Dermatological Flashcards
what is included in dermatological anatomy?
skin, fur, and nails
what are the skin’s functions?
protection, environmental protection, regulate temperature, produce pigment/ vitamin D, sensory
epidermis
most superficial skin layer, made up of cell layers, most layers are filled with keratin which protects the inner layers of the skin
dermis
middle skin layer, provides strength to the skin
fatty layer
most inner layer of skin, connects dermis to underlying muscles
what is the different between human and dog skin?
human skin is more acidic, dog skin has a pH of 7 while human skin has a pH of 5, dogs also have a thinner epithelium
apocrine sweat gland
oily secretions, empty into hair follicle, associated with haired skin
eccrine sweat gland
connect to skin surface, associated with non-haired skin
sebaceous sweat gland
contain sebum, associated with haired skin
where are animals’ sweat glands located?
paw pads and nose
what are the two classifications of skin lesions?
primary: disease causes lesions
secondary: something else causes lesions
what are the CS of dermatitis?
pruritic, erythema (redness), heat to an area
superficial dermatitis
“hot spot”, “acute moist dermatitis”; affects head, face, limbs, hips; blows up overnight
flea allergy dermatitis (FAD)
caused by an allergy to antigens found in flea saliva, causes intense pruritis
atopic dermatitis
caused by an allergy to an environmental thing or something inhaled/ ingested; affects 5 Fs: face, feet, folds, friction points, flexure points; 90% of cases are caused by allergy to something inhaled/environmental allergies; only 10% of cases are food allergies
pododermatitis
inflammation of skin of feet; CS: edematous (swelling), erythematous, pruritis
abscess
cellular fluid accumulation that is walled off, CS: edematous, erythematous, heat
papule
small raised lesion, <1cm, looks like a solid pimple or swelling, often forming part of a rash and typically inflamed but not pus producing, seen with infections and environmental/ contact allergies
plaque
flat elevation, >1cm, like an enlarged papule
pustule
small blister/ pimple containing pus, linked with skin infections and skin parasites
comedones
blackheads, caused by hair follicle being blocked and sebum can’t escape, linked with demodex (type of mite) and exocrine disease
macules and patch
flat non-palpable change in skin color, macule: <1cm, patch: >1cm
vesicle
small fluid-containing blister within epidermis
bulla
large >1cm acellular fluid-containing blister that extends into the dermis
erosion
break in continuity of epidermis that doesn’t penetrate basement membrane
ulcer
break in continuity of epidermis that penetrates basement membrane
decubital ulcer
ulcers formed by pressure on bony prominences, often occur in recumbent patients, similar to bed sores in humans
excoriation
self-induced injury to skin due to moderate-severe pruritis
wheal
flat elevation caused by edema, causes swelling in the dermis, resolves on their own, linked to bug bites and reactions
urticaria
multiple wheals/ hives present
cyst
sac containing fluid or solid material, has a cystic lining that must be completely removed so the cyst doesn’t come back
nodule
typically >1cm, deep solid accumulation of cells
tumor
abnormal uncontrolled tissue growth, can be benign or malignant, can affect cutaneous or subcutaneous
scales
increase in keratinocytes that produce thin fragments, seen with walking dandruff and inflammation
crusts
dried out pustule or exudate that oozed through epidermis, can be associated with chronic skin infections`
collarette
circular lesion with circular rim of scales and/or peeling edge, footprint of a pustule
alopecia
hair loss
what are the different types of alopecia?
multi-focal/patchy (patches of hair loss), diffuse partial (affects scalp in general distribution), generalized complete (little to no hair left)
which type of alopecia can be an early sign of FAD?
diffuse partial
alopecia X
trunk and body naked but fur is still on head and feet, often comorbid with pigmentation issues
seasonal flank alopecia
hair loss linked with change in season and day cycle, is bilateral (affects both sides), common in boxers
lichenification
thickened skin, result of chronic trauma to skin, can occur anywhere there’s epithelium (often ears and abdomen), common in Westies
fissure
linear tear that extends through epidermis into dermis
seborrhea
increased scale formation, excessive greasiness and stinks, treat with anti-seborrhea shampoo
what is an important PPE needed for dermatological procedures?
gloves
what equipment is used to do a skin scraping?
10 scalpel, glass microscope slide, mineral oil
how do you do a skin scraping?
