Should a tetanus (Td) vaccination be updated after a dog bite if the last shot was received 6 years ago?

Tetanus Vaccination After Dog Bite (6 Years Since Last Dose)

Yes, tetanus vaccination should be administered immediately—a dog bite is classified as a contaminated wound requiring a booster if more than 5 years have elapsed since the last dose. 1, 2

Wound Classification

• Dog bites are classified as "non-clean" or "tetanus-prone" wounds because they may be contaminated with dirt, saliva, feces, or other materials 2
• Although dogs and cats are coprophagic and could potentially transmit tetanus, the classification as a contaminated wound drives the prophylaxis decision rather than the specific animal involved 1
• The 5-year interval (not the routine 10-year interval) applies to all contaminated wounds, including animal bites 1, 2

Specific Recommendation for This Case

Since the last tetanus vaccination was 6 years ago (>5 years), administer a tetanus toxoid-containing vaccine immediately without tetanus immune globulin (TIG). 1, 2

Vaccine Selection Algorithm

• If the patient has never received Tdap or Tdap history is unknown: Administer Tdap (preferred over Td alone) 1, 2
• If the patient has documented previous Tdap vaccination: Either Td or Tdap may be used 2
• If the patient is pregnant: Administer Tdap regardless of prior Tdap history 2

TIG Is NOT Required

• TIG (250 units IM) is only indicated for patients with unknown or incomplete vaccination history (<3 doses in primary series) 2, 3
• Since this patient received vaccination 6 years ago, they presumably completed the primary series and only require the booster vaccine 1, 3

Critical Clinical Pearls

The most common error in tetanus prophylaxis is confusing the 10-year routine booster interval with the 5-year interval for contaminated wounds. 4

• For clean, minor wounds: Booster needed only if ≥10 years since last dose 1, 4
• For contaminated/tetanus-prone wounds (including dog bites): Booster needed if ≥5 years since last dose 1, 2, 4
• More frequent dosing than recommended may increase adverse reactions, including Arthus-type hypersensitivity reactions 3

Administration Details

• Administer 0.5 mL intramuscularly in the deltoid muscle 3
• There is no urgency for same-day administration in the acute setting, as the vaccine provides protection against future injuries rather than the current one 5
• However, administration during the initial wound care visit ensures compliance and follows guideline recommendations 1

Special Considerations

• History of Arthus reaction: Defer vaccination until >10 years after the most recent dose, regardless of wound type 1, 2
• Immunocompromised patients (including HIV): Should receive TIG regardless of tetanus immunization history when presenting with contaminated wounds 2, 4
• Guillain-Barré syndrome <6 weeks after previous tetanus vaccine: Carefully weigh risks and benefits before administering 1

Wound Management

• Copious irrigation, cautious debridement, and preemptive antibiotics (amoxicillin-clavulanate preferred) are essential components of dog bite management 1
• Primary wound closure is generally not recommended for dog bites except facial wounds 1

Real-World Evidence

• Case reports demonstrate that tetanus can occur even in previously immunized patients when appropriate post-exposure prophylaxis is not administered 6, 7
• A California study found that 56% of tetanus patients with acute injuries sought medical care, but only 22% received appropriate prophylaxis—highlighting the importance of correct guideline application 7
• One case report documented generalized tetanus in a 79-year-old woman whose last booster was 7 years prior to injury; she did not receive prophylaxis at initial presentation and subsequently developed severe disease 6