Dermatology Flashcards
Layers of skin
Epidermis
Dermis
Subcutis
Which layer of skin is immunological barrier?
Dermis
Mediator in atopic dermatitis
IgE
Factors contributing to atopic dermatitis
Skin barrier
Immune system (allergy)
Bacteria and yeast
Main bacteria to consider in dysbiosis
Staphylococcus pseudintermedius
Main yeast to consider in dysbiosis
Malassezia pachydermatitis
What type of pyoderma is a ‘hotspot’
Surface pyoderma
Surface pyoderma that affects face folds
Intertrigo
Pathogens more often involved in superficial pyoderma
Staphylococcus
Presentation of superficial pyoderma
Papules
Pustules
(Epidermal collarettes)
(Patchy alopecia in short coat dogs)
Parts of a diff quik stain
Fixative
Eosinophilic
Basophilic
When to use impression smear
Moist lesions on flat skin
Which part of diff quik stain shouldn’t be used on ear wax?
Fixative
Lesions suitable for acetate tape strip
Skin folds, between toes, lip folds
‘Dry’ lesions
How do you stain acetate tape strip?
Diff quik but not fixative
How do you get a cytology sample for a pustule?
Lance and do impression smear
Which type(s) of pyoderma should you use topical therapy for?
Surface and superficial
Which type(s) of pyoderma should you use systemic therapy for?
Deep
Systemic therapy options for infectious skin disease
Anti-inflammatory/anti-pruritic
Antibiotics/antifungals
Supplement with omega oils (skin barrier)
Microbiome probiotics?
Topical therapies available for skin disease
Glucocorticoids/immune modulating
Antibiotics/antifungals
Antiseptics
Topical skin barrier support (ophytrium, ceramides, fatty acids/omega oils)
Topical probiotics?
Type I hypersensitivity
Cross linking of IgE molecules on mast cell wall surface by allergen = degranulation and tissue inflammation
Canine atopic dermatitis
Environmental/food induced
Common chronic, relapsing, pruritic and inflammatory skin syndrome
Type I hypersensitivity/IgE antibodies
Cutaneous reaction patterns of cats
Face, head and neck pruritis
Self induced alopecia
Miliary dermatitis
Eosinophilic granuloma complex (granulomas/ulcers/plaques)
What are the main three allergic conditions in cats
FASS (feline atopic skin syndrome)
FFA (feline food allergy)
FAD (flea allergic dermatitis)
Systematic approach to cat skin condition
Contact irritant dermatitis
Often >1 animal
Nature of substance, not hypersensitivity
Contact hypersensitivity
Type IV reaction
Affects isolated individual
Lesion in area of contact, particularly sparsely haired region
Patch test?
What hypersensitivity causes vasculitis in a vaccine reaction?
Type III
Drug reaction
Can manifest as almost any type of cutaneous lesion or reaction pattern
Any type of hypersensitivity
Variable pruritis
Most commonly antibiotics (potentiated sulphonamides)
Eosinophilic folliculitis/furunculosis
Reaction to presumed arthropod bite
Acute onset, highly pruritic
Established allergy tests (CAD)
Allergen specific IgE serology testing
Intradermal testing
Elimination diet options
Hydrolysed (common protein, convenient, expensive, may still react, use soy not chicken)
Limited antigen (novel protein and carbohydrate, convenient, cheaper)
Home cooked (cheaper?, know ingredients?, client compliance poor, not nutritionally balanced)
Why would you do IgE serology in CAD work up?
Select environmental allergens for allergen-specific immunotherapy
Treatment options for CAD
Glucocorticoids (effective, cheap, anti-pruritic and anti-inflammatory, topical or oral)
Oclacitinib (anti-pruritic, dogs only, oral)
Lokivetmab (block IL-31 = anti-pruritic, dogs only, SC, any age/kidney/liver, can combine with other therapies)
Ciclosporin (anti-inflammatory and anti-pruritic, dogs and cats, expensive, oral, T-cell suppressor so don’t use 2w before/after vaccs. or in cats with FeLV/FIV/toxoplasmosis, slow onset)
Hypothyroidism
Depressed/heat seeking
Epidermis thin, dermis thicker (myxoedema)
Non-pruritic unless secondary bacterial pyoderma/Malassezia
Treatment: thyroid supplementation
Hyperadrenocorticism
Normal demeanor, older dogs
Dilute urine (SG<1.015)
Epidermis thin, dermis thin (see vessels/bruising due to reduced collagen)
Rarely pruritic
Calcinosis cutis/marked skin elasticity
Treatment: Trilostane
Hyperoestrogenism
Uncommon
Bilateral symmetrical alopecia, trunk/ventrum/caudal thighs/neck
Hyperpigmentation
Sexually attractive to males
Severe anaemia/pancytopaenia
Epidermis thin
Linear preputial oedema
Treatment: castration
Cyclic flank alopecia
Common
Bilateral symmetrical alopecia, truncal/clear borders, improves in summer
Biopsy useful
Treatment: melatonin supplementation 2-3m
Alopecia X
Rare
Bilaterally symmetrical alopecia
Disease of elimination (17-OH progesterone/biopsy highly suggestive)
Treatment: castration? Melatonin? Purely cosmetic
Inflammatory causes of alopecia
Infectious agents (bacterial folliculitis, dermatophytosis)
Parasitic (demodicosis, leishmaniasis)
Immune mediated (alopecia areata, dermatomyositis, sebaceous adenitis)
Likely diagnosis
Bacterial folliculitis
(Short coat pyoderma and neutrophils with intracellular bacteria)
Most common species causes dermatophytosis/ringworm
Microsporum canis
Which dermatophytosis species can resemble deep pyoderma clinically?
