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Small Animal Medicine II > Malassezia Dermatitis > Flashcards

Malassezia Dermatitis Flashcards

1
Q

What is Malassezia pachydermatis? What stains are used for diagnosis?

A

lipid-dependent, lipophilic yeast (lacks fatty acid synthase) that is a normal inhabitant of canine skin –> broad-based, budding, round, peanut-shaped

  • Diff-Quik
  • methylene blue
  • Wright’s stain
  • Gram +
  • silver stain
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2
Q

What 4 factors add to pathogenicity of Malassezia?

A
  1. environment - humidity, temperature
  2. immunity - age, disease
  3. breeds - Basset Hound, Boxer, Dachshund, American Cocker Spaniel
  4. concurrent disease - atopy

+/- skin lipid content drives species composition

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3
Q

What diseases are associated with Malassezia dermatitis in dogs and cats?

A
  • ALLERGIES - atopy, adverse food reactions, flea allergy
  • ENDOCRINE - hypothyroidism, Cushing’s, DM
  • CORNIFICATION - seborrhea, epidermal dysplasia (WHWT)
  • SYSTEMIC - liver/renal disease

systemic illness, allergies

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4
Q

What 5 pathogenic mechanisms do Malassezia contain?

A
  1. activation of alternate pathway of complement
  2. hypersensitivity to fungal allergens - IgE, IgG
  3. produces zymosan and phospholipase that contribute to inflammation and pruritus
  4. produces a biofilm
  5. symbiotic relationship with staphylococci
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5
Q

Where in the skin will Malassezia infection be found?

A

outer layer of skin –> enzymes absorbed deeper

  • not normally in follicles or deeper
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6
Q

What are 3 key historical features of Malassezia dermatitis? What historical complaints are associated?

A
  1. severe progressive pruritis
  2. generally non-seasonal - heat exacerbation, wet weather, snow
  3. partially responsive to glucocorticoids

licking feet, rubbing face, perianal pruritus, otitis externa, weight loss –> seems like atopy out of control

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7
Q

What are the 4 major differential diagnoses for intense pruritus?

A
  1. scabies
  2. Malassezia dermatitis
  3. flea allergy dermatitis
  4. familial seborrhea - Cocker Spaniel
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8
Q

What are 5 lesions associated with Malassezia dermatitis?

A
  1. erythematous scaling and crusting
  2. lichenified, hyperplastic, hyperpigmented skin
  3. alopecia
  4. generalized enlarged LNs
  5. otitis
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9
Q

Malassezia dermatitis:

A

scaling and crusting

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10
Q

Malassezia dermatitis:

A

lichenification, alopecia

  • swab edges, not thick skin
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11
Q

Malassezia dermatitis:

A

thin-skinned areas commonly affected –> inguinal, axilla, toe webs

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12
Q

Malassezia dermatits:

A

classical - interdigital skin, dorsal AND ventral

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13
Q

Malassezia, WHWT:

A
  • depressed, lethargic
  • thickened skin
  • odor
  • otitis
  • WHWY armadillo syndrome
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14
Q

Malassezia, Himalayan:

A

thick, waxy debris

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15
Q

What are the two major trouble areas associated with Malassezia dermatitis?

A
  1. facial/lip folds
  2. paws - claw folds, interdigital skin, waxy buildup full of yeast common at nail beds

+/- thin-skinned areas

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16
Q

What cat breed is predisposed to developing Malassezia dermatitis? What is it associated with? What 3 species are most commonly seen?

A

Devon Rex –> allergy, seborrhea, systemic illness

  1. M. pachydermatis (50%)
  2. M. furfur (40%)
  3. M. sympodialis (10%)
17
Q

What 7 steps are recommended while diagnosing Malassezia dermatitis?

A
  1. dermatological history
  2. PE and dermatologic examinations
  3. dermatology data base
  4. allergy testing - atopy, food
  5. CBC/chem/UA
  6. endocrine function tests
  7. immune system evaluation
18
Q

What 3 locations should be sampled for Malassezia dermatitis? What areas are avoided?

A
  1. lip folds
  2. dorsal/ventral interdigital spaces
  3. axillary, perivulvar, perianal, and facial folds

severely lichenified skin

19
Q

Malassezia cytology scale:

A

most useful for quality control, NOT if treatment is indicated

20
Q

Malassezia:

A

Diff-Quik stains all stages

21
Q

What secondary condition commonly needs to be treated in cases of Malassezia dermatitis? What are 2 options?

A

bacterial infections commonly associated with primary conditions (atopy)

  1. TOPICAL - BPO
  2. SYSTEMIC - anti-staphylococcal (Cephalexin, Cefpodoxime/Simplecef)
22
Q

What 6 active ingredients are beneficial topical therapies recommended for cases of Malassezia dermatitis?

A
  1. selenium
  2. disulfide
  3. chlorhexidine
  4. miconazole, clotrimazole, enilconazole, ketoconazole
  5. nystatin
  6. lime sulfur
23
Q

What 4 things alter frequency of topical therapy needed for cases of Malassezia dermatitis?

A
  1. severity of disease
  2. location of infection
  3. owner compliance
  4. other therapy - systemic
24
Q

What are 2 options for degreasing shampoos in treating Malassezia dermatitis?

A
  1. selenium sulfide
  2. benzoyl peroxide - good for staph

can strip lipid layer chronically

25
Q

What are 4 keys to successful shampoo therapy in cases of Malassezia dermatitis?

A
  1. proper contact time
  2. luke-cool water
  3. frequency - 3x/week as sole therapy, 1-2x/week as adjunctive therapy
  4. alternate with an anti-bacterial shampoo (BPO)
26
Q

How are wipes used in treating Malassezia dermatitis?

A

can be used daily for lip folds, facial folds, perivulvar region, perianal region, and feet (trouble spots!) for 7-14 days

  • 1-2x/week for maintenance and prevention
  • can add other products (sprays) to extend spectrum and improve effectiveness
27
Q

What are 4 options for topical therapy in cases of Malasezzia dermatitis?

A
  1. Ketoconazole - dogs
  2. Itraconazole - cats
  3. Fluconazole - dogs, cats
  4. Terbinafine
    - usually used in combination with topicals
    - recommended having a biochemical baseline (liver) performed

21-30 days

28
Q

What are 3 indications for systemic treatment for Malassezia dermatitis?

A
  1. owner can’t/won’t bathe or manage topicals
  2. severe infections
  3. animals develop reactions to topical agents
29
Q

What 3 side effects are associated with Terbinafine usage?

A
  1. GI
  2. panting
  3. elevated hepatic enzymes
30
Q

What does Malassezia dermatitis treatment depend on? How are generalized areas and trouble spots treated?

A

location of infections - generalized vs. focal

  • GENERALIZED - bath weekly until resolved (determined by cytology) with pipes, mousse, and sprays to treatment of trouble spots
  • TROUBLE SPOTS - wipes, mousse, sprays daily for 7-10 days, then 1-3 weeks
31
Q

When is maintanence started for cases of Malassezia dermatitis?

A

initiate maintainence after clearance –> bathing weekly or PRB (chlorhexidine, azole), regular uses of wipes and sprays for trouble spots

Small Animal Medicine II (57 decks)

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