Dermatology

Question 1

How to reach a diagnosis in dermatology? (4)

Answer 1

● History! ex - alopecia
● Clinical examination
● Lesions and patterns
● Diagnostic tests

Question 2

Dermatological examination includes (5)

Answer 2

● Basic thorough clinical examination
● General skin and hair condition

● Check the ears, paws, between toes,
claws, under the tail…

● Otoscopy
● Describe the lesions

Question 3

myringotomy

Answer 3

is a procedure to create a hole in the ear drum to allow fluid that is trapped in the middle ear to drain out.

Question 4

Lesion distribution can be described as (5)

Answer 4

● Local
● Focal/Multifocal
● Generalized/diffuse
● Symmetric/Asymmetric
● Singular - annular (ring) - linear

Question 5

Understanding which lesions are
primary
secondary
or both

Answer 5

Question 6

Answer 6

Alopecia - hair loss

Could be primary or
secondary (self induced)

Question 7

Answer 7

Alopecia with erythema (self induced (licking), inflammatory)

Question 8

Answer 8

Hypotrichosis - thinning of hair
(a form of alopecia, only partial hair loss)

Question 9

Answer 9

Macule - flat area of color change, less 1 cm

(if its large, then its a patch)

Question 10

Answer 10

Papule - solid elevated lesion, less than 1 cm

(if the lesion contains pus, its a pustule)

Question 11

diascopy

Answer 11

Diascopy is used to determine whether erythema in a lesion is due to blood within superficial vessels (inflammatory or vascular lesions) or is due to hemorrhage (petechiae or purpura).

A microscope slide is pressed against a lesion (diascopy) to see whether it blanches.

If it blanches - its erythema, if it doesnt blanche - its hemorrhage aka bruising.

Question 12

Answer 12

Plaque - flat elevation in skin, more than 1
cm

Question 13

Answer 13

Wheal - elevated, soft lesion, filled with
edema. (urticaria)

Question 14

Answer 14

Epidermal collarette - circular flaky rim

(with hyperpigmentation)

Question 15

vesicle vs bulla

Answer 15

Vesicle - elevation, filled with clear fluid,
less than 1 cm

Bulla - more than 1 cm

Question 16

Answer 16

Scale - loose fragments/flakes of horny
layer

Question 17

Answer 17

Crust- dried exudate, pus, blood etc. ointments and other care products can contribute to the crust accumulation.

Question 18

Answer 18

Excoriation - self induced erosions/ulcers

Question 19

Answer 19

Erosion - shallow epidermal defect, loss
of epidermis, moist, no bleeding, won’t
leave a scar.
e.g. hotspot

Question 20

Answer 20

Ulcer - break in continuity of epidermis,
exposure of dermis.

Question 21

Answer 21

Fissure - linear cleavage into epidermis/dermis

Question 22

Answer 22

Hyperkeratosis - thickening of the stratum
corneum

Question 23

Answer 23

Lichenification - thickening and hardening
of the skin

Question 24

Answer 24

Follicular casting

(a type of hyperkeratosis)

Question 25

Answer 25

Comedones - keratin filled hair follicles

(a type of hyperkeratosis)

Question 26

Skin cytology aims to

Answer 26

To evaluate cells (infections, inflammation, neoplasias etc).

You need glass slides, STAINS and technique depending on the area: Dry or moist lesion? Crusts or scales? Paws, lip folds, fistulas?

On microscope use high magnification (100x) and immersion oil!

A few malassezia, bacteria (mostly cocci) is normal!

1-3 per view (100X). Abnormal amounts, inflammatory cells, phagocytosis are all finds.

Question 27

How to collect cytology (4) options:

Answer 27

1) Tape strip/acetate tape
2) Q-Tip
3) Direct smear
4) Fine needle aspirate FNA

Your technique will depend on the nature of the lesion and the location.

Question 28

Skin scrape Often used for

Answer 28

diagnosing ectoparasites (demodicosis, sarcoptosis, cheyletiellosis, notoedrosis).

You need mineral oil, scalpel blade, glass slide + cover slide.

(Pinch the skin), moisten the scalpel blade with mineral oil, scrape until capillary bleeding. Hold 45 to 90 degree angle,
direction of hair growth.

You put the sample onto the glass slide, that has a drop of oil on it. NO STAINS!

Look with low power objective (5X, 10X), low light or close iris diaphragm (more contrast)
Look through whole slide either horizontally or vertically.

Deep vs surface. Method and area of interest depends on suspected disease.

Example, for sarcoptic mange - at least 5 deep scrapes (until capillary bleeding). Neg. result does not rule it out.

Question 29

Where to collect your ear sample from?

Answer 29

Take the sample from the point where vertical ear canal turns to o horizontal ear canal.

Question 30

Ear swabs for parasites. Explain technique.

Answer 30

For parasites - use mineral oil, coverslide, low power (5-10X).

Question 31

Ear swabs taken for cytology..

Answer 31

Cytological evaluation - may need to be heated (be cause cerumen melts and stain gains access to cells). STAINING. High power (100X).

Question 32

Flea Comb Test, explain the steps.

Answer 32

● You take wet white paper.
● You comb the animal with a flea comb, and place all the hair, scales, dirt on the white
paper.
● Fleas are not always visible!
● Flea dirt bleeds into the paper!

Question 33

Dermatophyte test is a

Answer 33

test to culture dermatophytes.

DTM - agar (dermatophyte test medium) for growing dermatophytes.
Contains indicator that changes color.

Question 34

Dermatophyte test:
McKenzie technique

Answer 34

(toothbrush method)

Comb the animal for several minutes with sterile toothbrush (new brush). Put
all the hairs, scales onto DTM (dermatophyte agar).

Roth technique: Press acetate tape to colonies growing on the agar, stain them (blue) and microscope.

Question 35

Bacterial culture and sensitivity

Answer 35

Most of the bacterial skin diseases in dogs are caused by Staphylococcus pseudintermedius.

Culture and sensitivity is used when treatment is failing, there are rod shaped bacteria seen on skin cytology, long antibiotic courses in furunculosis.

Sample is collected with q-tip and transport medium is used to send to laboratory.

Good places to sample are intact pustules, draining tracts.

To evaluate deep infections, sometimes biopsy is taken and used for culture.

Question 36

Treatment trials are used to

Answer 36

rule out some parasites (canine scabies, fleas in cats).

Question 37

Elimination diet is

Answer 37

diet trial is used to investigate food allergy. There are no reliable tests/blood
tests to diagnose food allergy!

Animal must go through elimination diet with completely new components/hydrolyzed dry food.

Diet will last for 8 weeks. All food, treats, medication, tooth paste must be new or ruled out.

Provocation must be done afterwards!

Question 38

Allergy skin testing/serum testing

Answer 38

Is used for therapy - allergen specific
immunotherapy.

Animal must be weaned from
corticosteroids!

Question 39

hyperestrogenism

Answer 39

occurs in male dogs due to testicular sertoli cell tumor (sometimes origin other cells)

these dogs are frequently old cryptorchids

can manifest as skin issues, anemia etc.