Derm - Crusting, ulceration, erosions, scale

Question 1

What are the causes of ulceration?

Answer 1

Trauma
Mechanical injuries
Acute moist dermatitis
Skin fold pyoderma
Thermal injuries
Chemical injuries
Radiation
Neoplasia
Infectious agenst

Question 2

What is the prevalence of immune mediated skin disease?

Answer 2

Uncommon to rare

Question 3

What are the causes of immune mediated skin disease?

Answer 3

Drugs
Neoplasia
Systemic disease
Other immune mechanisms

Question 4

What should you consider when diagnosing immune mediated skin disease?

Answer 4

‘Interface dermatitis’ is not definitive
Consider underlying causes

Question 5

How do you treat immune mediated skin disease?

Answer 5

Immunosupressive drugs

Question 6

What is the prognosis of immune mediated skin disease?

Answer 6

Poor - Adverse effects of therapy, disease difficult to manage/treat

Question 7

What are the attachments between epidermal basal cells called?

Answer 7

Desmosomes

Question 8

What are the attachments between the basal cells and the lamina lucida called in the skin?

Answer 8

Hemidesmosomes

Question 9

What disease attacks the desmosomes?

Answer 9

Pemphigus - immune system attacks the desmosome attachments

Question 10

What dogs are affected with canine pemphigus foliaceus?

Answer 10

Any breed and any age of onset - most likely 2 to 7 years

Question 11

What are the clinical signs of canine pemphigus foliaceus?

Answer 11

Chronic disease
Generalised skin lesions - face, pinnae, footpads, trunk
Cause pruritus

Question 12

What lesions does canine pemphigus foliaceus cause?

Answer 12

Vesicles and pustules - rupture to form crusts and erosions
Scaling and alopecia

Question 13

How do you diagnose canine pemphigus foliaceus?

Answer 13

Cytology of pustules
Skin biopsy using punch tool

Question 14

What is found on cytology in canine pemphigus foliaceus?

Answer 14

Keratinocytes, neutrophils, sometimes eosinophils
No cocci - sterile pustules
However can get secondary infection so need to treat this before testing

Question 15

What is the appearance of canine pemphigus foliaceus on histopath?

Answer 15

Intraepidermal and intrafollicular pustules with acantholytic keratinocytes in the granular or upper spinous cell layers

Question 16

What is the most common autoimmune skin condition in cats?

Answer 16

Feline pemphigus foliaceus - not as common as in dogs tho

Question 17

What are the clinical signs of feline pemphigus foliaceus?

Answer 17

Lesions on head, ears and nose, extending to rest of body
Claw beds have thick caseous green purulent discharge

Question 18

What is a differential diagnosis of feline pemphigus foliaceus and how do you differentiate them?

Answer 18

Dermatophytosis - do a fungal culture which will come back negative

Question 19

How do you diagnose feline pemphigus foliaceus?

Answer 19

Cytology of pustule - neutrophils with acantholytic keratinocytes
Skin biopsy for histopathology
Haematology - eosinophilia

Question 20

How do you treat pemphigus?

Answer 20

Glucocorticoids - prednisolone - 2mg/kg/day until remission, then slowly reduce dose

Question 21

What is the second most common autoimmune skin disease in dogs?

Answer 21

Canine discoid lupus erythematosus (facial DLE)

Question 22

What are the clinical signs of facial DLE?

Answer 22

Photosensitive dermatosis of the top of the nose causing
Hypopigmentation
Erythema, scaling, erosions, ulcerations
Loss of normal architecture

Question 23

What is the appearance of facial DLE on histopath?

Answer 23

Lichenoid lymphoplasmacytic interface pattern

Question 24

How do you treat facial DLE?

Answer 24

Topical glucocorticoids
Topical tacrolimus - cyclosporin drug
UV protection - suncream
Vitamin E

Question 25

What is an autoimmune skin condition/sydrome that affects horses?

Answer 25

Ulcerative pastern dermatitis

Question 26

What are the clinical features of ulcerative pastern dermatitis?

Answer 26

Cellulitis, ulceration, crusting and oedema on the hind pasterns Fissures Excessive granulation tissue Lameness

Question 27

What are some contagious causes ulcerative pastern dermatitis?

Answer 27

Staph, dermatophilosis Chorioptes Dermatophytosis

Question 28

What are some non contagious causes of ulcerative pastern dermatitis?

Answer 28

Photosensitisation Vasculitis Chronic progressive lymphoedema

Question 29

How do you treat ulcerative pastern dermatitis?

Answer 29

Clip area - sedate Medicated chlorhexidine shampoo Analgesia

Question 30

When do horses get alopecia?