- dull blade
- 1-2 drops of mineral oil on slide and dip blade in oil
- pinch and roll skin
- hold blade between thumb and pointer finger
- using 30 degree angle quickly scrape skin against grain of fur
- continue until capillary destruction/ blood
- wipe on slide
sarcoptic mange
sarcoptes scabiei mite
wide and superficial, for skin scraping focus on crusts, papules, areas of alopecia, and areas of intense pruritis
located on elbows, ears, and ventral trunk
demodectic mange
demodicosis (demodex sp.)
for skin scrape: deep, reroll skin
located on face (around mouth, eyes, forelimbs), seen in stressed, immunocompromised animals, and before heat, CS: patchy alopecia, erythema, scales, comedones
what equipment is needed for a cellophane tape test?
clear cellophane tape and a microscope slide
how do you do a cellophane tape test?
- part hair
- stick 1”-2” piece of tape on area
- put on slide and examine under microscope
cheyletiella mites
“walking dandruff”
zoonotic, affects cats and rabbits, CS: scales, erythema, alopecia
what usually causes dermatitis?
bacteria
how do you take a bacterial skin culture?
clip hair around pustule, cleanse clipped area with 70% alcohol, let skin dry completely, insert swab into pustule after puncturing with #11 blade or 22G needle, inoculate material into culture media, cleanse open pustule with 70% alcohol
what type of lesion is a bacterial skin culture collected from?
purulent lesion
what test is used to take a fungal culture?
dermatophyte test medium (DTM)
what materials are needed for a bacterial skin culture?
cotton soaked in 70% alcohol, culture media, 22G sterile needle or scalpel blade #11
how do you perform a fungal culture?
cleanse edge of lesion with cotton moistened with water, scrape or pluck several hairs from edge of lesion, inoculate dermatophyte culture medium with hairs by tapping hairs on surface of medium, place cover on but not too tight, incubate at room temperature and check daily for growth for 10-21 days
what is important to know about fungal growth and how does it relate to storage of a fungal culture?
fungi grow with air and in dark places so make sure to not close the lid of the medium too tightly and keep it in a dark cabinet at room temperature
ringworm
fungi
lives off keratin and hair
CS: patchy alopecia, scales, crusts, mild pruritis
what are the 3 species of ringworm?
microsporum gypseum, microsporum canis, trychophyton mentagrophytes
order the 3 species of ringworm from which makes up most cases to least cases
microsporum canis 70%
microsporum gypseum 20%
trychophyton mentagrophytes 10%
what are the two types of fine-needle biopsy?
fine-needle aspiration and fine-needle capillary sampling
what materials do you need for a FNA?
20-22G needle length usually 1-1.5”, 3-6 mL syringe, EDTA, 70% alcohol soaked gauze, microscope slides
what is an EDTA?
an acid that is put in blood tubes because it is an anticoagulant
how do you perform an FNA?
prepare, stabilize the area, insert needle, aspirate and release plunger, redirect, aspirate and release plunger, repeat this at least 4 times, remove syringe, detach needle, retract plunger and fill syringe with air, reattach needle and blow contents onto slide
what lesions are an FNA good for?
dense lesions that are highly cellular, lesions with low blood supply, fluid filled lesions
when should fine-needle capillary sampling be used?
for lesions that are suspected to be highly vascular (high blood supply) and when pressure could rupture the cells
if taking a biopsy of a lymph node always use fine-needle capillary sampling
how do you perform a fine-needle capillary sampling?
prepare, stabilize the area, insert needle only (no syringe attached), aspirate and redirect, repeat at. least 4 times, remove, attach air-filled syringe to needle, blow contents onto slide
what are the two types of skin biopses?
punch biopsy and cutaneous wedge biopsy
what are punch biopsies measured in?
mm
who does skin biopsies?
DVM only
what tool is used for a punch biopsy?
Keyes punch biopsy
what type of sample is taken from a punch biopsy?
small sample of full thickness
how do you perform a punch biopsy?
prep, press punch biopsy to site and rotate until entire skin is punctured, remove punch from site and hold pressure to stop bleeding, pull specimen out if needed, blot specimen on paper to remove excess blood, make impression smear, suture skin incision
how do you perform a cutaneous wedge biopsy?
anesthetize skin, perform bread loafing (slice the skin like slices of bread into 5mm sections)
what is cutaneous wedge biopsy used for?
deeper lesions
