Skin and hair Flashcards
Why might a vet perform a dermatology exam?
Ecto-parasites
Skin lesions
Pruritis
Neoplasia
Chronic dermatitis
Erythema
Describe patient preparation for dermatology exams
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
Consider healthy and safety for a dermatology exam
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
Describe dermatitis
Reddening and swelling of the skin from direct irritation by an external agent or allergen
Describe lesions
Tissue abnormality commonly caused by disease or trauma
Describe a rash
Widespread eruption of lesions
Describe erythema
Reddening of the skin due to increased blood supply
Describe a skin cyst
A papule containing fluid of semi solid material e.g. epidermoid and pilar cysts
Describe pyoderma
Primary skin infection, commonly staphylococcal or streptococcal
Describe a papule
Small, palpable lesion, raised above the skin
Describe a pustule
Purulent vesicle (pus filled sac)
Describe plaque
Palpable, flat lesion, greater than 0.5mm in diameter
Describe atopy
Localised hypersensitivity reaction to an allergen
Describe lichenification
Seen with chronic atopy
Describe alopecia
Hair loss
Name skin sampling techniques
Skin scrapes
Hair brushing
Cytaneous cytology
- Tape impressions
- Hair plucks
- Swabs
Skin biopsy
What are the advantages of a skin scrape?
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
Describe a superficial skin scrape?
When should you do one?
Superficial skin scrape that does not enter the epidermal layer of the skin
One every patient with scaly or pruritic skin
What may you find from a superficial skin scrape?
Sarcoptes scabeii
Cheyletiella sp.
Notoedres cati.
Dermatophyte spore infested hair shaft
Lice
Describe sarcoptes spp.
Intensley itchy, highly contagious and zoonotic mite is transmitted via direct contact
Lesions develop over ventral chest and abdomen, elbows, leg and ears
How else could you test for sarcoptes spp.?
Sarcoptes antibodies can be detected using ELISA technology
Describe a deep skin scrape
When should you do one?
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
What might a deep skin scrape find?
Demodex sp.
How would you choose a sampling site for a deep skin scrape?
Head, eats and feet are commonly affected
Areas of erythematous skin
Papules, scales or crusts
Areas of alopecia
Describe demodex
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
What are the advantages of hair brushing?
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
When should you do a hair brushing sample?
Generally itchy patients
Patients with suspected flea infestation
Patients with excess scurf
What might a hair brushing sample find?
Ctenocephalides
Flea excrete/debris
Cheyletiella sp.
Dermatophytes
Describe the hair brush sampling technique
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
Describe the microscopic evaluation technique
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
Describe cheyletiella spp.
‘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
Describe cutaneous cytology
Impression smear
Aspiration smear
Sterile cotton tip
When should you do cutaneous cytology?
When bacterial or yeast infection is suspected (pustules,papules, scales, ulcers, crusts)
Nodules or tumours
Otitis externa
What might you find from cutaneous cytology?
Cocci and rod shaped bacteria
Inflammatory cells, eosinophils, macrophages
Malassezia
Neoplastic cell
Describe impression smear sampling
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
Describe slide evaluation
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
Describe malassezia pachydermatitis
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
What are the advantages of a Trichogram (hair pluck)
Inexpensive
Quick and easy
Minimal trauma
Can be examined in house
Often sedation not required
RVN can do
When should you do a Trichogram?
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
What might you find from a trichogram?
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.
Describe a culture for dermatophytosis
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
Describe the Mackenzie brush technique
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