Define scale
An accumulation of loose cornified fragments of the stratum corneum
Define crust
Presence of dried exudate on the skin surface
What is follicular casting?
Thickened stratum corneum around hair shaft
What is the most common cause of follicular casting?
Demodecosis
What is a comedo?
Sebaceous gland filled with keratinised debris
What can cause comedomes?
Demodecosis, endocrine disease or as a primary defect of cornification
What is seborrhoea?
Flow of sebum
Vague clinical term for scaling/greasy exudation
What is seborrhoea sicca?
Dry scaling
What is seborrhoea oleosa?
Oily scaling
What is seborrhoeic dermatitis?
Greasy, inflamed skin
What do defects of cornification refer to?
Skin diseases where scaling/follicular casting is a dominant clinical feature
What are some causes of secondary defects of cornification?
Parasites, infection, nutrition, allergy, neoplasia
What are some primary causes of defects of cornification?
Idiopathic or genetic defect
What is spaniel seborrhoea?
Primary defect affecting Cocker Spaniels resulting in increased mitotic rate/decreased turnover time
What do skin grafts of animals with spaniel seborrhoea do?
Remain hyperproliferative resulting in localised or generalised scaling/casting
How is spaniel seborrhoea diagnosed?
Exclude primary causes and biopsy
What is the treatment for spaniel seborrhoea?
Shampoo 2x a week to remove excess scale
Vitamin A (there is a vit A responsive form)
Retinoids (synthetic vit A derivatives) - caution highly teratogenic
What is sebaceous adenitis?
Sebaceous glands are destroyed causing generalised scaling/casting and varying alopecia as it can interfere with normal hair growth
How is sebaceous adenitis diagnosed?
Exclude secondary causes and biopsy
What is the treatment for sebaceous adenitis?
Shampoo, EFA (fatty acids), cyA (cyclosporine not licensed but considered under cascade)
Can use retinoids but teratogenic
What is crusting a consequence of?
Epidermal inflammation due to a severe oedematous response or marker cellular recruitment
What are common triggers of crusting?
Physical damage, infection or infestation
What are the differential diagnoses for pruritic, steroid-resistant crusting lesions?
Scabies, pemphigus, dermatophytosis, cutaneous lymphoma
What is the diagnostic plan for pruritic, steroid-resistant crusting lesions?
Skin scrapings
What is the treatment for scabies?
Amitraz weekly for 6 weeks, body clip if long haired, prednisolone 0.75mg/kg SID for 10 days, cephalexin 20mg/kg BID for 3 weeks
Why can topical drug treatments fail?
Doesn’t reach skin of long haired dogs
Washed off before it can be absorbed in sufficient conc.
What are the DDx for dogs with lameness, lethargy, inappetance, PU/PD, weight loss, progressive skin disease and interdigital dermatitis?
Superficial necrolytic dermatitis, pemphigous foliaceus, systemic lupus erythematosus, drug eruption, erythema multiforme
What are the synonyms for superficial necrolytic dermatitis?
Diabetic dermatosis, hepatocutaneous syndrome, metabolic epidermal necrosis, necrolytic migratory erythema
What is superficial necrolytic dermatitis?
Uncommon erosive, crusting, ulcerative disease which commonly affects the footpads, extremities and periorificial skin of middle-aged and old dogs
How is superficial necrolytic dermatitis (SND) diagnosed?
Rule out parasites
Haematology and biochemistry
Skin biopsy - pallor (oedema, hydropic degeneration) of upper epidermis, ortho/parakeratotic hyperkeratiosis, superficial dermal infiltration (mononuclear cells)
Ultrasound = diffuse hypoechogenic areas in liver
What is the pathogenesis of SND?
Seen with hepatic disease or pancreatic glucogonoma
Bile acids and ultrasound may help differentiation of underlying disease
What is the prognosis of SND?
Poor