Exam 1 - Equine Musculoskeletal/Joint Infections

Question 1

what are the different pathways in which synovial infections can happen?

Answer 1

hematogenous - foals

traumatic/wounds

post injection

Question 2

what are the different pathways in which osteitis/osteomyelitis can happen?

Answer 2

hematogenous

traumatic/wounds

post-fracture fixation

Question 3

what are examples of direct inoculation resulting in synovial infections?

Answer 3

wound associated or iatrogenic from infection/sx

affects joints/tendon sheaths/bursa

Question 4

what are some potential complications of a resolved synovial infection?

Answer 4

lame horse with OA/DJD & support limb issues

Question 5

what happens if you have a synovial infection that is unresolved?

Answer 5

fatal to the horse

Question 6

T/F: an infected synovial structure always results in severe lameness

Answer 6

true

Question 7

T/F: if you have a peri-synovial wound without any lameness, it is unlikely that there is any synovial penetration

Answer 7

true

Question 8

T/F: a neonate with a swollen joint may be because the mare stepped on it & not due to infection

Answer 8

true

Question 9

what is the pathogenesis of synovial infections?

Answer 9

animal is inoculated & there is colonization, inflammation, & degradation by proteases/cytokines/free radicles that occurs (can either be hematogenous or direct inoculation)

Question 10

what are some examples of direct inoculation resulting in a synovial infection?

Answer 10

periarticular cellulitis, post intra-articular injection, & post-op patient

Question 11

infection in the synovium of a joint leads to __________ and/or ___________

Answer 11

synovitis/tenosynovitis

Question 12

what happens if there is bacterial colonization in the epiphysis or physis of a bone?

Answer 12

osteomyelitis

Question 13

what is the common signalment of a horse with a synovial infection?

Answer 13

peri-natal horse that is lame (focal lameness) & has swollen joint(s) - swelling may be effusion, or periarticular cellulitis

INFECTED UNTIL PROVEN OTHERWISE

history/physical exam shows prior sepsis or perisynovial injury that is considered open until proven otherwise

Question 14

how is a synovial infection diagnosed?

Answer 14

physical exam, imaging, & joint fluid cytology

Question 15

what imaging modalities are commonly used for diagnosing synovial infections?

Answer 15

rads

ultrasound - hyperechoic fluid

mri

Question 16

what parameters of synovial fluid analysis are consistent with a synovial infection?

Answer 16

WBC > 30,000/uL

neutrophils > 90% of total cell population

TP > 3 gm/dL

Question 17

what components make up a synovial wash?

Answer 17

fluid analysis for cytology

checking for wound communication

Question 18

when may you use a contrast study for a horse with a suspected synovial infection?

Answer 18

use to evaluate, joints, tendon sheaths, & draining tracts

Question 19

how are synovial infections managed?

Answer 19

eliminate/prevent infections - abx, can be systemic/intra-articular, regional perfusion, choose empirically because cultures take 3-10 days (pick based off of expected pathogens/post-inj-sx/open wounds)

preserve joint function - normalize synovial environment

debride/drain

Question 20

how can you normalize the synovial environment?

Answer 20

synovial lavage or open synovial therapy

Question 21

what provides the cortical blood supply?

Answer 21

periosteal bone - external 1/3

endosteal bone - internal 2/3

Question 22

what location do we commonly see osteitis/sequestration in the distal limb?

Answer 22

mc/mt from avulsion injuries - affects the skin/fascia/periosteum & can be non-repairable with exposed bone/bacterial colonization

Question 23

why do we commonly see osteitis/sequestration in the coffin bone of horses?

Answer 23

sole penetration - can affect distal phalanx, navicular apparatus

key is early recognition

Question 24

what is most important if there is sole penetration affecting the navicular apparatus?

Answer 24

early & acute management

Question 25

what are some clinical signs associated with osteitis/sequestration?

Answer 25

persistent drainage (fistula), recurrent drainage, intermittent healing, & non-healing wounds

Question 26

what are some clinical signs of sole penetration of the coffin bone? how do you diagnose it?

Answer 26

recurrent abscessation

rads - look for osteolysis & sequestrum, minimum of 10-14 days

Question 27

what is the treatment of osteitis/sequestration?

Answer 27

surgical debridement!!!! conservative probably doesn’t work that great

Question 28

when would you be able to see signs of osteitis/sequestration on rads?

Answer 28

minimum of 10-14 days after initial injury - takes time for radiographic changes to appear

Question 29

T/F: a horse with a synovial infection will have focal/intense pain on deep palpation of the affected area

Answer 29

true

Question 30

what are some examples of diseases that can hematogenously spread & cause synovial infections in foals?

Answer 30

infected umbilicus, pneumonia, diarrhea, & septicemia