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SA DX & TX I > Exam 2 - Canine & Feline Fungal Disease > Flashcards

Exam 2 - Canine & Feline Fungal Disease Flashcards

1
Q

why are blasto & histo similar to one another?

A

both are dimorphic fungi

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2
Q

where is blastomyces dermatitidis found in the environment?

A

sandy, acidic soil near water - especially near deep soil layers

north america - especially eastern river valleys

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3
Q

where is histoplasma capsulatum found in the environment?

A

soil rich in organic nitrogen - bird & bat feces

temperate/sub-tropical regions of the world

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4
Q

does blasto primarily affect dogs or cats?

A

dogs

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5
Q

does histo primarily affect dogs or cats?

A

cats

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6
Q

T/F: asymptomatic infections are likely in both blasto & histo

A

false - rare in blasto & may occur in histo

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7
Q

what organism has this regional distribution?

A

blasto

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8
Q

what organism has this region distribution?

A

histo

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9
Q

what is the pathogenesis of blasto?

A

inhalation of spores - deposition in terminal airways where they turn into yeasts

survival in phagocytes & disseminate to the eyes, bone, & skin

rare wound inoculation

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10
Q

what is the pathogenesis of histo?

A

inhalation of spores - deposition in terminal airways where they turn into yeasts

survival in macrophages & disseminate to the gi tract, eyes, skin, & bone

rare wound inoculation

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11
Q

T/F: histo may only affect the skin

A

true

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12
Q

what dogs are typically affected by blasto?

A

sporting, active dogs under 4 years of age

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13
Q

what dogs, if any, are affected by histo?

A

large, sporty ones - weimaraner, pointer, & brittany spaniels

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14
Q

what cats are typically affected by histo?

A

cats, even indoor only, younger than 4 years

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15
Q

what are the clinical signs associated with blasto?

A

severe weight loss, lethargy, exercise intolerance, lameness, coughing/dyspnea, ocular involvement, proliferative or draining skin lesions, & sometimes bone lesions

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16
Q

T/F: cats may have GI involvement when infected with blasto

A

true

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17
Q

what are the clinical signs of histo in dogs?

A

severe large bowel diarrhea, dogs may cough/dyspnea, & hepatomegaly

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18
Q

what are the clinical signs of histo typically seen?

A

lethargy, inappetence, weight loss, PLE, dyspnea, tachypnea, abnormal lung sounds, & enlarged liver/spleen/lymph nodes

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19
Q

what may be supportive of blasto in the patient’s history & physical exam?

A

water exposure

skin lesions, bone pain, & respiratory abnormalities

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20
Q

what is your big differential for an older dog with suspicious blasto?

A

osteosarcoma

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21
Q

what may be found on imaging that is supportive of a blasto diagnosis?

A

diffuse pulmonary disease often with lymphadenopathy

lytic & productive bone lesions & soft tissue swelling

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22
Q

what may be found on clin-path that may be supportive of a blasto diagnosis?

A

hypercalcemia of granulomatous disease, anemia of chronic inflammation, & hyperglobulinemia (polyclonal)

23
Q

what may be seen in the ocular exam in an animal with blasto?

A

granular changes in the retina

24
Q

what is the cytology/histology of blasto? what can you sample?

A

broad-based budding yeast with pyogranulomatous inflammation

FNA of lymph nodes, draining tract touch prep, bone biopsy

25
Q

T/F: if you see the organism on cytology when it comes to histo/blasto, it is 100% specific

A

true

26
Q

what may be supportive of histo in the patient’s history & physical exam?

A

may contain very little outdoor exposure

systemic & respiratory signs predominate in cats & gi signs predominate in dogs

27
Q

what may be found on imaging that is supportive of a histo diagnosis?

A

diffuse pulmonary disease with lymphadenopathy & gi mural thickening seen on endoscopy

28
Q

what may be found on clin-path that may be supportive of a histo diagnosis?

A

non-specific

hypercalcemia of granulomatous disease, anemia of chronic inflammation, polyclonal hyperglobulinemia, & hemophagocytosis in cats

29
Q

what is the cytology/histology of histo? what can you sample?

A

small intracellular yeast with basophilic center & poorly staining halo & pyogranulomatous inflammation

FNA of lymph nodes, rectal scrape, CSF tap

30
Q

what diagnostic test is >92% sensitive in diagnosing blasto & histo?

A

urine antigen EIA - enzyme immunoassay that amplifies detection

detects the antigen from the galactomannan in the cell wall excreted in the urine & it will end up in the urine regardless of the site of active infection

31
Q

T/F: urine EIA is often positive before serum EIA, but you should still consider sending both samples

A

true

32
Q

why can dilute urine mess with the antigen EIA for blasto & histo?

A

dilute urine dilutes the antigen in the urine as well & will produce a lower result

33
Q

in the setting of a relapse, _____ EIA is often positive before _____ EIA

A

urine

serum

34
Q

T/F: during treatment of blasto/histo, urine EIA drops even in patients that remain symptomatic

A

false - it stays positive longer

35
Q

why not culture blasto or histo?

A

risky for people!!! spores at environmental temps & yeasts at body temps!

36
Q

what is the mechanism of action for antifungals used in treating histo & blasto?

A

inhibit sterol synthesis - inhibits wall production

37
Q

why is the downside to fungistatic treatment of histo & blasto?

A

it doesn’t directly kill the fungus - long treatment times & very expensive

38
Q

what systemic antifungal has some of the worst side effects?

A

ketoconazole

39
Q

why use fluconazole if there are CNS signs?

A

it readily crosses the BBB

40
Q

T/F: itraconazole probably works more rapidly

A

true

41
Q

what is the mechanism of action of amphotericin b?

A

punches holes in ergosterol - kills fungal cell directly

42
Q

what are the cons of using amphotericin b?

A

IV only because poor oral absorption & marked nephrotoxicosis

43
Q

what is the mechanism of action of flucytosine?

A

pyrimidine antimetabolite that interferes with yeast DNA synthesis

44
Q

what is the mechanism of action of terbinafine?

A

allylamine ergosterol synthesis inhibitor with high concentrations reaching the skin & subcutaneous tissue

45
Q

what 2 key features predict the prognosis of blasto?

A
  1. severity of pulmonary involvement
  2. presence of CNS involvement
46
Q

what percentage of animals relapse after blasto treatment?

A

20-25%

47
Q

what is the treatment duration of blasto?

A

treat for one month beyond clinical cure - typically 4 to 6 months

48
Q

which is more treatable, histo or blasto?

A

histo

49
Q

what is a poor prognostic indicator of histo?

A

CNS involvement

50
Q

what is the treatment duration of histo?

A

treat for one month beyond clinical cure - typically 4 to 6 months

2 negative EIAs

51
Q

what are the most common systemic fungal infections seen in companion animals?

A

blasto & histo

52
Q

what is the first line of defense in treating blasto & histo?

A

azole therapy

53
Q

what can be a top differential for blasto/histo in systemically ill, wasting patients?

A

neoplasia

SA DX & TX I (59 decks)

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