Animal Bites – Mammalian

Bite Me by Mr Dtb

Dog, and other mammalian bites, are a common presentation with the ED.

They can be easy to treat, but need some particular attention if we are going to get them right.

It has been estimated that dog bites account for 60-90% of bites, cat bites for 5-20% and human bites for 4-23%.
Cat bites are around twice as likely as dog bites to become infected because of the deep inoculation of bacteria into the puncture wounds caused by their small, sharp teeth.
Bites to the hand are particularly prone to infection.
Human bites are known to be at risk of infection with clenched fist injuries (“fight bite”) especially so.
Patients may not report human bites spontaneously – based on audit of 96 patients presenting to an emergency department with skin injuries caused by human bites 38 did not report cause until additional history was elicited – Emerg Med J 2005 Dec;22(12):88

History

Should be careful and focus on determining extent of damage and likelihood of infection

Type of animal – approximate breed or size is particularly important in dog bites.
Duration since injury.
Whether provoked or unprovoked.
Care needs to be taken to assess the risk of rabies, [esp. bats in UK] and treat appropriately.
General medical history of patient including tetanus status. With a particular attention to any immunocompromising factors.
For Human Bites, who was bitten and by whom, and any relevant medical history of the donor (biter). (See also sex-bites-and-needle-sticks)

If an animal has bitten a child

Consider the possibility of poor parenting and supervision. This may require referral for safeguarding or discussion with the consultant on duty if concerns of immediate risk. (Dog Bites- Do you need to inform police? – HERE)

Physical examination

should follow the normal pattern for an injury of that site – for example joint function, neurovascular function – but should include..

The presence of any foreign bodies (for example teeth) in the wound.
The size, extent, and depth of the injury.
The type of wound (for example laceration, puncture, abrasion, crush).
The degree of crush injury, devitalised tissue, nerve or tendon damage, and involvement of muscle, bones, joints, or blood vessels.
Any signs of infection.
Any lymphadenopathy
Any possibility of underlying fracture, or foreign bodies (for example teeth) in the wound – it is wise to gain x-ray if there is any doubt.

Treatment

Mammalian bites should focus on the management of risk of infection

If possible remove any foreign bodies.
Copious irrigation with normal saline.
Wide bore IV cannular can be used to assist in access to small puncture wounds and etc. but care needs to be given not to use high pressure irrigation as this can force bacteria into deeper tissues.
Consider iodine bath.
Debride devitalised tissue.

Primary Closure

Is controversial, but in uncomplicated wounds with no risk factors for infection that have been adequately assessed, cleaned and debrided this may be considered.

Allow the following bite wounds to heal without formal closure:
- Bite wounds over 24 hours old.
- Infected bite wounds.
- Deep puncture wounds (for example cat bites).
- Crush injuries.
- Heavy contamination.
- Uncertain adequacy of debridement.
- Bites to the limbs, hands and feet.

Facial bites

Should be closed for cosmetic effect. However, strongly consider referral specialist service (MaxFax locally) in this case.

BMC Emerg Med 2013;13 Suppl 1:S2

Prescribe prophylactic oral antibiotics for:

All cat bites;
bites to the hand, foot, and face and genitalia;
puncture (or any wound that breaches the dermis), or crush wounds;
wounds requiring surgical debridement;
wounds involving bones, joints, tendons, ligaments, or suspected fractures;
bites on limbs with impaired circulation.
Wounds that have undergone primary closure.
People who are at risk of serious wound infection (for example those who are diabetic, cirrhotic, asplenic, immunocompromised, or at extremes of age).
People with a prosthetic valve or joint.
Delayed presentation (more than 8 hours but less than 24–48 hours)
All human bite wounds under 72 hours old
Prescribing guidance

BAT BITES

Some bats in Europe carry a rabies virus called European Bat Lyssavirus (EBLV). This is not classical rabies, but can be fatal none the less.

The risk of exposure is very low. Passive surveillance of bats for rabies in the UK since 1986 has found it in only 14 bats, of over 15,000 tested.
We have 17 breeding species in the UK; EBLV2 virus has never been found in any other bat species in the UK than Daubenton’s bat.
Bats are not normally aggressive and will avoid contact with humans. So there is little risk unless handling bats (occupational or on occasion a member of the public finding an injured bat)

Bat Conservation Trust

Rabies can be prevented by vaccine administered before virus exposure (preexposure prophylaxis) or administered after exposure but before onset of clinical symptoms (postexposure prophylaxis)
after symptom onset, infection is nearly always fatal.

OTHER MAMMALIAN BITES

Though less common there is varying risk of bacterial infection from other mammalian bites. In the event of significant tissue damage, open fracture or other complex bites advice should be sought on appropriate prophylaxis, initially from the consultant on duty, but it may be necessary to discuss with the microbiologist on call.

Specific risk include

Cat scratch disease (not limited to cats)
Rat bite fever (any rodent bite)
Dangerous Dog – child safeguarding