Dermatology Test Questions - Canine & Feline Pruritis Flashcards Preview

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Flashcards in Dermatology Test Questions - Canine & Feline Pruritis Deck (64)
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1

What is a papule?

Small solid elevation of skin less than 1 cm in diameter
Larger lesions are called plaques


2

Pustule (pimple)

Small circumscribed elevation of epidermis filled with pus

3

Crust (scab)

Adherence of dried exudate, serum, pus or blood to the skin surface

4

Epidermal collarette (scaly ring)

Peeling keratin arranged in a circle

5

Scale (flake, dandruff)

Cluster of corneocytes, which have retained a large degree of cohesion with one another and detach as such from the surface of the stratum corneum

6

4 goals of a skin biopsy

1. Establishment of a definitive diagnosis
2. Rule out other diseases
3. Prioritize differential diagnoses
4. Predict prognosis

7

Pathogenesis for Canine atopic (allergy) dermatitis (Type of reaction, route of exposure)

-> Older paradigm implied an immunological defect (inside-out theory)
• IgE-mediated, immediate hypersensitivity reaction (type I)
• Cell-mediated, delayed hypersensitivity reaction (type IV)
4 routes of exposure to environmental allergens
1. Percutaneous +++
2. Inhalation
3. Ingestion
4. conjunctival
(More recently, a primary defect in the skin barrier function has been recognized (outside-in theory))

8

Canine atopic dermatitis - typical lesion & distribution (11)

Face Ear pinnae, Front feet
Ventral neck, axillae, inguinae, ventral abdomen, perineum, ventral tail, flexural and medial aspects of extremities

9

Cutaneous adverse food reaction (CAFR) - pathogenesis (Type of reaction, route of exposure)

• Immune-mediated CAFR
IgE-mediated, immediate hypersensitivity reaction (type I)
Type III hypersensitivity reaction (immune-complex deposition)
Cell-mediated, delayed hypersensitivity reaction (type IV) 1
Route of exposure to trophallergen: ingestion
• Non immune-mediated (food intolerance)

10

Cutaneous adverse food reaction (CAFR) - typical lesion & distribution (4)

Face
Ear pinnae
Feet
Perianal area?

11

Cutaneous adverse food reaction (CAFR) - diagnosis

Relies primarily on the patient’s signalment, clinical signs and disease history and not on a laboratory test
Dietary restriction-provocation trial

12

Canine atopic dermatitis - diagnosis (2)

Relies primarily on the patient’s signalment, clinical signs and disease history and not on a laboratory test
Use most recent criteria for diagnosis of CAD (Favrot, 2010)

13

Flea allergy dermatitis - pathogenesis
(Type of reaction, route of exposure)

IgE-mediated, immediate hypersensitivity reaction (type I)
Cell-mediated, delayed hypersensitivity reaction (type IV)
Jones-Mote-type hypersensitivity (JMH, involves basophils)
1 route of exposure to flea salivary allergen: flea bite

14

Flea allergy dermatitis - distribution (3)

Dorso-lumbar area
Base of the tail
Medial and caudal thighs

15

Flea allergy dermatitis - diagnosis (6)

Signalment, clinical signs and disease history
Presence of fleas and/or flea dirt
Flea combing
Intradermal test (flea salivary allergen) Immunoglobulin E serum test (flea salivary allergen)
Parasiticidal therapeutic trial

16

Scabies - pathogenesis (type of reaction, method of infection)

Hypersensitivity reaction causes severe pruritus (sudden onset)
Puppy, kittens, young animals, poor hygiene Immunosuppression in adults
Exposure to wildlife (coyotes, red foxes, grey wolves, bears)
Exposure to other pets (breeding/boarding facilities, groomers, shows)
Contagion to owners (papular rash on forearms, abdomen)
Contagion to other dogs and cats in contact

17

Scabies - typical lesion & distribution (3)

Typical lesion: crust
Margin of the pinnae
Hock
Elbow

18

Scabies - diagnosis (4)

Positive pinnal-pedal reflex (Sensitivity 82%, specificity 94%, uncommon false positives: canine atopic dermatitis, otitis)
Positive superficial skin scrapings (parasites will NOT be found in 50-80-% of case, recovery of Sarcoptes eggs or fecal pellets is diagnostic)
Immunoglobulin G serum test (sensitivity 92%, specificity 96%, not available in Canada)
Parasiticidal therapeutic trial (« scabies incognito »)

