Animal Bites

Resident Clinical Pearl (RCP) – November 2017

Renée Amiro, R1 FMEM, Dalhousie University, Saint John, New Brunswick

Reviewed by Dr. David Lewis

Mr. Stark brings in his 8-year-old adopted son, Jon Snow, to the emergency room on Christmas day. Jon had just received a puppy, Ghost, as a Christmas present that morning. Jon, who knows nothing (about raising puppies), was playing too rough with the pup and got a bite on his right hand.

How do we appropriately manage this animal bite in the emergency room?

Management

When a patient presents to the ED with an animal bite, the factors in management that need to be addressed are:

1. How to properly care for the wound
2. Is antibiotic prophylaxis needed?
3. Does the wound require closure with sutures?
4. When does a bite require surgical consultation?
5. When should you worry about tetanus and rabies?

Caring for the wound

Managing an animal bite has much of the same principles of usual good wound care

1. Control hemorrhage
2. Preform a neurovascular assessment
3. Clean the wound meticulously. This is very important in animal and human bites. To reduce the number of bacteria, the wound should be flushed with copious amounts of saline or water

Local anesthetic should be used to reduce pain and facilitate cleaning. The wound should also be inspected for foreign bodies. Bites overlying joints should be put through their entire range of motion (bone, tendon or joint capsule involvement). If you suspect a foreign body but can’t see it, get an x-ray.

Pearl: for puncture wounds (cats are the biggest perpetrators), the same principles of wound care apply except superficially irrigate wounds and do not use high pressure

Is antibiotic prophylaxis needed?

Most bites to not require prophylactic antibiotics. There are some high-risk wounds that do. Those include:

1. Deep puncture wounds (think cats)
2. Associated crush injury
3. Injury in areas overlying venous or lymphatic compromise
4. Primary closure of the wound
5. Wounds on hands, genitals or overlying joints
6. Host factors: immunocompromised, diabetes

Table of prophylactic antibiotic choices. Duration of therapy depends on the antibiotic choice.

Ellis and Ellis. Am Fam Physician. 2014 Aug 15;90(4):239-243.

Does the wound requires closure with sutures

Generally, no, especially if cats are the perpetrators. But if cosmetic concerns arise, wounds should meet all the following criteria before primary closure:

1. Clinically uninfected
2. < 12 hrs old (<24 hrs on the face)
3. NOT located on the hand or the foot

The wound should NOT be closed primarily if the following criteria are met:

1. Crush injuries
2. Hand and foot wounds
3. Deep puncture wounds
4. Cat or human wounds
5. Immunocompromised host
6. >12 hrs old

When does a bite require surgical consultation?

If the injury results in complex facial wounds, neurovascular compromise, osteomyelitis or joint infection or deep wounds that penetrate underlying structures (joint, bone, tendon), get a surgical consultation.

That being said, consider consultation with any deep wound on the hand.

When do I worry about tetanus and rabies prophylaxis?

When considering tetanus prophylaxis, the decision to intervene is the same in non-bite wounds.

   Ellis and Ellis. Am Fam Physician. 2014 Aug 15;90(4):239-243.

For rabies, post-exposure prophylaxis is generally not needed in patients with a dog or cat bite as long as the animal is not showing signs of rabies: dysphagia, abnormal behaviour, paralysis, seizures and ataxia.

Ellis and Ellis. Am Fam Physician. 2014 Aug 15;90(4):239-243.

Bottom Line: Animal bites, like other wounds, require regular wound care with a focus on meticulous cleaning. Cat bites usually need prophylactic antibiotics, dogs usually do not. All immunocompromised hosts get prophylactic antibiotics

References

1. Baddour, L. and Sexton, D. Soft tissue infections due to dog and cat bites. Retrieved from https://www.uptodate.com/contents/soft-tissue-infections-due-to-dog-and-cat-bites. Accessed August 1, 2017.
2. Callaham, M. Controversies in antibiotic choices for bite wounds. Ann Emerg Med 1988; 17:1321.
3. Ellis, R. and Ellis, C. Am Fam Physician. 2014 Aug 15;90(4):239-243.

This post was copyedited by Kavish Chandra @kavishpchandra