Septic Arthritis

Question 1

true or false: septic arthritis is usually bacterial

Answer 1

true

Question 2

what should you always check in foals with septic arthritis?

Answer 2

US umbilicus

palpate ALL joints to see which are involved

Question 3

normal synovial fluid:

• appearance
• WBC count
• diff neutrophil count
• TP

Answer 3

normal:

• appearance: clear, pale yellow
• WBC <500 cells/dL
• diff <10% neutrophils
• TP <2 g/dL

Question 4

risk factors for septic arthritis in foals

Answer 4

failure of passive transport
normal = >800
partial failure = 400-800
failure = <400

Question 5

signs associated with P type septic arthritis in foals

Answer 5

periarticular swelling usually WITHOUT joint distension or effusion

Question 6

diagnosing septic arthritis (3)

Answer 6

• microbiology (send in blood culture media)
• gross exam of synovial fluid
• clin path of synovial fluid (cell count, TP, smear)

Question 7

treatment for septic arthritis

Answer 7

-Lavage MOST IMPORTANT: early + often + big volumes (5-10 L) until signs are gone
-arthroscopic is best because can debride but
requires GA
-needle through and through method: not as
targeted but can be done standing. Requires
LARGE needle (14, 16, or 18 G)
-use balanced electrolyte solution (LRS, normosol,
plasmalyte) +/- DMSO
-saline is last resort
-DO NOT use antiseptics (not effective + cytotoxic)
-broad spectrum antibiotics if needed (penicillin, gentamycin)

Question 8

what might you see on US for septic arthritis?

Answer 8

hypercellular joint fluid

***also always check umbilicus for foals

Question 9

G.S. for diagnosing septic arthritis

Answer 9

microbiology (send in blood culture media; good idea to also send for fungal; repeat a second time if first time is negative; ideally culture BEFORE antibiotics/treatment)

staph is most common

Question 10

E type septic arthritis in foals:

• what does it affect?
• age?
• number of joints involved?

Answer 10

• epyphysis/bony involvement (rads show subcondral lysis)
• weeks old
• usually multiple joints involved

Question 11

normal fibrinogen in horses? what level might you see with septic arthritis if bone involved?

Answer 11

normal: <400 mg/dL

if bone involved often >900 mg/dL

Question 12

diagnosis of septic arthritis in foals (5)

Answer 12

-rads
-BW:
-fibrinogen usually >900 mg/dL when bone is
involved (normal is <400)
-+/- leukocytosis
-US: hypercellular fluid
-***always also check umbilicus
-synovial fluid aspirate (aspirate physis if p type):
-cell count >50,000
-neutrophils >90%
-color: normal to cloudy/red/orange/pink
-palpate ALL joints to see which are involved

Question 13

most common organism cultured during septic arthritis cases

Answer 13

staph

Question 14

types of septic arthritis in foals

Answer 14

• S type (affects synovial membrane and fluid)
• E type (epiphysis/bone involved)
• P type (physis involved)

Question 15

complications of septic arthritis

Answer 15

• contralateral limb laminitis
• DJD
• ankylosis
• euthanasia

Question 16

E type septic arthritis in foals:

• signs?
• most commonly affected sites?
• number of joints usually involved?

Answer 16

• signs: rads show subcondral lysis, history of FPT or disease, MILD lameness THEN acute exacerbation of lameness/effusion
• distal femur, talus, tibia, radius
• usually multiple joints involved

Question 17

septic arthritis secondary to trauma is most commonly _____ in origin

Answer 17

enterobacter

also can be staph, pseudomonas, fungal

Question 18

what important things to remember about lavaging septic joints? what two methods can you use?

Answer 18

-Lavage MOST IMPORTANT: early + often + big volumes (5-10 L) until signs are gone
-arthroscopic is best because can debride but
requires GA
-needle through and through method: not as
targeted but can be done standing. Requires
LARGE needle (14, 16, or 18 G)
-use balanced electrolyte solution (LRS, normosol,
plasmalyte) +/- DMSO
-saline is last resort
-DO NOT use antiseptics (not effective + cytotoxic)

Question 19

septic arthritis secondary to arthrocentesis is usually ______ in origin

Answer 19

staph

Question 20

S type septic arthritis:

• most common joints involved?
• number of joints usually involved?
• C.S.?

Answer 20

• signs: acute SEVERE lameness, effusion
• usually multiple joints involved
• common sites: usually larger joints (stifle, tibiotarsal)

Question 21

causes of septic arthritis in horses

Answer 21

• trauma (usually enterobacter; also staph, pseudomonas, fungal)
• hematogenous (usually only foals)
• iatrogenic (usually staph)

Question 22

P type septic arthritis in foals:

• age?
• common sites?
• number of sites common?

Answer 22

• age: older (weeks to months)
• number of sites: usually one physis
• common sites: distal physis of MCIII/MTIII, radius, tibia

Question 23

difference in presentation between S type and E type of septic arthritis in foals

Answer 23

S type: SEVERE lameness; usually no bone involvement; just synovial membrane and fluid; usually <1 week

E type: bone involved, usually MILD lameness THEN acute exacerbation of lameness/effusion; usually weeks old with history of FPT or disease

both usually involve multiple joints

Question 24

what size needle do you need to lavage septic joints using needle through and through method?

Answer 24

14, 16, or 18 G

Question 25

S type septic arthritis in foals:

• what does it affect?
• age?
• number of joints involved?

Answer 25

• affects synovial membrane and fluid;
• usually < 1 week old
• usually multiple joints involved

Question 26

true or false: you should NEVER debride a physis

Answer 26

TRUE

Question 27

abnormal synovial fluid parameters:

• appearance
• WBC count
• diff neutrophil count
• TP

Answer 27

• turbid, serosanguinous
• WBC: thousands +
• > 90% neutrophils
• > 3.5 g/dL