Exam 2 - Rhodococcus Equi, Foal Pneumonia

Question 1

what is the leading cause of disease & death in foals in texas > 1 month old?

Answer 1

pneumonia

Question 2

what agent is the most common cause of severe pneumonia in post-neonatal, older than 1 week old, foals?

Answer 2

rhodococcus equi

Question 3

in the united states, what is the 3rd leading cause of disease & 2nd leading cause of death in foals?

Answer 3

pneumonia

Question 4

why does r. equi have a significant economic impact at endemic farms?

Answer 4

high incidence, high case fatality rates, labor/expense of diagnostic screening, prolonged, & expensive treatment

Question 5

what is the etiology of rhodococcus equi?

Answer 5

pleomorphic, gram positive coccobacillus

Question 6

what are the routes of infection for r. equi?

Answer 6

inhalation & ingestion

Question 7

what is the pathogenesis of r. equi?

Answer 7

bacteria survive & replicate within alveolar macrophages - inhibits phagosome-lysosome fusion

Question 8

T/F: r. equi infections in humans is becoming increasingly recognized in human patients

Answer 8

true

Question 9

what are the clinical syndromes of r. equi? what is the most common?

Answer 9

1. subclinical infection
2. chronic, progressive, infection
3. acute on chronic
4. peracute onset of respiratory distress
5. sudden death

subclinical infection

Question 10

when are foals most commonly affected by r. equi?

Answer 10

most are exposed early in life & become infected shortly after

clinical signs between 3-16 weeks of age

Question 11

T/F: r. equi is rare in adult horses & foals older than 6 months

Answer 11

true

Question 12

what kind of pneumonia does r. equi cause?

Answer 12

pyogranulomatous pneumonia - focal, multifocal, or regional

Question 13

why are clinical signs of r. equi pneumonia variable?

Answer 13

dependent on the stage & severity of pulmonary pathology

Question 14

what are the main clinical signs of r. equi pneumonia?

Answer 14

productive or non-productive cough, tracheal rattle - mucopurulent exudate in airways, nasal discharge

increased respiratory effort

cyanosis

Question 15

what clinical signs are associated with peracute r. equi pneumonia?

Answer 15

sudden onset of fever & respiratory distress & sudden death

Question 16

what clinical signs are associated with chronic r. equi pneumonia?

Answer 16

unthrifty & failure to grow at a normal pace

Question 17

what is included in extrapulmonary disorders?

Answer 17

metastatic sites of infection, immune-mediated disorders, & adverse effects pf treatment such as diarrhea & hyperthermia

Question 18

T/F: EPD are prevalent & can occur concurrent or independent of r. equi pneumonia

Answer 18

true

Question 19

why are EPDs bad?

Answer 19

challenging to detect ante-mortem

can negatively affect case outcome despite successful treatment of pneumonia

Question 20

how is the prognosis of r. equi different with EPD?

Answer 20

foals with EPD have a lower survival rate

Question 21

what are some EPDs that carry a poor prognosis?

Answer 21

uveitis, abdominal abscesses, septic synovitis/osteomyelitis

Question 22

why is identifying EPDs important?

Answer 22

awareness & recognition of them help vets better advise their clients regarding treatment & outcome

Question 23

what causes diarrhea in foals?

Answer 23

r. equi infection of gi tract or adverse effect of macrolide therapy

Question 24

what is seen on necropsy of a foal with ulcerative enterotyphlocolitis?

Answer 24

ulcerative, pyogranulomatous lesions of small intestines, cecum, colon with intralesional bacteria & positive r. equi culture

Question 25

what lesion is seen here?

Answer 25

ulcerative enterotyphlocolitis

Question 26

in foals with r. equi gi infections, what were the clinical signs?

Answer 26

only 40% had diarrhea, 30% had failure to grow, & 90% have concurrent abdominal abscess or lymphadenopathy

Question 27

how is abdominal lymphadenitis diagnosed in foals?

Answer 27

enlarged abdominal lymph nodes & lymphangiectasia ultrasound necropsy

Question 28

what lesion is seen?

Answer 28

abdominal lymphadenitis

Question 29

what lesion is seen?

Answer 29

abdominal lymphangiectasia

Question 30

what clinical signs are associated with abdominal abscessation?

Answer 30

diarrhea, failure to grow, recurrent colic large abscesses with caseous center

Question 31

how is abdominal abscessation diagnosed?

Answer 31

abdominal ultrasound, u/s guided aspirates for culture & cytology, & necropsy

Question 32

what lesion is seen?

Answer 32

abdominal abscessation

Question 33

what is the prognosis of foals with abdominal abscessation?

Answer 33

very poor

Question 34

how is abdominal abscessation treated?

Answer 34

long term antimicrobials & surgical excision/drainage (unsuccessful because of adhesions)

Question 35

how is peritonitis diagnosed?

Answer 35

ultrasound & peritoneal fluid analysis

Question 36

what are the common concurrent EPD seen in foals with peritonitis from r. equi?

Answer 36

abdominal abscesses, abdominal lymphadenopathy, & ulcerative enterotyphlocolitis

Question 37

what is pyogranulomatous hepatitis?

Answer 37

pyogranulomatous microabscesses in the liver

Question 38

how is pyogranulomatous hepatitis diagnosed?

Answer 38

no elevations in liver enzymes, ultrasound, & necropsy

Question 39

what lesion is seen on ultrasound?

Answer 39

pyogranulomatous hepatitis

Question 40

what are the suggested causes of uveitis in foals with r. equi?

Answer 40

immune-mediated & septic animals septic complication associated with the severity of lung disease

Question 41

how is uveitis diagnosed?

