Skin and hair

Question 1

Why might a vet perform a dermatology exam?

Answer 1

Ecto-parasites

Skin lesions

Pruritis

Neoplasia

Chronic dermatitis

Erythema

Question 2

Describe patient preparation for dermatology exams

Answer 2

Skin/hair ample should be performed prior to administration of drug therapy if possible

Ideally, patient should be ‘drug free’ for a 7-10 day period prior to sampling

Patients should be suitably restrained but handled by as few staff as possible

Patients skin should NOT be clipped, scrubbed or washed prior to obtaining sample

Question 3

Consider healthy and safety for a dermatology exam

Answer 3

Potential risk of zoonosis and cross contamination so PPE very important- clients should also be aware

Equipment and surfaces thoroughly disinfected and sterilised after use and dispose of used single used equipment

Question 4

Describe dermatitis

Answer 4

Reddening and swelling of the skin from direct irritation by an external agent or allergen

Question 5

Describe lesions

Answer 5

Tissue abnormality commonly caused by disease or trauma

Question 6

Describe a rash

Answer 6

Widespread eruption of lesions

Question 7

Describe erythema

Answer 7

Reddening of the skin due to increased blood supply

Question 8

Describe a skin cyst

Answer 8

A papule containing fluid of semi solid material e.g. epidermoid and pilar cysts

Question 9

Describe pyoderma

Answer 9

Primary skin infection, commonly staphylococcal or streptococcal

Question 10

Describe a papule

Answer 10

Small, palpable lesion, raised above the skin

Question 11

Describe a pustule

Answer 11

Purulent vesicle (pus filled sac)

Question 12

Describe plaque

Answer 12

Palpable, flat lesion, greater than 0.5mm in diameter

Question 13

Describe atopy

Answer 13

Localised hypersensitivity reaction to an allergen

Question 14

Describe lichenification

Answer 14

Seen with chronic atopy

Question 15

Describe alopecia

Answer 15

Hair loss

Question 16

Name skin sampling techniques

Answer 16

Skin scrapes

Hair brushing

Cytaneous cytology

• Tape impressions
• Hair plucks
• Swabs

Skin biopsy

Question 17

What are the advantages of a skin scrape?

Answer 17

Quick and easy

Generally painless

Often examined in house

Minimal trauma

RVN can perform under vet instruction

Sedation not normally required

Allows examination of full thickness of epidermis and hair follicles

Used to detect cuticular and sub-cuticular parasites

Question 18

Describe a superficial skin scrape?

When should you do one?

Answer 18

Superficial skin scrape that does not enter the epidermal layer of the skin

One every patient with scaly or pruritic skin

Question 19

What may you find from a superficial skin scrape?

Answer 19

Sarcoptes scabeii

Cheyletiella sp.

Notoedres cati.

Dermatophyte spore infested hair shaft

Lice

Question 20

Describe sarcoptes spp.

Answer 20

Intensley itchy, highly contagious and zoonotic mite is transmitted via direct contact

Lesions develop over ventral chest and abdomen, elbows, leg and ears

Question 21

How else could you test for sarcoptes spp.?

Answer 21

Sarcoptes antibodies can be detected using ELISA technology

Question 22

Describe a deep skin scrape

When should you do one?

Answer 22

Allows collection of sample from air follicle, results in light capillary ooze. Squeeze the skin prior to sampling

When should I do it?
Non-inflammatory and inflammatory alopecia
Pustules
Crusts

Question 23

What might a deep skin scrape find?

Answer 23

Demodex sp.

Question 24

How would you choose a sampling site for a deep skin scrape?

Answer 24

Head, eats and feet are commonly affected

Areas of erythematous skin

Papules, scales or crusts

Areas of alopecia

Question 25

Describe demodex

Answer 25

A mite that often presents with hair loss beneath or around the eyes In severe cases, the whole body is affected Not pruritic but secondary pyoderma is

Question 26

What are the advantages of hair brushing?

Answer 26

Quick and easy No sedation required Patient enjoys Can be examined in house RVN can perform under vet instruction Non traumatic Inexpensive Allows collection of cutaneous parasites

Question 27

When should you do a hair brushing sample?

