animal quarantine centres, zoos, research and acclimatization centres where primates and other imported animals are housed, ports (e.g. certain HM Revenue and Customs officers), and at the premises of carrying agents authorized to carry imported animals.

Veterinary and technical staff, including local authority dog wardens who are also inspectors.

People who regularly handle bats in the UK.

Those working abroad (e.g. veterinary staff or zoologists) who by the nature of their work are at risk of contact with rabid animals.

For a full list of people for whom pre-exposure vaccination is recommended see the Department of Health website, Immunizations against infectious disease.

Travellers at risk: pre-exposure immunization is also recommended for some travellers, including:

Those living in or travelling for more than one month to rabies-enzootic areas, unless there is reliable access to prompt, safe medical care.

Those travelling for less than one month to enzootic areas, but who may be exposed to rabies because of their travel activities, or those who would have limited access to post-exposure medical care.

For more information on the management of a person who has been bitten and is at risk of rabies, see Managing someone at risk of rabies in Scenario: Managing a cat or dog bite.

Basis for recommendation

Basis for recommendation

These recommendations are based on guidance from the Health Protection Agency and the Department of Health [DH, 2006b; HPA, 2006e; HPA, 2008].

Important aspects of prescribing information relevant to primary healthcare are covered in this section specifically for the drugs recommended in this CKS topic. For further information on contraindications, cautions, drug interactions, and adverse effects, see the electronic Medicines Compendium (eMC) (http://medicines.org.uk/emc), or the British National Formulary (BNF) (www.bnf.org).

Antibiotics in pregnancy/breastfeeding

Which antibiotics can I give to women who are pregnant or breastfeeding?

Pregnancy:

Co-amoxiclav and erythromycin may be given during pregnancy.

Metronidazole: despite theoretical safety concerns, a number of epidemiological studies have shown no conclusive evidence that metronidazole use during pregnancy causes an increased risk of malformations, stillbirths, or low birth-weight infants.

Tetracyclines are not suitable for use during pregnancy, as they are deposited in the teeth and bones of the developing fetus.

Breastfeeding:

Co-amoxiclav and erythromycin may be given to women who are breastfeeding.

Short courses (7 days) of doxycycline and oxytetracycline may be used during breastfeeding.

A single course (7 days) of oral metronidazole 200 mg or 400 mg three times a day may be used during breastfeeding.

[NTIS, 1999; Schaefer, 2001; UKMiCentral, 2004; BNF 55, 2008]

Issues prescribing antibiotics

Are there any other issues I need to be aware of before prescribing antibiotics?

Co-amoxiclav

Co-amoxiclav

Cholestatic jaundice may rarely occur during or shortly after the use of co-amoxiclav [CSM, 1997]. This is more common in men, in people over the age of 65 years, and with longer courses of treatment (over 14 days).

Metronidazole

Metronidazole

Common adverse effects include a metallic taste and gastrointestinal irritation (in particular nausea and vomiting). These are more common at higher doses.

Some people taking oral metronidazole experience disulfiram-like reactions to alcohol (flushing, increased respiratory rate, increased pulse rate). Although there is no conclusive evidence to support an interaction between metronidazole and alcohol, people taking metronidazole should be advised of the possible consequences of drinking alcohol [Baxter, 2006].

Erythromycin or clarithromycin

Erythromycin or clarithromycin

Common adverse effects include gastrointestinal disturbances (for example nausea, vomiting, diarrhoea), especially at higher doses. Gastrointestinal adverse effects are less common with clarithromycin than with erythromycin [BNF 55, 2008].

Erythromycin and clarithromycin can increase the plasma levels of certain other drugs (for example theophylline, carbamazepine) and can potentiate the effects of warfarin. A dose reduction may be required in these circumstances.

Advise the person to seek medical advice if symptoms of toxicity to these drugs occur during treatment with erythromycin or clarithromycin.

If a person is taking additional medication that may interact with erythromycin or clarithromycin, an alternative macrolide (azithromycin) may be considered [BNF 55, 2008].

If erythromycin or clarithromycin is taken with a statin, there is an increased risk of myopathy. Advise the person to stop the statin whilst the macrolide is being taken.

