What is skin scraping?
A skin scraping is a basic dermatological procedure. It is
performed using a blade, a glass slide, and mineral oil. The skin
is scraped either superficially or deep to search for mites
(parasites) that live on the skin surface or hair follicle,
respectively. This procedure is not intended to cut the skin, but
rather scrape the skin. The area scraped will look like an abrasion
(when you "skin" your knee) once completed. The sample is gathered
on the glass slide with mineral oil and examined under a
LEFT: Demodex Mites.
RIGHT: Scabies Mite.
What is cytology?
Skin cytology is a basic dermatological procedure. It can be
performed in several ways but the intent is the same, to collect a
sample in search of cells and micro-organisms (bacteria and yeast)
which may be contributing to the skin or ear condition. One
technique is to rub a glass slide on a lesion (sore). Another way
is to repeatedly press clear acetate tape on a lesion and then
fixing the tape to a slide. Lastly, a cotton swab (especially for
ears and body folds) or blade may be used to smear collected
contents on a glass slide. Regardless of the technique, each slide
is stained and examined under the microscope.
What is skin biopsy?
A skin biopsy is a procedure used by dermatologists to collect a
small sample of full-thickness skin. This is usually done after
other diagnostics such as skin scraping and cytology have already
been performed. In many cases, several small samples (about the
size of pencil eraser) are obtained using a biopsy punch. Other
times, a larger skin sample may be necessary. The skin is then
closed with a couple of sutures (stitches) which will need to be
removed several days later. Depending on the body location being
biopsied, a local anesthetic (skin numbing agent such as
lidocaine), brief sedation, and/or general anesthesia is required
to minimize the patient's pain and anxiety involved in sample
collection. In many instances, minimal clipping of fur is necessary
to assure a good biopsy sample. Once the biopsy is collected, the
dermatologist sends the tissue to a dermatopathologist (pathologist
who specializes in skin disease) for processing, microscopic
evaluation, and interpretation. This process generally takes about
one week. Skin biopsy is particularly useful for evaluating
potential auto-immune skin diseases, hair follicle disorders, deep
infections, and cancer. Often, the skin biopsy will allow the
dermatologist to exclude several serious skin diseases if a
specific cause cannot be identified.
Punch biopsy taken from a miniature horse.
What is video otoscopy?
Video otoscopy allows the dermatologist to magnify and examine
the external canal and tympanic membrane (ear drum) in a patient's
ear. The video otoscope is a small, cone-shaped camera that is
placed in a patient's ear canal allowing the dermatologist to
visualize and assess the presence and extent of disease. Depending
on the nature of the patient, sedation may be necessary during
examination. Video otoscopy is frequently used to help determine
what may be contributing to patient's ear disease. It can allow the
dermatologist to see whether there is swelling or even if a growth
is present in the ear. Likewise, the magnified field of view helps
the dermatologist collect samples for culture and biopsy when
necessary. Video otoscopy is also utilized during irrigation
(flushing) of the external ear canal and middle ear. This allows
the dermatologist to assure correct placement of cleaning tools and
adequate removal of debris from the ear canal. An added feature of
the video otoscope is that it has the ability to take pictures of
your pet's ear canal to illustrate what the dermatologist is
seeing, and document the severity of disease so treatment response
can be assessed in the future.
LEFT: Normal ear canal.
RIGHT: Ear cleaning procedure.
What is skin testing?
Intradermal testing (IDT) or allergy skin testing is a tool that
aids the dermatologist in the selection of environmental allergens
(pollen, mold, mites, insects, dander) for subsequent immunotherapy
(allergen-specific allergy shots). This test followed by
tailor-made allergy shots is best performed after other
possibilities for the itchy skin disease have been excluded.
Veterinary IDT is similar to human allergy skin testing; however,
our patients need sedation and clipping. The side of the chest will
be shaved in the shape of a rectangle and small black Sharpie pen
dots will be put in a linear array on the shaved skin allowing us
to know where to make each injection. A panel of allergens is then
injected in the skin. The size of any developing wheals is
recorded. The entire procedure last approximately 30 minutes.
Importantly, this test is used for environmental allergies (atopic
dermatitis), not food-related allergies.