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LA DX & TX I > Exam 2 - Rhodococcus Equi, Foal Pneumonia > Flashcards

Exam 2 - Rhodococcus Equi, Foal Pneumonia Flashcards

1
Q

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

A

pneumonia

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2
Q

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

A

rhodococcus equi

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3
Q

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

A

pneumonia

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4
Q

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

A

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

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5
Q

what is the etiology of rhodococcus equi?

A

pleomorphic, gram positive coccobacillus

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6
Q

what are the routes of infection for r. equi?

A

inhalation & ingestion

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7
Q

what is the pathogenesis of r. equi?

A

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

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8
Q

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

A

true

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9
Q

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

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

subclinical infection

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10
Q

when are foals most commonly affected by r. equi?

A

most are exposed early in life & become infected shortly after

clinical signs between 3-16 weeks of age

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11
Q

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

A

true

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12
Q

what kind of pneumonia does r. equi cause?

A

pyogranulomatous pneumonia - focal, multifocal, or regional

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13
Q

why are clinical signs of r. equi pneumonia variable?

A

dependent on the stage & severity of pulmonary pathology

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14
Q

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

A

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

increased respiratory effort

cyanosis

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15
Q

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

A

sudden onset of fever & respiratory distress & sudden death

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16
Q

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

A

unthrifty & failure to grow at a normal pace

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17
Q

what is included in extrapulmonary disorders?

A

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

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18
Q

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

A

true

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19
Q

why are EPDs bad?

A

challenging to detect ante-mortem

can negatively affect case outcome despite successful treatment of pneumonia

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20
Q

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

A

foals with EPD have a lower survival rate

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21
Q

what are some EPDs that carry a poor prognosis?

A

uveitis, abdominal abscesses, septic synovitis/osteomyelitis

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22
Q

why is identifying EPDs important?

A

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

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23
Q

what causes diarrhea in foals?

A

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

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24
Q

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

A

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

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25
Q

what lesion is seen here?

A

ulcerative enterotyphlocolitis

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26
Q

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

A

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

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27
Q

how is abdominal lymphadenitis diagnosed in foals?

A

enlarged abdominal lymph nodes & lymphangiectasia

ultrasound

necropsy

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28
Q

what lesion is seen?

A

abdominal lymphadenitis

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29
Q

what lesion is seen?

A

abdominal lymphangiectasia

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30
Q

what clinical signs are associated with abdominal abscessation?

A

diarrhea, failure to grow, recurrent colic

large abscesses with caseous center

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31
Q

how is abdominal abscessation diagnosed?

A

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

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32
Q

what lesion is seen?

A

abdominal abscessation

33
Q

what is the prognosis of foals with abdominal abscessation?

A

very poor

34
Q

how is abdominal abscessation treated?

A

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

35
Q

how is peritonitis diagnosed?

A

ultrasound & peritoneal fluid analysis

36
Q

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

A

abdominal abscesses, abdominal lymphadenopathy, & ulcerative enterotyphlocolitis

37
Q

what is pyogranulomatous hepatitis?

A

pyogranulomatous microabscesses in the liver

38
Q

how is pyogranulomatous hepatitis diagnosed?

A

no elevations in liver enzymes, ultrasound, & necropsy

39
Q

what lesion is seen on ultrasound?

A

pyogranulomatous hepatitis

40
Q

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

A

immune-mediated & septic animals

septic complication associated with the severity of lung disease

41
Q

how is uveitis diagnosed?

A

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

42
Q

how is uveitis treated?

A

topical steroids & atropine

TPA

43
Q

what is the prognosis uveitis?

A

associated with non-survival

44
Q

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

A

25%

45
Q

what is polysynovitis?

A

effusion of 1 or more synovial structures without lameness - often bilaterally symmetrical

deposition of immune complexes in synovial membranes

46
Q

what joints are commonly affect in polysynovitis?

A

tarsocrural, carpal, front & rear fetlocks, stifle

median number of joints affected = 5

47
Q

how is polysynovitis diagnosed?

A

usually recognized based upon clinical signs

48
Q

how is polysynovitis treated in foals?

A

generally none - resolves with the resolution of pneumonia

49
Q

how is septic synovitis diagnosed?

A

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

50
Q

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

A

poor prognosis

51
Q

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

A

joint lavage

systemic antimicrobials

intra-articular antimicrobials

regional limb perfusion

52
Q

what are the clinical signs of mediastinal lymphadenopathy?

A

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

53
Q

how is mediastinal lymphadenopathy diagnosed?

A

rads, ultrasound, & necropsy

54
Q

what disease process is shown on this rad?

A

mediastinal lymphadenopathy

55
Q

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

A

poor prognosis

56
Q

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

A

submandibular, retropharyngeal, & inguinal lymph nodes

57
Q

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

A

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

58
Q

what is seen on this rad?

A

cauda equina syndrome

59
Q

what lesion is pictured?

A

paravertebral abscess

60
Q

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

A

water or alcohol baths

environmental control

61
Q

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

A

body temperature > 104, tachypnea, tachycardia, respiratory distress

adverse effect of macrolide treatment - environmentally dependent

62
Q

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

A

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

63
Q

how is a diagnosis of r. equi pneumonia supported?

A

cytologic evidence of septic inflammation & gram positive pleomorphic coccobacilli in TBA specimens

radiographs or ultrasound of pulmonary abscessation or consolidation

64
Q

when should r. equi be considered as a differential?

A

any infectious disease during age period 3-24 weeks

history of endemic farm should raise clinical index of suspicion

65
Q

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

A

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

66
Q

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

A

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

67
Q

what does r. equi look like on cell culture?

A

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

68
Q

what bacteria is this?

A

r. equi

69
Q

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

A

prior antimicrobial therapy

overgrowth of other bacteria

70
Q

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

A

environmental contamination & growth of avirulent isolates

71
Q

what is PCR used for in r. equi infections?

A

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

72
Q

what is culture needed for r. equi?

A

antimicrobial susceptibility testing

73
Q

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

A

false - poor sensitivity

74
Q

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

A

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

assessment of treatment

75
Q

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

A

interstitial & alveolar patterns

76
Q

why is ultrasound useful for foals with r. equi?

A

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

77
Q

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

A

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

78
Q

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

A

comet tails

consolidation - architecture of lung is intact

abscessation - architecture is lost

pleural effusion

LA DX & TX I (45 decks)

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