Dermatology

Question 1

How do we go about diagnosing dermatological problems?

Answer 1

Full history
Physical examination
Problem list
Differential diagnoses
Diagnostic plan

Question 2

What diagnostic techniques are there for dermatological problems?

Answer 2

Acetate tape for cytology
Skin scrapings (deep/superficial)
Impression smears
Flea comb
Trichogram

Question 3

How do we diagnose dermatophytosis?

Answer 3

Microsporum canis isolates have pteridine which makes fluorescence
Left with UV lamp for 5 mins before observing in a darkened room
Microscopy requires experience to see spores
Test medium = lactophenol cotton blue preparation
Culture usually requires 2 weeks at room temp.

Question 4

What are the topical therapies available for dermatophytosis?

Answer 4

Shampoos e.g. Malaseb, Microbex
Dips e.g. enilconazole (Imaverol)
Washed twice weekly and rinsed after 10 mins throughout treatment period

Question 5

What systemic therapies are available for dermatophytosis?

Answer 5

Itraconazole - treat for 7 days x3 with 7 days between each (cats = 5 mg/kg/day suspension)
Ketoconazole (dogs = 10 mg/kg/day tablets)

Question 6

How can we treat an environment contaminated with dermatophytosis?

Answer 6

Grooming utensils, bedding and collars removed/thrown away
Washable items soaked in antifungal disinfectant, then washed at at least 50 degrees
Daily vacuuming and disposal of contents
Chemicals (bleach 1:100, enilconazole, Virkon 1%)

Question 7

What are the indications for a skin biopsy?

Answer 7

Neoplasia - suspected or obvious
Unusual or serious generalised dermatosis
Condition poorly responsive to therapy
Other diagnostic tests not helpful
Vesicles, bullae, erosions, ulcerations

Question 8

How do we carry out a skin biopsy?

Answer 8

Local anaesthetic + sedation / GA
Clip hair, do not prep skin surface
Choose multiple sites, fully developed lesions (avoid chronic or traumatised)
Punch 4/6/8mm or excision
Histopathology, culture, cytology

Question 9

What results can we get from a skin biopsy?

Answer 9

Diagnostic
Compatible with clinical diagnosis
Not compatible with clinical diagnosis
Non-diagnostic

Question 10

What “flare” factors may start the itch-scratch cycle?

Answer 10

Bacterial and yeast infection
Fleas
Dry skin and low humidity/sweating
Psychological factors (stress, anxiety, boredom?)

Question 11

Describe the Visual Analog Scale for clinical assessment of pruritus.

Answer 11

Clinician/owner carried out
Licking, rolling, rubbing
Specifically question about foot licking and face rubbing - may be interpreted as ‘grooming’
Head shaking may be solely interpreted as ‘ear disease’ rather than generalised pruritus

Question 12

What are the clinical signs of canine atopic dermatitis?

Answer 12

Associated with self-trauma and secondary bacterial and Malassezia infections - alopecia, erythema, excoriation, hyperpigmentation and lichenification

Question 13

How can we diagnose canine atopic dermatitis?

Answer 13

By ruling out other conditions that cause pruritus

Intradermal and blood testing used to select allergens for immunotherapy

Question 14

What are the indications for allergen testing?

Answer 14

DO NOT confirm diagnosis of atopic disease
May identify allergens of clinical significance
Provide basis for allergen-specific immunotherapy (ASIT)/allergy vaccine/desensitisation

Question 15

What are the clinical signs of pyoderma?

Answer 15

Intraepidermal pustules
Primary and secondary lesions
Annular lesion with peeling epidermal collarette
Antibiotic responsive
Underlying causes = ectoparasitism, allergy, endocrinopathies

Question 16

Describe pyoderma therapy.

Answer 16

Superficial usually readily respond within 3-4 weeks
Immune response to Staphylococci antigens?
Important to treat bacterial infections thoroughly before commiting to investigations for allergies or endocrinopathies

Question 17

How are topical therapies helpful for pyoderma?

Answer 17

Remove crust, scale and exudate from skin surface
Reduce number of bacteria
Promote drainage of deeper lesions
Reduce pain and pruritus

Question 18

How are topical therapies used to treat pyoderma?

Answer 18

Clip coat
Used 2-3 times weekly until clinical remission
Products usually contain chlorhexidine
Aim for 10 min soak before rinsing thoroughly

Question 19

What is Malassezia?

Answer 19

Malassezia pachydermatis
Opportunistic yeast pathogen
Normally resident in external ear canal, chin, perioral and interdigital areas

Question 20

What factors predispose an animal to Malassezia infection?

Answer 20

Alterations in skin microclimate (sebum production, moisture)
Allergic and bacterial skin disease

Question 21

What are the clinical signs of Malassezia infection?

Answer 21

Generalised with ventral distribution or localised to feet, face, skin folds or perianal region
Pruritus common and severe
Erythema, scale, hyperpigmentation, oily scale and malodour

Question 22

How do we diagnose Malassezia infection?

Answer 22

Impression smears with a dry swab/direct slide contact
Acetate strip preparations
Culture
Serology - not recommended

Question 23

What therapies are available to treat Malassezia infection?

Answer 23

Topical therapies, twice weekly bathing with miconazole/chlorhexidine shampoos
Keratolytic shampoos e.g. selenium sulphide
Systemic therapy with itraconazole 5 mg/kg SID for 7 days

Question 24

THIS CARD IS A REMINDER TO STUDY ENDO/ECTOPARASITES:)

Answer 24

VN Week 10 - Dermatological Infections and Infestations