Approach to Scale

Question 1

What is scale?

Answer 1

Desquamated corneocytes on skin and in hair coat

Question 2

What may increased scaling result from?

Answer 2

• Abnormal desquamation (shedding of corneocytes)
• Abnormal cornification (creation of the outer cornified layer of epithelium)
• Inflammation (increased keratinocyte turnover)
• Bacterial and fungal enzymatic action

Question 3

What is primary scaling?

Answer 3

Scaling as a direct result from disease pathology

Question 4

What is secondary scaling?

Answer 4

Scaling due to skin inflammation, internal disease or external factors
*More common

Question 5

How is secondary scaling managed?

Answer 5

*Treat primary disease - e.g. hypothyroidism
*Manage by removing excess scale - baths w moisturisers

Question 6

What are the differential diagnoses from primary scaling?

Answer 6

*Feline acne
*Canine ear margin seborrhea
*Primary seborrhea
*Ichthyosis
*Zinc responsive dermatosis
*Vitamin A-responsive dermatosis

Question 7

What are the most common differential diagnoses from secondary scaling?

Answer 7

*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

Question 8

If pruritus present with scaling what is the most likely causes?

Answer 8

*Parasites
*Bacterial infection
*Allergic skin disease

Question 9

What are the 2 different syndromes of zinc-responsive dermatosis?

Answer 9

• 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)

Question 10

What dog breeds are predisposed to type 1 + type 2 zinc responsive dermatosis?

Answer 10

Type 1 = Siberian huskies, Alaskan malamutes, English bull terriers
Type 2 = Great dane, GSD, Labrador Usually young giant breeds

Question 11

What is the lesion distribution of zinc responsive dermatosis?

Answer 11

• Periocular, perioral, chin, ears, occasionally genitals
• May see hyperkeratotic footpads
• Sites of trauma (Zn required for normal
  keratinisation)

Question 12

How is zinc responsive dermatoisis diagnosed?

Answer 12

Skin biopsy - parakeratosis = key finding

Question 13

What is the treatment of zinc responsive dermatosis?

Answer 13

*Type 1 = Zn supplementation + prednisolone (Increase Zn absorption)
*Type 2 = correct diet

Question 14

What is the pathogenesis of Ichthyosis of Golden retrievers?

Answer 14

• Genetic: mutation in PNPLA1-gene
• Leads to abnormal cleavage of desmosomes between corneocytes during desquamation

Question 15

How is Ichthyosis diagnosed?

Answer 15

• 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

Question 16

What is the treatment of Ichthyosis?

Answer 16

*Scaling = cosmetic disease = symptomatic treatment only

Question 17

What animals are affected by ear margin seborrhoea?

Answer 17

• Mainly adult onset, but can occur in puppies
• Marked breed predilection in Dachshunds
• Non-pruritic

Question 18

How is ear margin seborrhoea diagnosed?

Answer 18

Skin biopsy
-rule out parasites

Question 19

How is ear margin seborrhoea treated?

Answer 19

• Emollient rinses, Vaseline, propylene glycol
• Surgery to remove pinnal margin (rarely required!)

Question 20

What is the history of thymoma-induced exfoliative dermatitis?

Answer 20

• Middle to older age
• Non-pruritic
• +/- signs of respiratory compromise (due to thymoma in thorax)

Question 21

How is thymoma-induced exfoliative dermatitis diagnosed?

Answer 21

*Skin biopsy
*Thoracic radiography / CT

Question 22

What is the treatment of thymoma-induced exfoliative dermatitis?

Answer 22

*Surgery to remove thymoma
*Immunomodulatory drugs - prednisolone + ciclosporin

Question 23

What animals does idiopathic facial dermatitis usually affect? What is the distribution of the lesions?

Answer 23

Persian cats
* Distribution: periocular skin, nasal folds, muzzle, chin

Question 24

How is idiopathic facial dermatitis treated?

Answer 24

• Anti-yeast therapy
• Keratolytic shampoos
• Immunomodulation: ciclosporin, prednisolone, topical tacrolimus

Question 25

Where is feline acne most commonly seen?

Answer 25

Chin (sometimes lips)

Question 26

How is feline acne diagnosed?

Answer 26

• Largely clinical diagnosis: rule out Demodex cati
• Cytology: Malassezia overgrowth

Question 27

How is feline acne treated?

Answer 27

• Topical antiseptics +/- antimicrobials
• Topical keratinolytics
• Prednislone if significant inflammation present

Question 28

What are some non-specific symptomatic treatments for scaling?

Answer 28

*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