23.11.1: Microbial skin disease

Question 1

Microbial infections causing pruritus

Answer 1

• Bacterial pyoderma (may be surface or pyoderma)
• Malassezia dermatitis
• Dermatophytosis - variably pruritic

Question 2

True/false: both bacterial pyoderma and Malassezia dermatitis are common primary problems in the dog.

Answer 2

False
Both are common but they are very rarely a primary problem.

Question 3

Why should you treat bacterial pyoderma/malassezia dermaitis?

Answer 3

• Improve patient comfort
• Improve skin lesions
• Allow better evaluation of underlying cause -> essential to prevent recurrence

Question 4

True/false: Staphylococci and Malassezia spp are not part of the resident skin flora and are always pathogenic.

Answer 4

False
These organisms can be residents but also opportunistic pathogens.

Question 5

What is the most commonly implicated organism in bacterial pyoderma of dogs? How does this differ in cats?

Answer 5

• S. pseudintermedius is the commonest cause of bacterial pyoderma in both dogs and cats.

Question 6

Differentiate between surface and superficial pyoderma

Answer 6

• Surface pyoderma: bacteria proliferate on epidermal surface.
• Superficial pyoderma: bacteria invade epidermis.

Question 7

What forms of surface pyoderma are there?

Answer 7

• Intertrigo (skin fold infection)
• Acute moist dermatitis, pyotraumatic dermatitis (‘hot spots’)
• Bacterial overgrowth syndrome
• Mucocutaneous pyoderma

Question 8

What forms of superficial pyoderma are there?

Answer 8

• Folliculitis
• Impetigo
• Exfoliative superficial pyoderma

Question 9

Answer 9

Surface pyoderma

Question 10

Answer 10

Folliculitis

Question 11

Answer 11

Impetigo

Question 12

Answer 12

Exfoliative superficial pyoderma

Question 13

What is canine intertrigo and where is it most commonly found?

Answer 13

• Skin fold infection
• Occurs in moist, warm environment of skin folds e.g. facial and tail folds, vulval folds, intertrigenous (skin-skin frictional) areas e.g. of obese animals

Question 14

Answer 14

Canine intertrigo

Question 15

What is acute moist dermatitis and why does it occur?

Answer 15

• a.k.a. pyotraumatic dermatitis, ‘hotspots’
• Acute lesions caused by skin self-trauma
• Triggered by any irritant (flea bite, classically)
• There is very rapid development of bacterial overgrowth -> can progress to pyotraumatic folliculitis if not addressed rapidly

Question 16

This is acute moist dermatitis (pyotraumatic dermatitis). How would you address it and stop it developing into pyotraumatic folliculitis?

Answer 16

• Stop pruritus
• Cleanse and dry skin

Question 17

What are the characteristics of bacterial overgrowth syndrome?

Answer 17

• Bacterial multiplication with no/minimal inflammation on cytology (therefore perhaps not a true pyoderma)
• Often highly pruritic
• Usually involves staphylcocci
• Lesions may be greasy, malodorous, erythematous, alopecia -> hyperpigmentation, lichenification

Question 18

True/false: pyoderma is a differential for any of the 4 feline cutaneous reaction patterns, and focal/multifocal alopecia.

Answer 18

True

Question 19

Answer 19

Mucocutaneous pyoderma

Question 20

What lesions are shown here and what disease could they be suggestive of?

Answer 20

Pustules -> could indicate bacterial pyoderma

Question 21

Answer 21

Patchy alopecia associated with short coat pyoderma

Question 22

Lesion and possible cause

Answer 22

Epidermal collarette -> bacterial folliculitis associated with superficial pyoderma

Question 23

Lesion and condition

Answer 23

Epidermal collarette -> exfoliative superficial pyoderma (ESP)

Question 24

Answer 24

Bullous impetigo
Associated with immature immune system/ immunosuppression

Question 25

Answer 25

Miliary dermatitis

Question 26

Answer 26

Feline acne

Question 27

Answer 27

Satellite lesions seen in a case of acute moist dermatitis (pyotraumatic dermatitis, a surface pyoderma)

The satellite lesions suggest infection may be deeper (pyotraumatc folliculitis/ furunculosis) so need to avoid corticosteroids!

Question 28

Answer 28

Malassezia dermatitis

Question 29

Answer 29

Malassezia dermatitis