Septic arthritis Flashcards
Common cause of infection
- Perforating injury
- Intra-articular injection
- post-operative infection of joint/tissues
Common etiology traumatic infections
enteric bacteria
Common etiology of iatrogenic infections
Staphylococcus aureus
Septic arthritis
- Acute
- purulent exudate
- rapid destruction articular cartilage
- lysosomal enzymes released by neutraphils
Modes of joint infections
- Primary: direct penetration
- Secondary: extension of infection from adjacent tissues into joint
- Tertiary: Hematogenous from other infected area
Young animals
- 1 or more joints involved
- usually hematogenous
Older animal
- Usually only 1 joint
- Usually from direct penetration or extension from adjacent infection
Clinical signs
- Extreme pain, ush not weightbearing
- Heat and swelling around infected joint
- Fluid distention and edema
- Foals may present with septicemia
- Septic arthritis may be discovered during foal exam
- Animal may be depressed, off feed, sweating, febrile
Classification of hematogenous septic arthritis/osteomyelitis in foals
S type: synovial
E type: epiphyseal - worst prognosis
P type: physeal
S type infection
- Confined to joint space
- No evidence of osteomyelitis
E type
- Infection begins in subchondral bone of epiphysis
- May extend through articular cartilage into joint
- Worst prognosis because of collapse of unsupported articular cartilage
P type
Infection begins near physis
-from metaphyseal side
Radiographic signs
- Early-soft tissue swelling, increase in joint space if limb weighbearing
- Late-narrowing of joint space, lysis subchondral bone, periosteal proliferation
Diagnosis
- PE
- CBC/CHem
- adult horses: hyperfibrinogenemia, +/- high/normal WBC
- Foal: moderate leukocytosis, neutrophilia, hyperfibrinogenemia, blood culture
Clin path joint fluid
- yellow/grey/blood tinged/cloudy/fibrin/pus
- 20,000-200,000 leukocytes/mm3; > 90% neuts
- Low pH (normal is 7.3)
Culture of joint
- Negative culture doesn’t rule out infection
2. Cetrifugation and culture of sediment
Differentiate septic arthritis from
fractures
osteomyelitis
Diagnosis septic arthritis is by
arthrocentesis
-don’t delay if you suspect septic joint
Joint ill in foals check for
- Diarrhea
- Umbilical infection
- Pneumonia
- Systemic illness
- Infection in other joints
Common enterobacteriacea
- E. Coli
- Enterobacter sp
- Klebsiella sp
- Proteus sp
- Providencia sp
- Salmonella sp
Other common etiology
- Actinobacillus equuli
- Streptococcus sp
- Rhodococcus equi
Treatment
- Joint lavage isotonic fluids-then instill abx in joint
- IV regional limb perfusion
- broad spectrum antibiotics
- penicillin + aminoglycoside (gent)
- rifampin + clarithromycin
- enrofloxacin - supportive bandages and cold therapy
- NSAIDS
- IV sodium hyaluronate or IM adequan during recup
Regional limb perfusion
Use 1/3 the systemic dose
Tourniquet for 30 minutes
Can do intraosseous
DMSO joint lavage
- 10-40% solutions
- Oxygen-derived free radical scavenger
- antibiotic properties
- not approved for this use
Other pain management
- Epidural alpha 2s
2. fentanyl patch
