Veterinary Dermatology - History And Physical Exam

Front 1

ELEMENTS OF THE PHYSICAL EXAM

Back 1

- Good lighting
- Symmetry
- Distribution of lesions
- Configuration of lesions
- What ARE the lesions

Front 2

DESCRIPTION OF SKIN LESIONS

Back 2

- Type
- Distribution
- Configuration
- Arrangement
- Quality
- Consistency
- Depth

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PRIMARY SKIN LESIONS

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- Macule or patch
- Papule or plaque
- Nodule or tumor
- Pustule
- Vesicle or bulla
- Wheal
- Cyst

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MACULE

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- Well circumscribed, flat area of color change less than or equal to 1cm in diameter
- Increase or decrease in diameter

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PATCH

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- A large macule (greater than 1cm in diameter)

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PAPULE

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- Well circumscribed
- Solid (due to increased cells)
- Usually red elevation in the skin
- Less than 1cm color
- May be SQ
- Follicular: infection
- Non-follicular: allergy
- Any

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PLAQUE

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- Like a large papule
- Greater than 1 cm
- Flat-topped
- Looks like hives but does not pit with pressure

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NODULE

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- Well circumscribed large papule or SQ mass
- Solid
- Elevated
- Greater than 1cm - too big to be acne(bacterial)
- May or may not be ulcerated
- Alopecia or discolored

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TUMOR

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- Vague term
- Nodule size and up

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PUSTULE

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- Like a papule but filled with pus (usually yellowish)
- Like a zit
- Hallmark of bacterial infection (pyoderma)

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WHEAL

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- Primary lesion
- Well circumsized, elevated, flat top
- Evanescent, straight walled
- Contains edema fluid
- Fluid distributed throughout tissue and therefor cannot be liverated by cutting into lesion

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VESICLE

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- Primary lesion
- Like a papule but filled with clear fluid, or anything else but pus

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BULLA

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- Primary lesion
- Blister, filled with fluid that's not pus
- Important to culture.
- Pemphicus: autoimmune

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SCALE

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- Primary or Secondary Lesion
- Flake. Accumulations of loose fragments of the horny layer (stratum corneum)
- Increased epidermal maturation and turnover time

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HYPERKERATOSIS

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- Primary or Secondary Lesion
- Thickened, adherent horny layer
- Increased or altered epidermal maturation or turnover time

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CRUST

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- Secondary Lesion
- Scab. Dried consolidations on skin (exudates, blood, serum, blood, pus, scales, medication)
- Thicker and more tightly adherent than a scale

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SCAR

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- Secondary Lesion
- Area of fibrous tissue replacing damaged dermis and/or subcitis. Usually atrophic or depigmented. In horse, may be proliferative.

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EROSION

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- Secondary Lesion
- Loss of epidermis down to basement membrane
- No scar

Front 19

EXCORIATION

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- Secondary Lesion
- Erosions and ulcers due to self-inflicted trauma (like pruritic disease)

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LICHINIFICATION

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- Secondary Lesion
- Thickened, hardened skin with exaggerated markings
- Hallmark of chronic inflammation

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ULCER

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- Secondary Lesion
- Loss of tissue below basement membrane
- May scar

Front 22

FISSURE

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- Secondary
- Crack in skin secondary to loss of tone associated with inflammation

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COMEDONE

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- Primary or Secondary
- Follicular plugging with excessive keratosebaceous material
- Blackhead

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PIGMENTARY DISTURBANCE - HYPERPIGMENTATION (MELANOSIS) HYPOPIGMENTATION (HYPOMELANOSIS)

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- Secondary
HYPERPIGMENTATION
- Affecting skin (melanoderma)
- Hair (melanotrichia)
- Both - especially chronic inflammation or endocrinopathy

HYPOPIGMENTATION
- Affecting skin (leukoderma, achromoderma)
- Affecting hair (Leukotrichia, achromotrichia)

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ALOPECIA

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- Primary or secondary
- Complete loss of hair from where normally present
- Hypotrichiosis: less than normal
- Inflammatory, endocrine, developmental

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EPIDERMAL COLLARETTE

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- Secondary
- Circular rim of peeling epidermis surrounding a recent erosion or ulcer ("footprint" of prior pustule, vesicle, bulla)

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CHANGES IN ELASTICITY, EXTENSIBILITY

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- Loss of elasticity (hypotonia): associated with hyperglucocorticoidism, hyposomatotropism, catabolic states, senility
- Hyperelastic or hyperextensibility: associated with developmental defects

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CHANGES IN THICKNESS OF SKIN

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- Thin skin assc with hyperglucocorticoidism, hyposomatotropism, catabolic states, senility
- Thick skin assc with chronic inflammation, edema, hypothyroidism (mucinosis) and acromegaly

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QUALITY OF HAIR COAT

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- Secondary
- Dry, dull, brittle, easy epilation common to many inflammatory and hormonal dermatoses

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HYPERHIDROSIS

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- Excessive sweating assc with many inflammatory dermatoses
- Esp canine atopy

Front 31

NIKOLSKY SIGN

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- Secondary
- Normal appearing skin is dislodged with lateral digital pressure
- Like pemphigus and toxic epidermal necrolysis

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SKIN SCRAPING

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- Simple, inexpensive
- Definitive diagnosis of mites, fungi and helminths
- False negatives!
- Superficial: yeast, some ectoparasites
- Deep: Most ectoparasites
- Scrape at periphery of lesion with folding skin, deep enough to draw blood

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SMEARS

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- In combo with special stains, by direct impression or aspiration
- Neoplasms
- Infections
- Autoimmune disorders

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TRICHOGRAPHY

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- Best method!
- Hairs are plucked
- Aligned in mineral oil
- Examined microscopically for evidence of infection, shaft defects, growth stage, and external trauma

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WOODS LIGHT

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- Ultraviolet source
- Positive diagnosis, yellow-green fluorescence of hairs down to level of epidermis and below
- Microsporum canis, M. audouinii, M. distortum
- Only 50% in cats and 30% in dogs will fluoresce
- Worthless in large animals
- Lamp must warm up

Front 36

KOH PREPARATION

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- Skin scrapings and plucked hairs cleared with 10% KOH
- Mainly for dermatophytosis
- Still only 60% accurate

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FUNGAL CULTURE

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- Skin scrapings and plucked hairs
- Place on fungal media
- Most accurate for dermatophyte infections
- Sample untreated lesions only
- Sabouraud best

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BACTERIAL CULTURE AND SENSITIVITY TESTING

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- Fraught with hazards
- Any moist lesions over 24 hours will produce coag+ staph and/or B-hemolytic strep
- Diff-quick results more reliable

Front 39

SCOTCH TAPE PREPARATION

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- Great for surface living parasites
- Not great when there's fur

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FLEA COMB

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- Rapid combing traps fleas
- Direct examination or KOH prep

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DIASCOPY

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- Useful in distinguishing between hemorrhage and vascular dilation as causes of erythema.
- Blanching = vascular dilation
- Non-blanching = purpura