Can a cat bite cause cellulitis?

Cat Bites Commonly Cause Cellulitis

Yes, cat bites frequently cause cellulitis, with 30-50% of cat bite wounds becoming infected, making them among the highest risk animal bites for developing infection. 1

Pathophysiology and Risk Factors

Cat bites pose a particularly high risk of infection due to several factors:

• Cat teeth are sharp and narrow, creating deep puncture wounds that:

  • Introduce bacteria deep into tissues
  • Create small surface openings that seal quickly, trapping bacteria inside
  • Are difficult to clean effectively

• The oral flora of cats contains numerous pathogens:

  • Pasteurella multocida (found in 75% of cat bite infections) 1
  • Staphylococcus species (including MRSA)
  • Streptococcus species
  • Anaerobic bacteria (present in 65% of cat bite infections) 1
  • Capnocytophaga species

• Bite location significantly impacts infection risk:

  • Bites over joints or bones
  • Hand and wrist bites (particularly dangerous due to proximity to tendons, joints, and limited soft tissue)

Clinical Presentation

Cellulitis from cat bites typically develops rapidly, often within 12-24 hours after injury 2, and presents with:

• Erythema (redness)
• Swelling
• Pain disproportionate to the visible wound
• Warmth
• Serosanguineous or purulent drainage
• Lymphangitis (red streaking)
• Systemic symptoms in severe cases (fever, chills)

Management Approach

1. Wound Care:

   • Thorough irrigation with sterile normal saline 1
   • Removal of superficial debris
   • Deep irrigation to remove foreign bodies and pathogens
   • Avoid high-pressure irrigation which may spread bacteria deeper 1

2. Antibiotic Therapy:

   • For all cat bites with signs of infection
   • For fresh, deep wounds even without infection
   • For bites in high-risk locations (hands, feet, face, genitals, near joints)
   • For immunocompromised patients

3. Antibiotic Selection:

   • First-line oral therapy: Amoxicillin-clavulanate (covers both Pasteurella and anaerobes) 1

   • Alternative oral options:

     • Doxycycline
     • Combination of penicillin VK plus dicloxacillin

   • Intravenous options (for severe infections):

     • β-lactam/β-lactamase combinations (ampicillin-sulbactam)
     • Piperacillin-tazobactam
     • Second-generation cephalosporins (cefoxitin)
     • Carbapenems (ertapenem, imipenem, meropenem)

   • Avoid these antibiotics due to poor activity against Pasteurella multocida:

     • First-generation cephalosporins (cephalexin)
     • Penicillinase-resistant penicillins (dicloxacillin)
     • Macrolides (erythromycin)
     • Clindamycin alone 1

4. Duration of Therapy:

   • Simple cellulitis: 5-7 days
   • Complicated infections: 10-14 days
   • Bone/joint involvement: 3-6 weeks

Complications to Monitor For

• Septic arthritis
• Osteomyelitis
• Tenosynovitis
• Abscess formation
• Bacteremia (particularly concerning in asplenic or immunocompromised patients)
• Sepsis (can be caused by Capnocytophaga canimorsus or Pasteurella multocida) 3

Special Considerations

• Pain disproportionate to visible injury near a bone or joint suggests periosteal penetration 1
• Cat bites to the hand carry particularly high risk of complications and often require more aggressive management
• Consider tetanus prophylaxis if indicated
• Evaluate need for rabies prophylaxis in cases involving feral or unknown cats

Common Pitfalls

1. Underestimating cat bites: Despite their small appearance, cat bite wounds have higher infection rates than dog bites
2. Delayed treatment: Infections can progress rapidly within 12-24 hours
3. Inadequate antibiotic coverage: Failing to cover Pasteurella multocida
4. Insufficient follow-up: Patients should be monitored closely for developing complications
5. Missing deep structure involvement: Always evaluate for tendon, joint, or bone involvement, especially with hand wounds