Tetracyclines

Tetracyclines

Tetracyclines should not be used in in children under 12 years of age, as they are deposited in the teeth and bones of the developing child.

Benign intracranial hypertension is a rare but important adverse effect of tetracyclines. If a person taking a tetracycline develops headache and visual disturbances, the tetracycline should be stopped.

Doxycycline may cause photosensitivity reactions: advise the person to avoid exposure to direct sunlight or to sunlamps.

Evidence

Evidence

Supporting evidence

Antibiotic prophylaxis

Evidence on antibiotic prophylaxis

Prophylactic antibiotics are effective for some bites. One systematic review found that that prophylactic antibiotics reduce the risk of infection after human bites. However a subsequent randomized controlled trial (RCT) found that antibiotic prophylaxis for low-risk human bites may not be necessary. There is no evidence that the use of prophylactic antibiotics is effective for cat or dog bites. There is evidence that the use of antibiotic prophylaxis after bites to the hand reduces infection, but confirmatory research is required.

A Cochrane review (search date: November 2000) identified eight RCTs (n = 522) that compared the use of an antibiotic with placebo or no treatment [Medeiros and Saconato, 2001]:

All studies assessed the use of antibiotics within 24 hours of the bite wound.

The populations were variable. Two studies included only children, two analyzed only adults, and three studies included both adults and children. One study did not specify an age group. All studies analyzed the incidence of infection. Four studies analysed the incidence of infection according to body part injured, three studies analyzed according to the type of wounds (lacerations, puncture, or avulsions).

In six studies the bites were caused by dogs, in one study bites were caused by cats, and in the other study the bites were caused by humans.

Several antibiotics were used as the intervention, including phenoxymethyl penicillin (two RCTs), oxacillin (two RCTs), dicloxacillin (two RCTs), co-trimoxazole (one RCT). In two studies a choice of antibiotic was given: cefalexin or erythromycin were used in one study; and ceclor, kefzol, or penicillin were used in another. Not all of these antibiotics may be appropriate for treating bites.

The results for the incidence of infection were as follows:

All bites. Pooled results from eight RCTs (n = 522) found that there was no difference between the rates of infections whether or not prophylactic antibiotics were used (OR 0.49, 95% CI 0.15 to 1.58).

Dog bites. Pooled results from six RCTs (n = 463) found that the infection rate was not reduced after the use of prophylactic antibiotics (4% [10/225]) compared with the control group (5.5% [13/238], OR 0.74, 95% CI 0.30 to 1.85).

Cat bites. One small study (n = 11) reported a lower infection rate in the treatment group who received prophylactic antibiotics (0% [0/5]) compared with the control group (67% [4/6]).

Human bites. Only one trial (n = 48) analyzed human bites, and the infection rate in the antibiotic group (0/33) was significantly lower than the infection rate in the control group (47% [7/15], OR 0.02, 95% CI 0.00 to 0.33).

The results for the site of the bite were:

Hand bites. Pooled results from three RCTs (n = 104) found that infection rates were significantly reduced by antibiotics (2% in the antibiotic group versus 28% in the control group) (OR 0.10, 95% CI 0.01 to 0.86; NNT = 4, 95% CI 2 to 50).

Head or neck bites. Pooled results from two RCTs (n = 82) found that infection occurred in only one patient in the control group, compared with no patients in the experimental group (OR 0.31, 95% CI 0.01 to 7.77).

Trunk bites. Pooled results from two RCTs found that infection was observed in only one patient in the experimental group and no patients in the control group (OR 1.80, 95% CI 0.04 to 79.4).

One subsequent small RCT (n = 127) compared a cefalexin/penicillin combination with placebo for preventing infection in low risk (penetrated only the epidermis and did not involve hands, feet, skin, overlying joints, or cartilaginous structures) human bites less than 24 hours old. Infection developed in 1 of 62 patients receiving placebo (1.6%, 95% CI 0.0 to 7.3%) and 0 of 63 patients receiving antibiotics (0%, 95% CI 0.0 to 4.6%). Antibiotic treatment of some low-risk human bite wounds could therefore be unnecessary since infection rates appear to be similar in low-risk human bite wounds whether treated with antibiotics or placebo [Broder et al, 2004].