19

Cheletielliosis - epidemiology

(mites) Puppies, kittens, young animals, poor hygiene
Immunosuppression in adults
Contagious
Potentually zoonotic

20

Cheletielliosis - typical lesion & distribution (1)

Typical lesion: scale
Dorsum

21

Cheletielliosis - diagnosis (3)

Superficial skin scraping
Acetate tape preparation
Parasiticidal therapeutic trial

22

Favrot`s criteria for CAD diagnosis (Canine Atopic Dermatitis)

Combination of any 5/8 criteria:
1. Onset of clinical signs under 3 years of age (>< food allergy, at any age)
2. Dog living mostly indoors
3. Glucocorticoid-responsive pruritus
4. Alesional pruritus at onset (pruritus without macroscopically visible clinical lesions)
5. Affected front feet
6. Affected ear pinnae
7. Non-affected ear margins (>< scabies)
8. Non-affected dorso-lumbar area (>< flea allergy dermatitis)

23

Miliary Dermatitis - description

(pattern) Small crusts, papules and erosions
Miliary means "like millet seeds"
Often localized to dorso-lumbar area and pre-aural region
May be generalized

24

Miliary Dermatitis - Differential diagnosis (5)

Allergy (flea allergy dermatitis (FAD) > feline atopic dermatitis, cutaneous adverse food reaction CAFR)
Ectoparasitic infestation
Dermatophytosis
Adverse drug reaction (face and head, methimazole, propanolol)
Idiopathic

25

Miliary Dermatitis - Diagnosis (8)

Skin scraping
Acetate tape preparation
Flea combing
Wood's lamp examination
Dermatophyte culture
Parasiticidal therapeutic trial
Dietary restriction-provocation trial Intradermal test, immunoglobulin E serum test

26

Symmetrical Alopecia - Description

Bilaterally symmetrical alopecia
Often localized to dorso-lumbar area and ventral abdomen, but can also affect limbs and flanks
Head and neck spared
Non-inflammatory (no other skin lesions)

27

Symmetrical Alopecia - Differentials (5)

Allergy (CAFR (Cutaneous adverse food reaction) > feline atopic dermatitis, FAD) Ectoparasitic infestation (e.g. Fleas)
Dermatophytosis
Psychogenic (psychological origin)
Paraneoplastic Endocrinopathy (rare) Idiopathic

28

Symmetrical Alopecia - Diagnosis (9 ways to help achieve)

Skin scraping
Acetate tape preparation
Flea combing
Wood`s lamp examination
Dermatophyte culture
Parasiticidal therapeutic trial
Dietary restriction-provocation trial
Intradermal test, immunoglobulin E serum test Dermatohistopathology (lack of dermal inflammation is not a good indicator of psychogenic alopecia)

29

Eosinophilic Dermatoses - General Information/Using the term

Avoid using the name `Eosinophilic granuloma complex` clinically and histopathologically as it is an inconsitent mixture of clinical and histopathological terms
The 2 different forms of this cutaneous pattern: (1. Papule/ plaque / nodule / edema 2. Ulcer)
Have the same underlying causes
Have a common histoptahological feature: an eosinophilic cell infiltrate in the dermis
Can be observed in the same cat concurrently

30

Eosinophilic Dermatoses - Description (2 parts)

1. Papule/ plaque / nodule / edema
Variable pruritus and pain
Papules or coalescing, firm, flat-topped erythematous and moist plaques, often localized to the ventral abdomen
Linear, vertical and firm lesions seen on caudal thighs, more rarely on the neck, lateral thorax and thoracic limbs
Firm nodule found in oral cavity (tongue, palate). May become ulcerated. May cause halitosis, partial anorexia, dysphagia and ptyalism
Pododermatitis with ulcerated or edematous footpads and interdigital erythema
Edema of lower lip or chin
2. Indolent ulcer
Non-pruritic and painless
Usually located on midline of upper lip or adjacent to canine upper teeth. May affect philtrum (between nose & upper lip)
Often unilateral, sometimes bilateral
Size varies from 2 mm - 5 cm, enlarges progressively