Approach to Scale Flashcards
What is scale?
Desquamated corneocytes on skin and in hair coat
What may increased scaling result from?
- Abnormal desquamation (shedding of corneocytes)
- Abnormal cornification (creation of the outer cornified layer of epithelium)
- Inflammation (increased keratinocyte turnover)
- Bacterial and fungal enzymatic action
What is primary scaling?
Scaling as a direct result from disease pathology
What is secondary scaling?
Scaling due to skin inflammation, internal disease or external factors
*More common
How is secondary scaling managed?
*Treat primary disease - e.g. hypothyroidism
*Manage by removing excess scale - baths w moisturisers
What are the differential diagnoses from primary scaling?
*Feline acne
*Canine ear margin seborrhea
*Primary seborrhea
*Ichthyosis
*Zinc responsive dermatosis
*Vitamin A-responsive dermatosis
What are the most common differential diagnoses from secondary scaling?
*Inflammation (allergy, parasites, bacterial infection, dermatophytosis) and
almost any resolving inflammatory dermatosis
*Endocrinopathies (hypothyroidism and HAC)
*Diabetes mellitus
*Callus (compact adherent scale)
*Idiopathic facial dermatitis of cats (‘dirty face’ in Persian cats)
*Epitheliotropic lymphoma
*Sebaceous adenitis
If pruritus present with scaling what is the most likely causes?
*Parasites
*Bacterial infection
*Allergic skin disease
What are the 2 different syndromes of zinc-responsive dermatosis?
- Type I: genetically-induced defective intestinal absorption of Zn
- Type II: rapidly growing dogs fed a Zn deficient diet (or over-supplemented with
substances that interfere with Zn absorption)
What dog breeds are predisposed to type 1 + type 2 zinc responsive dermatosis?
Type 1 = Siberian huskies, Alaskan malamutes, English bull terriers
Type 2 = Great dane, GSD, Labrador Usually young giant breeds
What is the lesion distribution of zinc responsive dermatosis?
- Periocular, perioral, chin, ears, occasionally genitals
- May see hyperkeratotic footpads
- Sites of trauma (Zn required for normal
keratinisation)
How is zinc responsive dermatoisis diagnosed?
Skin biopsy - parakeratosis = key finding
What is the treatment of zinc responsive dermatosis?
*Type 1 = Zn supplementation + prednisolone (Increase Zn absorption)
*Type 2 = correct diet
What is the pathogenesis of Ichthyosis of Golden retrievers?
- Genetic: mutation in PNPLA1-gene
- Leads to abnormal cleavage of desmosomes between corneocytes during desquamation
How is Ichthyosis diagnosed?
- Rule out parasites (unlikely as non-pruritic)
- Skin biopsy
- Genetic testing widely available - if several puppies in litter affected consider skipping biopsy and performing genetic testing
What is the treatment of Ichthyosis?
*Scaling = cosmetic disease = symptomatic treatment only
What animals are affected by ear margin seborrhoea?
- Mainly adult onset, but can occur in puppies
- Marked breed predilection in Dachshunds
- Non-pruritic
How is ear margin seborrhoea diagnosed?
Skin biopsy
-rule out parasites
How is ear margin seborrhoea treated?
- Emollient rinses, Vaseline, propylene glycol
- Surgery to remove pinnal margin (rarely required!)
What is the history of thymoma-induced exfoliative dermatitis?
- Middle to older age
- Non-pruritic
- +/- signs of respiratory compromise (due to thymoma in thorax)
How is thymoma-induced exfoliative dermatitis diagnosed?
*Skin biopsy
*Thoracic radiography / CT
What is the treatment of thymoma-induced exfoliative dermatitis?
*Surgery to remove thymoma
*Immunomodulatory drugs - prednisolone + ciclosporin
What animals does idiopathic facial dermatitis usually affect? What is the distribution of the lesions?
Persian cats
* Distribution: periocular skin, nasal folds, muzzle, chin
How is idiopathic facial dermatitis treated?
- Anti-yeast therapy
- Keratolytic shampoos
- Immunomodulation: ciclosporin, prednisolone, topical tacrolimus
Where is feline acne most commonly seen?
Chin (sometimes lips)
How is feline acne diagnosed?
- Largely clinical diagnosis: rule out Demodex cati
- Cytology: Malassezia overgrowth
How is feline acne treated?
- Topical antiseptics +/- antimicrobials
- Topical keratinolytics
- Prednislone if significant inflammation present
What are some non-specific symptomatic treatments for scaling?
*Keratoplastic / keratolytic products
* These reduce scale production
(keratoplastic) e.g. sulphur and coal
tar shampoos or remove scale e.g.
salicylic acid shampoos
*Moisturizing and emollient products
* These reduce transepidermal water
loss and prevent inflammation e.g.
products containing oils, propylene
glycol and urea
