Wise Use of Antibiotics: Management Strategies for Common Animal Bites

Column Author: Marsha A. Dannenberg, MD | Clinical Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

Joshua Herigon, MD, MPH, MBI | Medical Director, Antimicrobial Stewardship Program, Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Education Assistant Professor of Pediatrics, University of Kansas School of Medicine

Column Editor: Rana El Feghaly, MD, MSCI | Associate Chair, Ambulatory & Regional Quality Improvement, Department of Pediatrics; Director, Outpatient Antimicrobial Stewardship Program; Director, Infectious Diseases Clinical Services; Medical Director, Vaccines for Children (VFC) Program, Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

Animal bites, whether from a playful pet or a wild encounter, are a common occurrence for which patients seek medical care. They can range from minor abrasions to serious medical emergencies. An estimated 5 million human or animal bite wounds occur annually in the United States¹ and account for a significant number of emergency department visits each year.

Treatment considerations include:

• Prophylactic antibiotics – are they indicated? And if so, which antibiotic, at what dose, and for how long?
• Is rabies prophylaxis indicated?
• Does tetanus vaccine need to be administered?

Not all bites are equal, and treatment recommendations vary depending on the type of animal, mechanism of injury, and location and severity of the bite.

Risk of infection: When are prophylactic antibiotics needed?

The most important initial step to help prevent infection is thorough cleansing of the wound and irrigation with tap water, followed by debridement or removal of any foreign material if necessary. Avoid high-pressure irrigation as this can drive infectious agents deeper into the tissue.

This cleansing is usually sufficient for mild injuries that only abrade the skin.

Post-exposure prophylactic antibiotics are indicated for the following:

• Moderate to severe injuries such as crush injuries or puncture wounds, especially wounds that penetrate bone, tendon sheath or joint capsule.
• Deep or sutured facial wounds.
• Wounds of the hands, feet or genitalia.
• Immunocompromised patients, including those with asplenia or liver disease.
• All cat bites: The rate of infection after a bite varies depending on the animal, but because cat bites are often deeper puncture wounds, infection rates can be as high as 50%; thus, prophylactic antibiotics are recommended.¹

Which antibiotic is best?

When prophylactic antibiotics are indicated, amoxicillin-clavulanate is the treatment of choice for most bite wounds as it provides coverage for skin flora (Streptococci and methicillin-susceptible Staphylococcus aureus) and oral flora (e.g., Haemophilus spp.), as well as bacteria found in the saliva of dogs and cats (e.g., Pasteurella spp.) and humans (e.g., Eikenella).¹

• Dosing for amoxicillin-clavulanate is 22.5 mg/kg/dose twice daily, using a 7:1 or 4:1 ratio product (using formulations with lower clavulanate concentration, such as ES or XR, would result in underdosing of clavulanate).
• Prophylaxis duration is three days to prevent infection.
• A longer duration of five to seven days is required for treatment of an infected bite wound.
• If the patient has a true allergy to amoxicillin, then two antibiotics should be used, typically clindamycin and either doxycycline or trimethoprim/sulfamethoxazole.²

Rabies prophylaxis

Post-exposure rabies prophylaxis should be administered for any bites from bats, raccoons, skunks, foxes, mongooses, most other carnivores and groundhogs, if the animal cannot be recovered to evaluate for rabies.

Post-exposure rabies prophylaxis includes:

• Rabies immune globulin (RIG): 20 IU/kg on day 0. As much of the RIG dose as possible should be used to infiltrate the wound if present. Any remaining volume should be administered intramuscularly at an anatomical site distant from rabies vaccine administration.
• Human rabies vaccine (1 mL IM) on days 0, 3, 7 and 14.

Bites from healthy domestic pets such as dogs, cats and ferrets carry a much lower risk. If the animal can be observed for 10 days, post-exposure prophylaxis can be delayed but should be initiated immediately if the animal begins to show any signs of rabies.

Post-exposure prophylaxis should also be initiated immediately if there are severe bites to the head, neck or trunk after an unprovoked attack (i.e., injured person was not attempting to interact with the animal prior to the bite) or the observation period cannot be completed.

Bites from livestock, rodents and lagomorphs (rabbits, hares and pikas) typically do not require post-exposure prophylaxis.³

Tetanus vaccination

Remember to review tetanus vaccine status in all patients with animal bites.

• If the vaccine status is unknown or the patient has received fewer than three tetanus-containing vaccines, administer tetanus toxoid vaccine and tetanus immune globulin.
• If the patient has received three or more tetanus vaccines but the last vaccine was over five years ago, administer tetanus toxoid vaccine only.
• Regardless of wound type, no tetanus toxoid vaccine is necessary if the patient has completed the primary tetanus vaccine series, and the last tetanus vaccine was less than five years ago.⁴

Conclusion

Animal bites are common and their treatment addresses both immediate and long-term risks. From thorough wound cleansing to the administration of tetanus vaccines, rabies prophylaxis, or antibiotics when necessary, proper treatment is essential in preventing complications like infection or disease transmission.

The Children’s Mercy Department of Evidence Based Practice has recently reviewed the most current literature and created a new Animal Bite (Mammal) Clinical Pathway to ensure standardized care and high-quality treatment across diverse health care settings.

For more information

Animal Bite (Mammal) Clinical Pathway: https://www.childrensmercy.org/siteassets/media-documents-for-depts-section/documents-for-health-care-providers/block-clinical-practice-guidelines/mobileview/animal-bites-algorithm.pdf

References:

1. Committee on Infectious Diseases, American Academy of Pediatrics. Bite wounds. In: Kimberlin DW, Banerjee R, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2024-2027. Report of the Committee on Infectious Diseases. 33rd ed. American Academy of Pediatrics; 2024: 202-206.
2. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft-tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-e52. doi:10.1093/cid/ciu444
3. Committee on Infectious Diseases, American Academy of Pediatrics. Rabies. In: Kimberlin DW, Banerjee R, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2024-2027. Report of the Committee on Infectious Diseases. 33rd ed. American Academy of Pediatrics; 2024: 702-711.
4. Tiwari TSP, Moro PL, Acosta AM. Tetanus. In: Hall E, Wodi AP, Hamborsky J, Morelli V, Schillie S, eds. Centers for Disease Control and Prevention Pink Book: Epidemiology and Prevention of Vaccine-Preventable Diseases. 14th ed. Public Health Foundation; 2021: 315-328.