Tetanus Prophylaxis for Dog Scratches
Yes, administer a tetanus toxoid-containing vaccine (Tdap preferred) for dog scratches if ≥5 years have elapsed since the last dose, as dog scratches are classified as contaminated, tetanus-prone wounds. 1
Wound Classification
Dog scratches are classified as contaminated, tetanus-prone wounds because they may be contaminated with dirt, soil, saliva, and debris that harbor Clostridium tetani spores. 1 This classification is critical because it determines a 5-year interval (not 10-year) for booster administration, rather than the routine 10-year interval used for clean, minor wounds. 1
Vaccination Algorithm Based on Immunization History
For Patients with ≥3 Previous Doses:
If last dose was <5 years ago: No tetanus toxoid-containing vaccine or TIG is needed. 1
If last dose was ≥5 years ago: Administer tetanus toxoid-containing vaccine WITHOUT TIG. 1 Tdap is strongly preferred over Td for persons aged ≥11 years who have not previously received Tdap or whose Tdap history is unknown, as this provides additional protection against pertussis. 1, 2
For non-pregnant persons with documented previous Tdap vaccination, either Td or Tdap may be used. 2
For Patients with <3 Previous Doses or Unknown History:
Administer BOTH tetanus toxoid-containing vaccine (Tdap preferred) AND TIG 250 units IM at separate anatomical sites using separate syringes. 1, 2 These patients must complete a 3-dose primary tetanus vaccination series for long-term protection. 1
Patients with unknown or uncertain vaccination histories should be considered to have had no previous tetanus toxoid doses. 2
Special Populations
Pregnant women: Use Tdap regardless of prior Tdap history if tetanus prophylaxis is indicated. 2, 3
Severely immunocompromised patients (HIV infection, severe immunodeficiency): Receive TIG regardless of tetanus immunization history when contaminated wounds are present. 1, 2
Patients with history of Arthus reaction: Should not receive tetanus toxoid-containing vaccine until >10 years after the most recent dose, even with contaminated wounds. 1
Critical Clinical Pearls
Do not confuse the 10-year routine booster interval with the 5-year interval for contaminated wounds—this is the most common error in tetanus prophylaxis. 1 The 10-year interval only applies to clean, minor wounds, not dog scratches. 1
Thorough wound cleaning and debridement are essential first steps to remove debris that might harbor Clostridium tetani spores. 3 However, wound care alone is insufficient—appropriate vaccination based on immunization history is required. 3
More frequent doses than recommended may be associated with increased incidence and severity of adverse reactions, including Arthus-type hypersensitivity reactions. 1 Do not administer tetanus boosters more frequently than the evidence-based intervals. 1
Tetanus toxoid provides protection against the next injury, not the current injury, as antibody response takes time to develop. 4 However, persons who have received at least two doses of tetanus toxoid rapidly develop antitoxin antibodies after a booster dose. 1
Common Pitfalls to Avoid
Do not assume dog scratches are "clean wounds"—they must be treated as contaminated, tetanus-prone wounds requiring the 5-year interval for booster consideration. 3
Do not delay wound care while waiting for vaccination records—if history is uncertain, treat as unvaccinated and administer both vaccine and TIG. 3
Verify vaccination history carefully—clinical decision support systems have demonstrated that up to 22% of patients receive potentially unnecessary tetanus vaccines when prior vaccination within 10 years is not recognized. 5