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Systemic Pathology II > Wildlife Diseases > Flashcards

Wildlife Diseases Flashcards

1
Q

What causes myxomatosis? What 3 species are most affected?

A

dsDNA virus, Leporipoxvirus = bighead, mosquito disease, mixi

  1. American rabbits - enzootic, mild disease
  2. European rabbits (domestic pets in USA and Australia) - epizootic, severe disease
  3. hares (Lepus spp.)
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2
Q

How is myxomatosis transmitted? What is its pathogenesis?

A

ARTHROPODS - mosquitoes (America), fleas (Europe)

  • virus infects epithelial (mucosal) cells and fibroblasts and locally proliferates into myxomas (pseudo-tumors)
  • virus then infects lymphocytes and spreads to the LNs resulting in viremia from leukocyte trafficking
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3
Q

How does myxomatosis result in myxomas?

A

virus infects epithelium and secretes myxoma growth factor, EGF

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4
Q

What are the 2 main results from myxomatosis?

A
  1. severe lesions may result in death due to emaciation, blindness, predation, and other trauma due to tumor growth or secondary bacterial infection (conjunctivitis)
  2. less severe (American) form allows for myxoma regression
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5
Q

How do the clinical signs of myxomatosis compare in American and European rabbits?

A

AMERICAN = mild disease with localized myxomas forming 4-8 days post-exposure and eventual regression

EUROPEAN = large myxomas form 3-4 dpe mostly around the eyes and nose with suppurative blepharoconjunctivitis, dermatitis, peianal edema, and a high mortality rate

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6
Q

What results from atypical myxomatosis?

A

viral interstitial pneumonia

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7
Q

Myxomatosis, European rabbit:

A
  • more severe
  • swelling and redness around the eyelids due to secondary conjunctivitis
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8
Q

Myxomatosis, European rabbit disease progression:

A
  • more severe
  • suppurative exudate
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9
Q

What are the 2 major gross findings with myxomatosis?

A
  1. subcutaneous mucinous (gelatinous) masses particularly on the face and perineum = myomas
  2. mucopurulent blepharoconjunctivitis with nasal discharge
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10
Q

What are some additional gross findings with myxomatosis?

A
  • interstitial pneumonia with edema and hemorrhage (atypical)
  • edema of perineum
  • hemorrhages in skin, heart, GIT, kidney, LN, and testes
  • splenomegaly
  • LN edema
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11
Q

Myxomatosis, myxoma:

A

mucinous (gelatinous) masses around eyes and nose

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12
Q

Atypical myxomatosis:

A
  • interstitial pneumonia
  • frothy discharge in trachea = edema
  • hemorrhage
  • rib impressions
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13
Q

What are the 2 major histopathological findings in myxomatosis? What are 2 other findings?

A
  1. epithelial hyperplasia with ballooning degeneration and eosinophilic IC viral inclusions
  2. myxoma cells (mesenchymal spindloid to stellate) separated by abundant myxomatous matrix in dermis
  • lymphoid depletion within spleen and LN
  • focal areas of necrosis in LN, pneumocytes, spleen, and centrilobular hepatocytes
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14
Q

Myxomatosis, epithelial hyperplasia:

A
  • thickened epidermis with collagen fibers separated by mucin
  • can be stained with Alcian blue to picture
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15
Q

Myxomatosis, ballooning degeneration:

A
  • epithelial hyperplasia and hyperkeratosis
  • presence of heterophils
  • ballooning degeneration with nucleus pushed to the top
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16
Q

Myxomatosis, inclusion bodies:

A

eosinophilic IC IB

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17
Q

Myxomatosis, IC inclusion body:

A

eosinophilic!

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18
Q

Myxomatosis, myxoma cells:

A
  • found within myxomatous matrix in the dermis
  • spindle/stellate
  • green = IC inclusion
19
Q

How is myxomatosis diagnosed? Prevented/controlled?

A

characteristic clinical signs, gross lesions, and histopath + PCR, EM (dumbbell-shaped)

  • some vaccinations available
  • keep mosquitoes and fleas away from rabbits
20
Q

What causes snake fungal disease? What species is mostly affected?

A

Ophidiomyces ophiodiicola - hibernation blisters/sores

rattlesnakes especially in Midwestern and Eastern USA —> Eastern massasauga rattlesnakes

21
Q

What are the 5 steps to snake fungal disease pathogenesis?

A
  1. Ophidiomyces ophidiodiicola breaches the stratus corneum through abrasions and invades the epidermis by breaking down keratin and ECM with enzymes of ammonia release by urease
  2. snake mounts an immune response, recruiting heterophils, macrophages, and multinucleated giant cells (+ edema)
  3. epidermis becomes necrotic (yellow/brown crusts) and detaches causing ulcerations/erosion
  4. fungus proliferates in the epidermis +/- dermis, subcutis, muscle, and bone
  5. granulomas develop in skin and deeper tissue
22
Q

What are the main 2 results of snake fungal disease?

