Dermatologic Dx & Dz-5

What are the skin related issues (5)

allergies, infection, parasites, autoimmune, neoplasia

What are the dermatology diagnostics? 5

1. blood test

2. cytology - ear&skin swabs

3. culture & sensitivity - bacterial

4. fungal culture - dermatophyte

5. dermatohistopathology - SPECIAL

What is a allergy blood test? for who?

ELISA detects allergen-specific IgE antibodies, uses high-affinity IgE receptor to test dozen allergens

• available for dogs, cats, horses

• not recommended b/c low accuracy= high false positives

what is Intradermal testing?

used to diagnose environmental allergies NOT for food allergies, performed by boarded dermatologist

• thorax shaved no scrub, use 26 g needle, .05 mL

• + control = histamine & - control = saline

• monitor 15&30 min

What type of allergy is evaluated with intradermal testing?

environmental allergies

What is the purpose of tuberculin skin test? common? tuberculin injected where? results?

tests for tuberculosis, it is zoonotic

• common test in cattle and primates

• tuberculin is injected interdermally in cervical region or skin fold at tail base

• results within 48-72 hr later, a + will have inflammatory

What can you learn from cytology of a skin lesion?

Can reveal

• bacteria → staphylococcus

• yeast → malassezia pachydermatis

When should you run a bacterial culture and sensitivity? What are the limitations?

When there is severe, deep, complicated skin infections

• use culturette swab

• sensitivity results → only systemic, does not apply topical meds

• cultures are difficult to interpret for ears/skin

How is a fungal culture (DTM) performed and what does a positive result look like? sample?

DTM = dermatophyte Test Medium

• inhibits bacterial growth, turning red at presence of dermatophytes

• Sample→ hair w/ forceps or broken hair shafts, results 2-3 wk

What is a fungal PCR? + result?

Ringworm PCR detects fungal DNA

• fast results in 1-3 dy

• a + show microsporum and trichophyton

• has a 95-99%

What is the purpose of a Wood’s lamp? What species of ringworm does it detect?

Used to diagnose ringworm and detects 80% microsporum canis but not detect trichophyton

• a + will appear apple green

• a - will appear just lint or organic debris

What are the 4 ways to detect parasites and what do they evaluate for?

1. scrape → evaluates for deep & superficial mites, scrape until capillary blood seen

2. tape → cellophane captures superficial mites only

3. pluck → evaluates for demodex, fungal spores

4. comb → fleas, flea eggs, superficial mites

What type of test is run on skin biopsy?  How is it different from other biopsy testing?

Dermatohistopathology

• has special submission with photos submitted

What are hot spots/ pyoderma?

moist, red, skin rash

• pop up overnight

• common in warmer months

• culture is severe

What is malassezia dermatitis

it is overgrowth of malassezia pachydermatis, related to allergies

• tx: topical medications

What is Atopic dermatitis

allergies triggered by environmental antigens

• dx: minimum database, cytology, intradermal skin testing

• tx: allergen specific immunotherapy

What is food allergy dermatitis

allergies triggered by dietary allergens - usually proteins

• dx: using elimination trial

• tx: typical derm workup or hypoallergenic diet

What is eosinophilic granuloma complex

It is feline disease related to allergies, commonly fleas, mosquito or mite bites

• its formation of granulmas, plaques

• dx: dermatohistopathology

• tx: prevention of bites

Who is more prone to dermatophytosis ringworm and the diagnostics?

Cats more prone

• dx: woods lamp, DTM culture and PCR

• tx: antifungal therapy for cats