Page 1360 - Cote clinical veterinary advisor dogs and cats 4th

Necrotizing Fasciitis 685

RISK FACTORS DIAGNOSIS ○ Negative-pressure wound therapy has
Injury, such as a bite wound or motor vehicle Diagnostic Overview been used successfully as an additional
VetBooks.ir CONTAGION AND ZOONOSIS A presumptive diagnosis is made when soft- • IV antibiotics: beta-lactamase–resistant Diseases and Disorders
management tool.
accident
tissue pain is disproportionate to evident trauma
antibiotics are generally effective against S.
The risk of zoonosis is low, but humans can have
therapy may be superior due to the risk of
On palpation and probing of the affected area,
the same clinical disease caused by the same/ and subcutaneous tissues can be easily dissected. canis; initially broad-spectrum antimicrobial
similar organisms. Considering the potential a lack of resistance of affected fascial planes polymicrobial infections.
severity of disease, good hygiene practices is characteristic. Fractures as a source of pain ○ Clindamycin 11 mg/kg IV q 12h;
should be employed, especially in cases of are ruled out with radiographs. Confirmation clindamycin is considered a drug of choice
broken skin or mucous membrane contact. requires bacterial culture and histopathology, for human necrotizing fasciitis, or
Risk may be increased for immunocompromised but treatment must be instituted before results ○ Cefoxitin 30 mg/kg IV q 6h, or
individuals. of these tests are available. ○ Cefazolin or ampicillin/sulbactam 22 mg/
kg IV q 6h plus enrofloxacin 20 mg/kg
ASSOCIATED DISORDERS Differential Diagnosis IV q 24h (dogs) or 5 mg/kg q 24h (cats);
Toxic shock syndrome • Cellulitis alternatively, cefazolin or ampicillin/
• Subcutaneous abscess, seroma, or hematoma sulbactam as above plus amikacin 20 mg/
Clinical Presentation • Soft-tissue or orthopedic trauma kg IV q 24h (dogs and cats)
DISEASE FORMS/SUBTYPES ○ Fractures ○ Enrofloxacin may be associated with
Type II (single-organism) infections of beta- ○ Blunt trauma increased risk of streptococcal toxic shock
hemolytic group G Streptococcus predominate ○ Bites syndrome and should be used with caution
in dogs, but other causative agents have been ○ Penetrating projectiles (e.g., gunshot) when Streptococcus species are suspected
identified. • Envenomation, especially snake bite in necrotizing fasciitis.
• Hyperbaric oxygen therapy and pentoxofyl-
HISTORY, CHIEF COMPLAINT Initial Database line (15-30 mg/kg PO q8-12h) may improve
Many patients have a history of penetrating • CBC, serum biochemistry profile, urinalysis outcome and assist with wound management.
trauma, but cases have also been reported ○ Nonspecific abnormalities consistent with • Aggressive analgesia, titrated to need
after vaccination and nonpenetrating wounds. severe inflammation (e.g., neutrophilic ○ Opioids (e.g., morphine sulfate 0.05-
Swelling and lameness may be noted by leukocytosis with left shift) 0.15 mg/kg/h IV constant rate infusion
owner. • Radiographs of affected areas to rule out or buprenorphine 0.02 mg/kg IV q 6h)
• Concurrent sepsis results in typical clinical fractures and other lesions as causes of pain combined with a nonsteroidal antiinflam-
signs: anorexia, depression, lethargy, and • Advanced or septic cases have abnormalities matory drug (NSAID) such as carprofen
weakness, leading to hypotension, shock, consistent with sepsis and/or disseminated 2.2 mg/kg SQ or PO q 12h unless
and multiorgan failure (p. 907) intravascular coagulation (DIC [p. 269]). contraindicated
• Clinical disease is acute and rapidly ○ Previous concerns that NSAIDs caused
progressive Advanced or Confirmatory Testing poorer outcomes in humans was not sub-
Cytology of fluids or affected tissues may reveal stantiated in prospective and retrospective
PHYSICAL EXAM FINDINGS exudate with cocci in pairs or chains in cases studies.
• Signs include localized heat, swelling, with Streptococcus, increasing clinical suspicion
erythema, and pain (severe). for the disease. Diagnostic confirmation is made Chronic Treatment
○ Muscle bellies may be hard and severely by histopathology and culture of the causative Chronic wound management may be needed.
painful on palpation. organism, but treatment must be instituted
• Skin is variously affected, ranging from before these results are available. Nutrition/Diet
normal to soft and exudative to an Enteral feeding is preferred over parenteral
erythematous/blackened eschar TREATMENT unless contraindicated. Feed twice the basal
• Limb involvement is commonly reported in requirements.
dogs. Treatment Overview
• Systemic signs include fever, tachycardia, and Immediate, aggressive treatment consists of wide Drug Interactions
dehydration. surgical excision of affected tissue, appropriate NSAIDs: avoid in septic shock or dehydrated
antimicrobial therapy, intensive pain manage- animals
Etiology and Pathophysiology ment, and medical therapy for shock and sepsis
• Causative organism: Lancefield group G, if present. Possible Complications
beta-hemolytic Streptococcus consistent; Strep- Delaying treatment waiting for diagnos-
tococcus canis is most commonly cultured. Acute General Treatment tic results or not treating aggressively
Staphylococcus pseudintermedius, Clostridium • Immediate aggressive treatment for SIRS and enough increases risk of sepsis, SIRS, and
spp, Pasteurella multocida, Pseudomonas septic shock, if present (p. 907) death.
aeruginosa, and other bacteria have been • Early, aggressive surgical debridement
reported to cause necrotizing fasciitis. ○ Immediate owner consent for amputation Recommended Monitoring
• Bacterial exotoxins and proteases cause for limb infections; guarded prognosis and • Monitor patients for septic shock, DIC, and
tissue destruction/necrosis and clinical risk of reoperation should be discussed infection progression that would warrant
signs. ○ Debridement of all necrotic and further debridement.
• An extremely rapid course of progres- questionable tissue and drainage (often • Monitor bandages for amount and character
sion (line of tissue inflammation/edema by fasciotomy) are indicated; copious of exudate.
visibly advances over minutes to hours) surgical lavage with warm isotonic fluids
is a hallmark of necrotizing fasciitis, ± chlorhexidine 0.05% PROGNOSIS & OUTCOME
ultimately leading to sepsis and/or the ○ Wet-to-dry bandaging until infection is
systemic inflammatory response syndrome controlled; the bandage should contain a Surgical delay, incomplete debridement, and
(SIRS). thick absorptive layer. concurrent sepsis are negative prognostic factors.

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