A
  1. systemic dissemination in captive snakes - not common in wild, rarely live long enough
  2. death due to emaciation, predation, and secondary bacterial infection
23
Q

What are the 6 clinical signs associated with snake fungal disease?

A
  1. yellow/brown plaques*
  2. increased moulting frequency (may clear infection)
  3. retained spectacles or scales (dysecdysis)
  4. altered behavior —> behavior fever where snake moves to warm areas to increase body temperature (gives itself a fever)
  5. deformed head
  6. emaciation
24
Q

Snake fungal disease:

A
  • yellow/brown plaques
  • deformed head
25
Q

Snake fungal disease:

A
  • yellow/brown plaques
  • deformed head
  • retained and opaque spectacles that are usually lost with molting
26
Q

Snake fungal disease, head:

A

deformed with yellow/brown plaque

  • retained spectacle = trouble seeing and eating = emaciation
27
Q

What 2 histopathology lesions are characteristic of snake fungal disease?

A
  1. epidermal erosion/ulceration with granulomatous inflammation (MGC, MQ) surrounded by lymphocytes, plasma cells, heterophils, and fibroblasts
  2. granulomas with fungal hyphae
28
Q

Snake fungal disease, granuloma:

A

MGC + MQ with fungal hyphae (branches stain with silver and PAS)

29
Q

Snake fungal disease, fungal hyphae:

A
30
Q

How is snake fungal disease diagnosed? What must be ruled out? How can this be done?

A

charcteristic clincal signs, gross lesions, and histopathology + PCR, fungal culture

mycobacteriosis (fungi may be secondary invaders) —> stain positive on Acid Fast, unlike fungi

31
Q

How can snake fungal disease be prevented/controlled?

A
  • field hygiene (disinfect equipment, change gloves between snakes)
  • population health
  • CAPTIVE: quarantine, antifungal vapors
32
Q

What are 2 causes of chytridiomycosis? What species are most affected by each?

A
  1. Batrachochytrium dendrobatidis - frogs
  2. Batrachochytrium salamandrivorans - salamanders
33
Q

What is the lifecycle of Batrachochytrium dendrobatidis like?

A
  • spores are able to swim/move within the skin or soil
  • spores aggregate and eventually burst from their cyst
  • zoospores are able to then infect the host
34
Q

What are the 5 steps to chytridiomycosis pathogenesis? What is able to happen at the end of the cycle?

A
  1. motile zoospores invade keratin of the stratum corneum
  2. zoosporangia develop in epidermal cells (keratinocytes), where they are able to mature and release zoospores
  3. epidermis thickens (hyperplasia/hyperkeratosis) with minimal to absent inflammation
  4. respiration and electrolyte balance are altered, leading to hyperkalemia impacting myocardial contractility (amphibian skin is important for electrolyte balance)
  5. death

zoospores are able to live in the environment or skin of other amphibians (facultative pathogen)

35
Q

What are 4 clinical signs associated with chytridiomycosis caused by Bd? What animals are most susceptible?

A
  1. skin hyperermia (red leg is NOT a disease) likely due to a secondary bacterial infection and skin thickening requiring more blood supply
  2. depression, anorexia
  3. increased skin shedding without it being consumed
  4. seizures due to electrolyte imbalance

froglets (just went through metamorphosis)

36
Q

What are the 3 clinical signs associated with chytridiomycosis caused by Bsal?

A
  1. skin erosion to ulceration
  2. depression, anorexia
  3. increased skin shedding
37
Q

What clinical signs are associated with frogs infected by Bsal? Which are more susceptible?

A

skin hyperemia or nothing at all

froglets - have a much higher concentration of keratin compared to tadpoles to acclimate to land

38
Q

Chytridiomycosis, Bsal

A

skin erosion to ulceration

39
Q

What histopathological lesions are associated with chytridiomycosis?

A

Bd = epidermal hyperplasia and hyperkeratosis with occasional inflammation

Bsal = epidermal hyperplasia and erosion to ulceration

40
Q

Chytridiomycosis, Bd, histo:

A

epidermal hyperplasia/hyperkeratosis + zoosporangia

41
Q

Chytridiomycosis, Bd, epidermis:

A
  • hyperplasia, hyperkeratosis
  • zoosporangia
42
Q

Chytridiomycosis, Bsal:

A

epidermal hyperplasia with ulceration

43
Q

How is chytridiomycosis diagnosed?

A

PCR on skin swabs + histopathology for new areas and Bsal in North America

44
Q

How is Chytridiomycosis prevented/controlled?

A
  • field hygiene
  • clean trade
  • population health*

(ESPECIALLY FOR BSAL —> high mortality rate to North American salamanders with a large species diversity and richness)

Systemic Pathology II (24 decks)

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