Answer 41

ophthalmologic exam - aqueous flare, hypopyon, iris discoloration, miosis, & blindness

Question 42

how is uveitis treated?

Answer 42

topical steroids & atropine TPA

Question 43

what is the prognosis uveitis?

Answer 43

associated with non-survival

Question 44

what percentage of foals are affected by polysynovitis when they have r. equi?

Answer 44

25%

Question 45

what is polysynovitis?

Answer 45

effusion of 1 or more synovial structures without lameness - often bilaterally symmetrical deposition of immune complexes in synovial membranes

Question 46

what joints are commonly affect in polysynovitis?

Answer 46

tarsocrural, carpal, front & rear fetlocks, stifle median number of joints affected = 5

Question 47

how is polysynovitis diagnosed?

Answer 47

usually recognized based upon clinical signs

Question 48

how is polysynovitis treated in foals?

Answer 48

generally none - resolves with the resolution of pneumonia

Question 49

how is septic synovitis diagnosed?

Answer 49

synovial effusion with lameness & synovial fluid analysis - 10% of foals affected

Question 50

what is the prognosis of foals with r. equi associated septic synovitis?

Answer 50

poor prognosis

Question 51

what is the treatment for foals with r. equi associated septic synovitis?

Answer 51

joint lavage systemic antimicrobials intra-articular antimicrobials regional limb perfusion

Question 52

what are the clinical signs of mediastinal lymphadenopathy?

Answer 52

enlargement of the mediastinal lymph nodes, respiratory distress, respiratory noise

Question 53

how is mediastinal lymphadenopathy diagnosed?

Answer 53

rads, ultrasound, & necropsy

Question 54

what disease process is shown on this rad?

Answer 54

mediastinal lymphadenopathy

Question 55

what is the prognosis of foals with r. equi bacteremia?

Answer 55

poor prognosis

Question 56

what lymph nodes are typically affected with peripheral lymphadenopathy in foals with r. equi?

Answer 56

submandibular, retropharyngeal, & inguinal lymph nodes

Question 57

what clinical signs are associated with vertebral body osteomyelitis in foals with r. equi?

Answer 57

fever, stiffness, pain, neuro signs, cauda equina syndrome

Question 58

what is seen on this rad?

Answer 58

cauda equina syndrome

Question 59

what lesion is pictured?

Answer 59

paravertebral abscess

Question 60

what is the treatment of hyperthermia in foals with r. equi?

Answer 60

water or alcohol baths environmental control

Question 61

what are the clinical features of hyperthermia in foals with r. equi?

Answer 61

body temperature > 104, tachypnea, tachycardia, respiratory distress adverse effect of macrolide treatment - environmentally dependent

Question 62

what is the gold standard for diagnosing r. equi pneumonia in foals?

Answer 62

isolation of r. equi from a tracheobronchial aspirate from a foal with clinical signs of pneumonia

Question 63

how is a diagnosis of r. equi pneumonia supported?

Answer 63

cytologic evidence of septic inflammation & gram positive pleomorphic coccobacilli in TBA specimens radiographs or ultrasound of pulmonary abscessation or consolidation

Question 64

when should r. equi be considered as a differential?

Answer 64

any infectious disease during age period 3-24 weeks history of endemic farm should raise clinical index of suspicion

Question 65

what may be heard on thoracic auscultation of a foal with r. equi pneumonia?

Answer 65

crackles, wheezes, referred large airway sounds, & attenuated bronchovesicular sounds

Question 66

what may be some clin path findings in a foal in r. equi?

Answer 66

leukocytosis with mature neutrophilia, WBC useful as a screening method hyperfibrinogenemia thrombocytosis serum amyloid a serum chemistries - effects of hypoxemia & metastatic infection arterial blood gas

Question 67

what does r. equi look like on cell culture?

Answer 67

irregularly round, smooth, semitransparent, mucoid, salmon-pink colonies

Question 68

what bacteria is this?

Answer 68

r. equi

Question 69

why can false negatives occur on culture for r. equi?

Answer 69

prior antimicrobial therapy overgrowth of other bacteria

Question 70

why can false positives occur on culture for r. equi?

Answer 70

environmental contamination & growth of avirulent isolates

Question 71

what is PCR used for in r. equi infections?

Answer 71

high sensitivity & specificity for detecting virulent r. equi in tba fluid of affected foals - should not replace culture but used in conjunction

Question 72

what is culture needed for r. equi?

Answer 72

antimicrobial susceptibility testing

Question 73

T/F: PCR & cultures run on nasal/nasopharyngeal swabs has a high sensitivity for detecting r. equi

Answer 73

false - poor sensitivity

Question 74

why are thoracic rads helpful in diagnosing r. equi infections?

Answer 74

valuable for detecting pulmonary lesions, images can be taken in the field, diagnostic/screening values assessment of treatment

Question 75

what patterns are commonly seen on thoracic rads of foals with r. equi?

Answer 75

interstitial & alveolar patterns

Question 76

why is ultrasound useful for foals with r. equi?

Answer 76

detects, localizes, & characterizes peripheral lung consolidations & abscesses, more sensitive than rads, & useful for detection of clinical & subclinical pulmonary disease

Question 77

what are the disadvantages of using ultrasound for foals with r. equi?

Answer 77

can't penetrate air-filled lung - can miss deep lung or mediastinal abscesses

Question 78

what abnormalities are seen on ultrasound of foals with r. equi pneumonia?

Answer 78

comet tails consolidation - architecture of lung is intact abscessation - architecture is lost pleural effusion