Week 6 - Hair, swabs and impressions

Alopecia

Loss of hair of fur

Pruritis

Itching of the skin

Otitis

Inflammation of the ear

Pyoderma

Bacterial skin infection with pus formation

Erythema

Redness of the skin from increased blood flow

Pododermatitis

Inflammation of the skin on the paws

Atopy

Genetic tendency to develop allergic skin disease

Hyperkeratosis

Thickening of the outer skin layer

Urticaria

Hives

Seborrhea

Excessive scaling or greasiness of the skin

What are the 6 techniques of skin sampling?

Swabs, direct impressions, hair pluck, tape impression, coat brushing, skin scrapes

What equipment is needed for tape impression

• Gloves

• Clippers

• Tape

• Slides

• Diff quick

• Immersion oil

• Microscope

What is the method of tape impression?

1. Apply tape onto skin area

2. Ensure to not to touch sticky side of tape

3. Rub tape with thumb nail to ensure good contact

4. Diff-quick

5. Can be examined under oil immersion for bacteria and yeast

What can you see x4,x10,x40 lens?

Superficial ectoparasites e.g. fleas, lice, flea dirt

What can you see x100 lens and oil immersion?

Bacteria, fungi spores, yeasts, cells

What are the advantages of tape impressions?

• Non-invasive

• Cheap and quick

• Good for hard to access areas (skin folds/interdigital)

What are the disadvantages of tape impression?

• Hard to get large population

• Misses burrowing parasites

• Contamination from samples

• Tape reaction

What equipment is needed for direct impressions?

• Gloves

• Clippers

• Slides

• Diff quick

• Immersion oil

• Microscope

• Needle

What wounds are good to use direct impressions?

Exudative lesions

What can you do with a needle for non-exudative lesions before direct impressions?

Pick the wound to express fluid

What is the method of direct impressions?

• Gently press the slide onto lesion

• Air-dry

• Stain with diff-quick

• Examine on low power first then high power/oil immersion

What can you see on x100 lens on direct impressions?

• Bacteria, fungi and yeast

• Inflammatory cells: neutrophils, eosinophils, lymphocytes, macrophages

• Pre-histology smears from biopsies - mast cell tumours

What are the advantages of direct impressions?

• Non-invasive

• Not stressful

• Quick, cheap, and easy

• Good for moist lesions

What are the disadvantages of direct impressions?

• Miss parasites

• Not good for hard to reach areas

• Slide can snap

What equipment is needed for hair brushing?

• Gloves

• Flea comb

• Hairbrush

• White paper

• Paraffin

• Slides

• Coverslips

• Diff-quick

• Microscope

What is the method of hair brushing?

1. Brush hair over black consulting table or white/brown paper for 5 minutes

2. Place hairs in Petri dish, cover in liquid paraffin

3. Place scale/parasites on slide with liquid paraffin

4. Apply cover slip

What can you see on x10, x40 lens for hair brushing?

Superficial ectoparasites: fleas, flea dirt, cheylietella, lice

What are the advantages of hair brushing?

• Non-invasive

• Not stressful

• Quick, cheap and easy

• Good for diagnosing surface ectoparasites: harvest mites, ticks, lice, fleas

What are the disadvantages of hair brushing?

• Not good at getting burrowing parasites

• Not good for cytology

What is another name for hair pluck?

Trichogram

What mite likes to burrow near the hair follicle?

Demodex

What equipment do you need for a hair pluck?

• Gloves

• Forceps

• Slides

• Paraffin

• Cover slips

• Microscope

What is the method for hair pluck?

• Use forceps to pluck hair in an alopecic (since parasites are most likely to be sat here)

• Place onto a slide and evaluate under low power

Analyse what is in this photo

Demodex

Analyse what is in the photo

Colour dilution alopecia

Analyse what is in the photo

Broken ends - self trauma

Analyse what is in the photo

Tapered ends - endocrine/inflammation

Analyse what is in the photo

Dermatophyte (fungal) spores

What is are the advantages of hair pluck?

• Non-invasive

• Quick,cheap and easy

• Good for diagnosing Demodex

• Good for hard to access areas

What are the disadvantages of hair pluck?

• Uncomfortable for patients

• Miss surface parasites

• Not good for cytology

• Temperament needs to be considered

What equipment is needed for skin scrapes

• Gloves

• 10 blades

• Slides

• Paraffin

• Cover slips

• Microscope

Who would you do a superficial and deep skin scrape on?

Pruritic/scay

What are the 3 mites that can be found on a superficial scrape?

Cheyletiella, sarcoptes scabei, notoedres cati

How to do the method of deep skin scrapes?

• Squeeze prior to scraping, scrape until capillary oozing

• Must scrape on 5 or more locations

What can you diagnose with a deep skin scrape?

Demodex

What mite is this and where would you find it?

• Notoedres cati

• Head and neck

What mite is this and where would you find it?

• Cheyletiella

• Dorsum, areas of dandruff/scale

What mite is this and where would you find it?

• Sarcoptes scabei

• Lateral elbow, lateral hock and pinnae

What mite is this and where would you find it?

• Demodex

• Alopecia margins, comedones

What are the advantages of skin scrapes?

• Quick, cheap and easy

• Good to diagnose Demodex and burrowing parasites

What are the disadvantages of skin scrapes?

• Invasive

• Uncomfortable - sedation might be needed

• Not for surface parasites

• Creating a wound = risk of secondary infection

• False negatives (Shar Peis have thick skin)

What equipment is needed for swabs?

• Gloves

• Plain swabs/cotton buds

• Slides

• Cover slips

• Diff quick

• Microscope

What is the method for swabs?

• Rub swab over skin/gently around external ear

• If dry area swab or location can be re moistened with saline/paraffin

• Roll swab alongside

• Can also suspends large blobs or earwax in paraffin

• Add cover slip

What can you analyse with x10,x40 lens?

Otodectes cynosis

What can you see on x100 lens?

• Fungi - ringworm

• Yeast - malassezia

• Bacteria

• Inflammatory cells

What are the advantages of swabs?

• Quick, cheap and easy

• Good for cytology

• Good for hard to access areas such as ears

• Can be sent off to external lab

What are the disadvantages of swabs?

• Can be uncomfortable

• Risk of contamination

• Not deep parasites

What are the advantages of Wood’s lamp?

• Quick and easy

• Non-invasive

• Rapid diagnosis of dermatophyte infections

What are the disadvantages of Wood’s lamp?

• False + / -

• 30%-70% sensitivity for microsporum canis

• Microsporum gypseum and trichophyton mentagrophytes do not fluoresce

• Lint, dander and organic debris can fluoresce = false +ve

What method of sampling would you use for pruritis and scaling?

Scrape and tape

What method of sampling would you use for an exudative lesion?

Direct compression and swab

What method of sampling would you use for suspected dermatophyte?

Direct compression and tape

What method of sampling would you use for suspected Demodex?

Skin scrape and hair pluck