Answer 27

Generally itchy patients Patients with suspected flea infestation Patients with excess scurf

Question 28

What might a hair brushing sample find?

Answer 28

Ctenocephalides Flea excrete/debris Cheyletiella sp. Dermatophytes

Question 29

Describe the hair brush sampling technique

Answer 29

Put on gloves Stand the animal over white background i.e. white paper or tissue and restrain properly Brush coat with fine toothed comb to collect debris Place sample collected on the comb and any collected on the paper into a labelled, sterile container Wetting black particles may indicate the presence of fleas if the dampened particle leaves a red mark on the paper

Question 30

Describe the microscopic evaluation technique

Answer 30

Place a cover slip on to the microscope slide, over a portion of the collected sample Examine on low power x4-x10 under the microscope using the battlement technique Record the vernier scale, if parasite identified, to allow relocation If large amount of hair is collected, a hand lens can be used

Question 31

Describe cheyletiella spp.

Answer 31

'Walking dandruff' causes skin irritation and dandruff Transmitted directly or indirectly (from bedding) Causes itchy, flaky skin, sometimes with raised spots and scabs Commonly affects the dorsal trunk, however infestation of nasal passage may occur, causing sneezing Humans are at risk of transient infection Produces pruritic lesions on arms, legs, trunk and buttocks

Question 32

Describe cutaneous cytology

Answer 32

Impression smear Aspiration smear Sterile cotton tip

Question 33

When should you do cutaneous cytology?

Answer 33

When bacterial or yeast infection is suspected (pustules,papules, scales, ulcers, crusts) Nodules or tumours Otitis externa

Question 34

What might you find from cutaneous cytology?

Answer 34

Cocci and rod shaped bacteria Inflammatory cells, eosinophils, macrophages Malassezia Neoplastic cell

Question 35

Describe impression smear sampling

Answer 35

A strip of scotch tape can be pressed onto area to collect cells and surface organisms Glass side can be rubbed onto moist, exuding skin or greasy surface of infected skin Clean cotton bud can be rolled onto surface of skin or into ear canals, then roll tip onto glass slide to transfer for examination Dampen cotton tip with sterile water and rub between digits to obtain inter-digital cutaneous samples Insert a 25-27g needle into pustule, parallel to the skin to avoid involvement of deeper cells Take impressed of ruptured pustule using glass side

Question 36

Describe slide evaluation

Answer 36

Air dried slides can be stained using the 'diff quick' technique and examined under oil immersion Tape samples can be adhered to the slide and will act as cover slip

Question 37

Describe malassezia pachydermatitis

Answer 37

Yeast infection which can be both commensal and pathogenic Very low risk zoonosis documented in immuno-compromised humans Commonly occurs in atopic animals with immu-compromise, affecting the skin and eat canals Can present in low numbers on normal skin, infection is indicated by increased numbers on sample

Question 38

What are the advantages of a Trichogram (hair pluck)

Answer 38

Inexpensive Quick and easy Minimal trauma Can be examined in house Often sedation not required RVN can do

Question 39

When should you do a Trichogram?

Answer 39

In patients with alopecia - look at hair bulbs (3 stages of hair growth cycle) In patients with broken hair tips - indicating self trauma Suspected dermatohytosis To identify colour dilution alopecia Alternative to deep skin scrape in suspected demodex

Question 40

What might you find from a trichogram?

Answer 40

Broken hair tips - indicating self trauma Demodex Hair shafts covered in dermatophyte spores or positive for ringworm culture Melanin clumped into hair shaft -indicating colour dilutionalopecia Cheyletiella sp.

Question 41

Describe a culture for dermatophytosis

Answer 41

Dermatophyte test medium can be used to identify ringworm from a hair pluck and mackenzie brush samples Specialised agar which is based on sabourauds dextrose agar is used, this contains bacterial inhibitors pH indicators are incorporated to produced a colour change from amber to red - when fungal growth produces alkaline by products (ringworm) and no colour change - when fungal growth produces acid by products

Question 42

Describe the Mackenzie brush technique

Answer 42

If no lesions are present, a sterile toothbrush is used to brush the affected area for 5 minutes Imbedded the brush and sample into the culture media, sterile forceps can be used to dislodge debris and hair from the brush onto the agar