Answer 30

Secondary to pruritus or folliculitis

Question 31

What can cause equine pruritus?

Answer 31

Infectious causes - staph aureus Parasites - flies, mites Allergy Photosensitisation Contact reaction

Question 32

What are the clinical signs of lice in horses?

Answer 32

Alopecia Pruritus Scale

Question 33

How do you diagnose lice in horses?

Answer 33

They are visible to the naked eye - put rug on so warm, then remove and look

Question 34

What are the different types of scale?

Answer 34

Most are dry, powdery, flaky keratin fragments Some are waxy, greasy with a rancid odour

Question 35

Disorder of what process is involved in scale formation?

Answer 35

Cornification

Question 36

What are the steps of cornification?

Answer 36

Bundling of the keratin Replacement of the cell membrane with a cornified envelope Formation of lipid lamellar bilayers Desquamation (exfoliation)

Question 37

What does the cornified envelope do?

Answer 37

Makes the corneocytes resistant to being broken down

Question 38

What is filaggrin?

Answer 38

Filaggrin aggregating protein - helps to aggregate the keratin filaments within the corneocyte

Question 39

What enzyme helps to mediate the aggregation of keratin filaments?

Answer 39

Transglutaminase

Question 40

What are in the stratum corneum?

Answer 40

A lipid rich matrix full of cells Lamellar bodies containing lipid substrate

Question 41

What are epidermal lipids derived from?

Answer 41

Keratinocytes and sebaceous glands

Question 42

What can cause scale formation?

Answer 42

Abnormalities in epidermal cell turnover or keratin synthesis

Question 43

What are primary keratinisation disorders? How common are they?

Answer 43

Breed related congenital diseases Uncommon to rare

Question 44

What are secondary/acquired keratinisation disorders?

Answer 44

Due to another underlying cause such as parasites, allergy, endocrinopathies etc. Lot more common

Question 45

What are some examples of primary keratinisation defects

Answer 45

Sebaceous adenitis Idiopathic nasodigital hyperkeratosis Lethal acrodermatitis

Question 46

What is sebaceous adenitis?

Answer 46

When inflammatory infiltrate target sebaceous glands causing scaling

Question 47

What is idiopathic nasodigital hyperkeratosis?

Answer 47

Excess keratinisation of the ears and pads of older dogs

Question 48

What is lethal acrodermatitis?

Answer 48

A very rare bad disease affecting English bull terries fact, distal limbs and feet

Question 49

What is ichthyosis?

Answer 49

A rare congenital disease causing large adhered flakes of scale on dogs (fish scale)

Question 50

What breeds does ichthyosis affect?

Answer 50

Golden retrievers, jack russell terriers, american bulldogs

Question 51

What causes ichthyosis?

Answer 51

Defects in the formation of the stratum corneum - increased stratum corneum production and decreased corneocytes desquamation - retention hyperkeratosis

Question 52

What are the two types of ichthyosis?

Answer 52

Epidermolytic - suprabasal keratinocyte vacuolation due to mutation in epidermal keratins Non epidermolytic - transglutaminase mutations and others

Question 53

What is epidermolytic ichthyosis?

Answer 53

When the suprabasal keratinocytes become vacuolated due to mutations in the epidermal keratins

Question 54

What are some examples of scale formation secondary to a defined underlying cause?

Answer 54

Inflammation Allergy Endocrine imbalances Nutritional factors

Question 55

What nutritional factors can cause scale formation?

Answer 55

Zinc

Question 56

What are the two types of zinc nutritional disorders?

Answer 56

Type 1 - adult dogs eg. husky, malamute, samoyed that are unable to absorb zinc Type 2 - Young growing large breed dogs that are growing too fast and not getting enough zinc in their diet

Question 57

What are the clinical signs of zinc responsive dermatosis type 1?

Answer 57

Scaling, crusting, erythema and alopecia Can be pruritic

Question 58

Where does zinc responsive dermatosis type 1 affect?

Answer 58

Around the eyes, on the nose, ears and muzzle and around the mouth On foot pads

Question 59

How do you diagnose zinc responsive dermatosis type 1?

Answer 59

On clinical signs and seeing parakeratotic hyperkeratosis (have nuclei)

Question 60

What animals can get zinc deficiencies?

Answer 60

Dogs - breeds or growing pups Goats Alpacas

Question 61

What is a common sign of zinc deficiencies in goats and alpacas?

Answer 61

Scaling

Question 62

How do you manage scaling disorders?

Answer 62

Address the underlying cause Treat secondary microbial infections Topical therapy

Question 63

What topical therapy can you use on scaling disorders?

Answer 63

Medicines that slow down the production of corneocytes eg. salycyclic acid, a-hydroxyacids, glycerine