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32 Cards in this Set
- Front
- Back
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What is the causative agent of blastomycosis?
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Dimorphic fungus Blastomyces dermatitidis
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How does blastomyces exist in infected tissue? How does it reproduce?
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Organism is a thick-walled yeast that reproduces by budding
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What is the primary geographic locations of blastomycosis?
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Mississippi & Ohio River valleys as well as the Missouri, Tennessee and St. Lawrence Rivers, the Southern great lakes and southern mid-atlantic states
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What triggers liberation of blastomyces from the soil?
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Rain, dew and activities such as digging or excavation
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What is the seasonal variation related to blastomycosis?
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Wisconsin: late spring to late fall
South: no seasonal variation |
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How are mammals infected with blastomyces?
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Inhalation of conidiophores from environment and rarely from direct inoculation (=local draining lesion that doesn't heal)
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When does transformation to the yeast form of blastomyces occur?
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Occurs after phagocytosis of conidia by alveolar macrophages
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What is the immune systems response to phagocytosis of conidia?
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There is marked pyogranulomatous inflammation, which may contain the disease locally
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How does systemic dissemination of blastomyces occur?
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Some phagocytized yeast may be carried to the interstitium, gaining access to the lymphatics and vascular system= systemic
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How common is blastomycosis in dogs compared to people?
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10 times more common in dogs
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What signalment of dogs is predisposed to blastomycosis?
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Male hunting breeds, 2 to 4 years old
-breed prevalence more related to risk of exposure than susceptibility |
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Proximity to ______ is a risk factor for blastomycosis.
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Rivers
-95% of affected WI dogs lived within 400 m of water |
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Is blastomycosis more common in dogs or cats?
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Infection in cats uncommon
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What is the most common clinical signs of blastomycosis?
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Pulmonary signs in about 75% of cases
-severe fungal pneumonia---> dyspnea & cough -soft or loud cough depending on if hilar lymphadenopathy (loud) or just pneumonia (soft) |
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What organs are commonly affected by blastomycosis in dogs?
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-lungs and lymph nodes****
-eyes, skin, bones, SQ tissues, prostate |
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What organs are commonly affected in cats with blastomycosis?
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-skin and SQ tissues
-eye, CNS & lnns |
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Cachexia is common in patients with blastomycosis that have _____ signs.
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Respiratory
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What are the clinical signs of cutaneous involvement of blastomycosis?
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Single or multiple papules, nodules or plaques that can ulcerate and drain a serosanguinous to purulent exudate
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What clinical signs mean a poor prognosis in patients with blastomycosis? Why?
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If in the eye or brain= poor prognosis because harder to eliminate the disease here due to barriers
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What clinical signs indicate a poor prognosis for return of function of the affected eye?
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Dogs w/ blindness or glaucoma
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What is a clinical sign of bone or joint involvement in dogs with blastomycosis?
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Lameness
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How do the clinical signs of cats with blastomycosis vary from those seen in dogs?
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Similar, but more likely to develop large abscesses and have neurological signs
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What lab abnormalities are found on chemistry and hematology of animals with blastomycosis?
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Non-specific
-Hypercalcemia in 10% |
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Are chest radiographs very helpful in patients suspected of having blastomycosis?
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Yes, even in the absence of pulmonary signs
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What radiographic changes are seen on chest radiographs of an animal with blastomycosis? (3)
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1) Nodular pattern
-may appear similar to diffuse metastasis 2) Diffuse interstitial or alveolar pattern 3) Occasionally-limited to a single consolidated lung |
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What are 5 diagnostic methods that can be used to diagnose blastomycosis?
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1) Demonstration of organism by cytology
2) Demonstration of organism by histopathology 3) Urine antigen test -works well 4) Fungal culture -seldom necessary 5) Serology |
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How can the blastomyces organism be demonstrated by cytology? (3)
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1) Impression smears from draining skin lesions
2) FNA of skin nodules, lymph nodes, bones or other affected tissues 3) Airway washings |
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When is serology useful for diagnosing blatomycosis?
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in cats, lacks sensitivity & specificity in dogs
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How long should treatment of blastomycosis continue?
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Continue for 30 days past resolution of all clinical signs (or a minimum of 60 d)
-common duration= 6 mo + |
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When do you want to use Fluconazole over itraconazole in an animal with blastomycosis?
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When clinical signs are present in CNS and eye bc has better penetration
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Why is amphotericin B not a first choice for treating blastomycosis?
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Administered IV
High rate of nephrotoxicity |
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What is the prognosis for blastomycosis?
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75% survival w/ treatment
-patients that do poor are those w/ severe pulmonary involvement -relapse occurs in 1 out of 5 |
