What is the recommended dose of immunoglobulin (IG) for post-exposure prophylaxis in a dog bite?

Rabies Immunoglobulin Dosing for Dog Bites

The recommended dose of rabies immunoglobulin (RIG) for post-exposure prophylaxis following a dog bite is 20 IU/kg body weight, administered once at the initiation of treatment. 1, 2, 3

Dosing Specifications

• The 20 IU/kg formula is universally applicable to all age groups, including children and adults. 1, 2
• This dose applies to both human rabies immunoglobulin (HRIG) and equine rabies immunoglobulin (ERIG). 2
• RIG is administered only once—at the beginning of post-exposure prophylaxis—to provide immediate passive immunity while the patient develops an active antibody response to the vaccine. 1, 2

Critical Timing Considerations

• If RIG was not given when vaccination was initiated, it can still be administered through day 7 after the first vaccine dose. 1, 2
• Beyond day 7, RIG is NOT indicated because an antibody response to the cell culture vaccine is presumed to have occurred. 1, 2

Administration Technique

The technique for RIG administration is crucial for efficacy:

• If anatomically feasible, the full calculated dose should be thoroughly infiltrated in the area around and into the wound(s). 1, 2, 3
• Any remaining volume after wound infiltration should be injected intramuscularly at a site distant from the vaccine administration site. 1, 2
• This infiltration recommendation is based on reports of rare post-exposure prophylaxis failures when smaller amounts of RIG were infiltrated at exposure sites. 1, 2

Critical Safety Precautions

• RIG must NEVER be administered in the same syringe or at the same anatomical site as the rabies vaccine. 1, 2
• Do not exceed the recommended 20 IU/kg dose because RIG can partially suppress active antibody production. 1, 2

When RIG is NOT Required

Previously vaccinated persons who received a complete pre-exposure or post-exposure rabies vaccination series do NOT require RIG—only vaccine doses. 1, 2, 3

For these individuals:

• Administer only 2 doses of rabies vaccine (on days 0 and 3). 3
• RIG should not be given as it is unnecessary and may interfere with the anamnestic response. 2, 3

Accompanying Vaccine Schedule

For previously unvaccinated persons receiving RIG:

• Current recommendation is a 4-dose vaccine schedule (days 0,3,7, and 14) along with RIG on day 0. 2
• The older 5-dose schedule (days 0,3,7,14, and 28) is still recommended for immunocompromised patients. 2, 3
• Vaccine should be administered intramuscularly in the deltoid area for adults and older children, or the anterolateral thigh for infants and small children. 1, 3
• Never administer vaccine in the gluteal area as this results in lower neutralizing antibody titers. 1, 3

Essential Wound Management

• Immediate and thorough washing of all bite wounds with soap and water for approximately 15 minutes is critical and has been shown to markedly reduce rabies risk. 1, 3, 4
• Apply a virucidal agent (such as iodine-containing preparation) to the wound if available. 3
• Address tetanus prophylaxis and bacterial infection control as indicated. 1, 3, 4

Common Pitfalls to Avoid

1. Failing to infiltrate the full RIG dose into and around the wound—this is associated with prophylaxis failures. 1, 2
2. Administering RIG and vaccine at the same site—this can interfere with vaccine immunogenicity. 1, 2
3. Using the gluteal area for vaccine administration—this produces inadequate antibody response. 1
4. Giving RIG to previously vaccinated individuals—this is unnecessary and may blunt the anamnestic response. 2, 3
5. Delaying treatment—prophylaxis should begin as soon as possible after exposure, ideally within 24 hours. 1, 4