Trichophyton species
Diagnosis of dermatophytosis
Wood’s lamp
Trichography (arthrospores/’soap bubbles’ surround hair shaft/hyphae within hair)
Dermatophyte test medium in house
External lab fungal culture +/- PCR (gold standard, coat brush/Mackenzie technique)
Biopsy (spores)
Treatment of dermatophytosis
Topical: miconazole shampoo 2-3 times a week
Environmental: isolate, sodium hypochlorite 1:10 (bleach)
Systemic: itraconazole
Meaning of a colour change in fungal culture
Positive
What is the parasite?
Demodex mite (D. canis/injai/catai, short bodied D. gatoi in cat)
Skin commensal (juveile/immune suppression)
Localised to generalised alopecia
Follicular casting/comedones/greasy +/- bacterial infection
Skin scrape/hair pluck
Treatment: flurolaner/afoxolaner until 2-3 negative skin scrapes (Q4w)
Immune mediated alopecia
Sebaceous adenitis (truncal hair, poodle)
Dermatomyositis (face/bony prominences, collies)
Alopecia areata (regrowth of white hair, trichogram: ! mark hairs)
Hair growth phases
Anagen (growth)
Catagen (transition)
Teolgen (resting/falls out)
Hair synthesis defects
Pattern alopecia (Dashchund)
‘Bald thigh syndrome’ (Sighthounds)
Follicular dysplasia (wear points, water spaniel/dog)
Black hair follicle dysplasia (black hairs dull/lost)
Colour dilution alopecia (blue/fawn coats)
Anagen defluxation/effluvium (no whiskers, chemo/severe illness)
Most common cause of crusting in the dog
Superficial pyoderma
Diseases presenting primarily as crusting
Pemphigus foliaceus (pustules, seen as crusting)
Canine juvenile sterile granulomatous dermatitis and lymphadenitis (‘puppy strangles’)
Squamous cell carcinoma/solar dermatitis
Feline acne
Calcinosis cutis
Superficial necrolytic dermatitis
Facial dermatitis of Persians
What is feline acne often secondary to?
Dermatophytosis
Demodicosis
Malassezia
Pyoderma
Furunculosis
Calcinosis cutis
Calcium deposition in skin
Treatment of facial dermatitis in Persians
Ciclosporin +/- prednisolone
(Anti yeast therapy as usually also have Malassezia)
Superficial necrolytic dermatitis (‘hepatocutaneous syndrome’)
Hyperkeratosis of foot pads/crusting
Keratinocyte death due to end-stage liver disease/pancreatic atrophy/glucagonomas
Histopathology, US abdomen, liver biopsy
Dietary supplementation/treat secondary infections
Poor prognosis
Treatment of pemphigus foliaceous
Immunosuppressive systemic glucocorticoids +/- topical, titrated
Sterile granulomatous condition affecting face, pinnae, ears and submandibular lymph nodes of puppy
Juvenile sterile granulomatous dermatitis
(Pyogranulomatous and sterile inflammation, confirm with biopsy, treatment: immunosuppressive prednisolone +/- ciclosporin and topical washes, can scar so treat quickly)
Ectoparasite causing dorsal scale that is zoonotic
Cheyletiellosis
Flea control active in environment and on adult fleas
Imadocloprid and selamectin
Zn-responsive dermatosis
Type I: genetic, husky
Type II: nutritional restriction in rapidly growing dog
Crusted hyperkeratosis on side of face/hocks
Supplement zinc
Ichthyosis of the Golden Retriever
Scale/secondary otitis
Genetic (abnormal cleavage of corneodesmosome)
Symptomatic treatment
Canine ear margin seborrhoea
Relatively uncommon, Dachshunds/hypothyroidism
Adherent keratin on medial a lateral sides of pinna, follicular casts, secondary infection, fissures
Edge resection biopsy
Treatment: incurable, anti-seborrhoeic shampoo, moisturisers, fissures treated with steroids/surgery
Nasodigital hyperkeratosis
Cut off, hydrate keratin, essential fatty acids
Nasal parakeratosis of Labrador retrievers
Do not breed
Topical vitamin E, petroleum jelly and retinoids
Footpad hyperkeratosis of Dogue de Bordeaux
Biopsy/genetic tes
50% propylene glycol soaks, retinoids
Common complication of callus
Deep pyoderma
Idiopathic sebaceous adenitis
Dry scale, hair loss
Biopsy: absent sebaceous glands
Treatment: lubricating shampoo, fatty acid/oil supplementation, ciclosporin
Topical agents for scaling conditions
Sulphur (keratoplastic/lytic, antibacterial/fungal)
Salicylic acid (keratolytic, synergistic with sulphur)
Selenium sulphide (keratoplastic/lytic)
Moiturisers (zinc-gluconate, d-panthemol, lipsomes, glycerin, propylene glycol, urea, vaseline)
Infection in facial fold dermatitis (intertrigo)?
Surface pyoderma
Treatment for CAD that is a calcineurin inhibitor which reduces release of inflammatory mediators
Ciclosporin
Lesion that presents with pruritis
Epidermal collarettes
Most effective treatment for canine demodicosis
Amitraz washes every 5-7 days
(The only canine skin mite for which selamectin is ineffective)
Best flea adulticide for dog with FAD bathed 3 times weekly in mionazole/chlorhexidine shampoo
Spinosad