Wound closure

Evidence on wound closure

CKS found no randomized controlled trials (RCTs) that assessed the incidence of bite-wound infection after delayed primary wound closure.

There is very limited evidence that primary wound closure influences the incidence of wound infection.

One small RCT compared primary closure of dog bite wounds (presenting within 24 hours) with leaving the wound open. Of 169 bite wounds assessed, 92 wounds were sutured and 77 were left open. All wounds were irrigated and debrided. No prophylactic antibiotics were given. There was no significant difference in the incidence of infection with closed wounds (7/92) compared with open wounds (6/77) (RR 0.98, 95% CI 0.33 to 2.62) [Maimaris and Quinton, 1988].

Search strategy

Scope of search

A literature search was conducted for guidelines, systematic reviews and randomized controlled trials on primary care management of human and animal bites.

Search dates

January 2007 – October 2011

Key search terms

Various combinations of searches were carried out. The terms listed below are the core search terms that were used for Medline.

exp Bites/, exp Stings/, bite$.tw.

exp Cat/, cat$.tw., exp Rabbit/, rabbit$.tw., exp Guinea Pig/, (guinea ADJ pig$).tw., exp Mammals/, mammal$.tw.

Table 1 . Key to search terms.
Search commands Explanation
/ indicates a MeSh subject heading with all subheadings selected
.tw indicates a search for a term in the title or abstract
exp indicates that the MeSH subject heading was exploded to include the narrower, more specific terms beneath it in the MeSH tree
$ indicates that the search term was truncated (e.g. wart$ searches for wart and warts)
Sources of guidelines

National Institute for Health and Care Excellence (NICE)

Scottish Intercollegiate Guidelines Network (SIGN)

NICE Evidence

National Guidelines Clearinghouse

New Zealand Guidelines Group

British Columbia Medical Association

Canadian Medical Association

Institute for Clinical Systems Improvement

Guidelines International Network

National Library of Guidelines

National Health and Medical Research Council (Australia)

Alberta Medical Association

University of Michigan Medical School

Michigan Quality Improvement Consortium

Royal College of Nursing

Singapore Ministry of Health

Royal Australian College of General Practitioners

Health Protection Agency

National Resource for Infection Control

CREST

World Health Organization

NHS Scotland National Patient Pathways

Agency for Healthcare Research and Quality

TRIP database

Patient UK Guideline links

UK Ambulance Service Clinical Practice Guidelines

RefHELP NHS Lothian Referral Guidelines

Medline (with guideline filter)

Driver and Vehicle Licensing Agency

Sources of systematic reviews and meta-analyses

The Cochrane Library :

Systematic reviews

Protocols

Database of Abstracts of Reviews of Effects

Medline (with systematic review filter)

EMBASE (with systematic review filter)

Sources of health technology assessments and economic appraisals

NIHR Health Technology Assessment programme

The Cochrane Library :

NHS Economic Evaluations

Health Technology Assessments

Canadian Agency for Drugs and Technologies in Health

International Network of Agencies for Health Technology Assessment

Sources of randomized controlled trials

The Cochrane Library :

Central Register of Controlled Trials

Medline (with randomized controlled trial filter)

EMBASE (with randomized controlled trial filter)

Sources of evidence based reviews and evidence summaries

Bandolier

Drug & Therapeutics Bulletin

MeReC

NPCi

BMJ Clinical Evidence

TRIP database

Central Services Agency COMPASS Therapeutic Notes

Sources of national policy

Department of Health

Health Management Information Consortium (HMIC)

Sources of medicines information

The following sources are used by CKS pharmacists and are not necessarily searched by CKS information specialists for all topics. Some of these resources are not freely available and require subscriptions to access content.

British National Formulary (BNF)

electronic Medicines Compendium (eMC)

European Medicines Agency (EMEA)

LactMed

Medicines and Healthcare products Regulatory Agency (MHRA)

REPROTOX

Scottish Medicines Consortium

Stockley's Drug Interactions

TERIS

TOXBASE

Micromedex

UK Medicines Information

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