Skin and Hair Sampling Flashcards
What equipment would you need to set up for all skin and hair sampling?
PPE - gloves, mask, gown Brush, comb, toothbrush Tape Forceps Paper Biopsy punches - clippers, scrub, stitch up kit Liquid paraffin Microscope slides Surgical blade Swabs
What are coat brushing samples good for?
Useful in diagnosing ectoparasites and their eggs (especially Cheyletiella)
Describe the technique for a coat brushing sample
Part hair
Brush small areas, one at a time, in one direction
Tap the brush onto the petri dish, or onto a microscope slide with liquid paraffin and a cover slip
What can be done to test for fleas?
Put flea dirt onto white paper and dampen - will look like blood
What are the advantages of coat brushing samples?
Easy to perform, can be done in front of owner Non-invasive Not stressful or painful for patient Cheap Quick
What can tape testing techniques used for?
Ectoparasites and some yeasts (if stain the tape)
Describe the technique for a tape test
Part the hair or lightly clip
Gently press the tape on the hair and skin
Stick the tape directly onto a microscope slide if looking for ectoparasites and examine
For yeast, use scotch tape and use a diff-quick method.
What are the advantages of the tape technique?
Cheap
Easy technique
Quick results
Can be used to reach hard to access areas e.g. in between the paw pads
What are the disadvantages of the tape technique?
Can only be used in dry areas
E.g. if there is a ‘raw’ area where secondary infection is present then it wouldn’t be appropriate.
Describe how to perform a hair pluck
Using tweezers or forceps, pluck a clump of hair (and roots!) out and examine. If there are lesions present, take hair from the edge of the lesion.
What is a hair pluck generally used for?
To look for fungal infection or mites that live deep in the hair follicles
What are the 3 ways in which hair plucks can be examined?
- Microscope
- UV light
- Culture
How can hair pluck samples be examined under the microscope?
Grossly to diagnose mites
To look for fungal infections, should be stained with lactophenol cotton blue.
How is UV light used to check hair samples?
Using a Wood’s lamp in a dark room.
Hair may fluoresce a bright apple green if ringworm is present.
50% of Microsporum canis isolates will fluoresce the green colour.
Other things can fluoresce e.g. talc
How would you culture a plucked hair sample?
The suspected hair sample is placed onto a culture plate containing Sabourards agar or Dermatophyte test medium (DTM).
DTM contains an indicator that changes colour from yellow to red in the presence of dermatophytes.
The plate should be incubated at room temperature and be checked on days 7,10 and 14
What are the advantages of a plucked hair sample?
Quick and simple to obtain the sample from the patient
What are the disadvantages of a hair pluck?
Can be painful
Only 50% of cases fluoresce under UV
May get a false positive under UV
Describe the technique of a skin scrape
Scalpel blade is used to scrape the skin surface (deep enough to cause petechial bleeding).
Scraping should be placed onto liquid paraffin
The scraping can be put on a microscope slide for examination under the microscope. View immediately
Scraping should be taken from multiple areas on the body.
What can be diagnosed by skin scraping
Mange mites usually
What are the advantages of skin scraping?
Can diagnose deeper dwelling parasites
Quick results
Done ‘in-house’
What are the disadvantages of skin scraping?
Can be painful/stressful
Need to the correct technique
Need to sample multiple sites
What can you do to prevent dessication of a skin scrape sample if it cant be viewed straight away?
Suspend the sample over a petri dish containing blotting paper soaked with distilled water. Cover with a lid, seal and store in a cool dark place
What is a pustule?
A bulging patch of skin that’s full of pus
Describe how a pustule is sampled?
The contents extracted using a sterile needle and a 1-2ml syringe. It should then be expressed directly onto the microscope slide. It should then be squashed using another slide at a 45 degree angle. Samples can then be viewed at low power or stained and examined under high power.
When are swabs used for sampling?
Generally in hard to reach places like ear canals
How can a swab be tested?
By directly smearing onto a slide and viewing
Or collect and seal sterilely and send away
(if sending for a culture and sensitivity, a charcoal swab should be used)
When is a biopsy punch used?
To take a sample of diseased skin when the skin problems are deeper than the epidermal layer.
Is the patient conscious during a skin biopsy?
It can be done under light sedation and the patient is given a small stitch.
If its in a very sensitive area, it should be performed under GA
What should you remember to do when admitting a patient for biopsies?
Warn the owner that it will look worse before it looks better!
