Dermatology Flashcards
How do we go about diagnosing dermatological problems?
Full history Physical examination Problem list Differential diagnoses Diagnostic plan
What diagnostic techniques are there for dermatological problems?
Acetate tape for cytology Skin scrapings (deep/superficial) Impression smears Flea comb Trichogram
How do we diagnose dermatophytosis?
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.
What are the topical therapies available for dermatophytosis?
Shampoos e.g. Malaseb, Microbex
Dips e.g. enilconazole (Imaverol)
Washed twice weekly and rinsed after 10 mins throughout treatment period
What systemic therapies are available for dermatophytosis?
Itraconazole - treat for 7 days x3 with 7 days between each (cats = 5 mg/kg/day suspension)
Ketoconazole (dogs = 10 mg/kg/day tablets)
How can we treat an environment contaminated with dermatophytosis?
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%)
What are the indications for a skin biopsy?
Neoplasia - suspected or obvious Unusual or serious generalised dermatosis Condition poorly responsive to therapy Other diagnostic tests not helpful Vesicles, bullae, erosions, ulcerations
How do we carry out a skin biopsy?
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
What results can we get from a skin biopsy?
Diagnostic
Compatible with clinical diagnosis
Not compatible with clinical diagnosis
Non-diagnostic
What “flare” factors may start the itch-scratch cycle?
Bacterial and yeast infection
Fleas
Dry skin and low humidity/sweating
Psychological factors (stress, anxiety, boredom?)
Describe the Visual Analog Scale for clinical assessment of pruritus.
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
What are the clinical signs of canine atopic dermatitis?
Associated with self-trauma and secondary bacterial and Malassezia infections - alopecia, erythema, excoriation, hyperpigmentation and lichenification
How can we diagnose canine atopic dermatitis?
By ruling out other conditions that cause pruritus
Intradermal and blood testing used to select allergens for immunotherapy
What are the indications for allergen testing?
DO NOT confirm diagnosis of atopic disease
May identify allergens of clinical significance
Provide basis for allergen-specific immunotherapy (ASIT)/allergy vaccine/desensitisation
What are the clinical signs of pyoderma?
Intraepidermal pustules
Primary and secondary lesions
Annular lesion with peeling epidermal collarette
Antibiotic responsive
Underlying causes = ectoparasitism, allergy, endocrinopathies
Describe pyoderma therapy.
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
How are topical therapies helpful for pyoderma?
Remove crust, scale and exudate from skin surface
Reduce number of bacteria
Promote drainage of deeper lesions
Reduce pain and pruritus
How are topical therapies used to treat pyoderma?
Clip coat
Used 2-3 times weekly until clinical remission
Products usually contain chlorhexidine
Aim for 10 min soak before rinsing thoroughly
What is Malassezia?
Malassezia pachydermatis
Opportunistic yeast pathogen
Normally resident in external ear canal, chin, perioral and interdigital areas
What factors predispose an animal to Malassezia infection?
Alterations in skin microclimate (sebum production, moisture)
Allergic and bacterial skin disease
What are the clinical signs of Malassezia infection?
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
How do we diagnose Malassezia infection?
Impression smears with a dry swab/direct slide contact
Acetate strip preparations
Culture
Serology - not recommended
What therapies are available to treat Malassezia infection?
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
THIS CARD IS A REMINDER TO STUDY ENDO/ECTOPARASITES:)
VN Week 10 - Dermatological Infections and Infestations
