Dermmmm Flashcards
The epidermis is composed of 4 major “Resident” cell types. List them.
- Keratocytes
- Melanocytes
- Langerhan’s cells
- Merkel cells
List the layers of the epidermis from most superficial to deep
- Stratum Corneum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale
Which of the following makes up 85% of the cells found in the epidermis?
A. Keratocytes
B. Melanocytes
C. Langerhan’s cells
D. Merkel cells
A. Keratocytes
Which layer of the epidermis undergoes mitosis and is responsible for epidermal proliferation?
A. Stratum Corneum
B. Stratum Granulosum
C. Stratum Spinosum
D. Stratum Basale
D. Stratum Basale (deepest layer of the epidermis)
Which layer of the epidermis communicates via desmosomes and is responsible for structural strength?
A. Stratum Corneum
B. Stratum Granulosum
C. Stratum Spinosum
D. Stratum Basale
C. Stratum Spinosum
Which layer of the epidermis has lamellar bodies containing lipids?
A. Stratum Corneum
B. Stratum Granulosum
C. Stratum Spinosum
D. Stratum Basale
B. Stratum Granulosum
Which layer of the epidermis has no nuclei?
A. Stratum Corneum
B. Stratum Granulosum
C. Stratum Spinosum
D. Stratum Basale
A. Stratum Corneum (most superficial skin layer)
Which of the following cells can be found in the dermis?
A. Keratocytes
B. Merkel cells
C. Fibroblasts
D. Lymphocytes
E. A and B
F. C and D
F. C and D
Lymphocytes are found in the DERMIS not the epidermis!!
What is the vascular supply to the dermis?
- Deep plexus (SQ tissue, lots of bleeding if disrupted)
- Middle plexus (Sebaceous glands and hair follicles)
- Superficial plexus (capillary bed, minimal bleeding if disrupted)
Dogs and cats have ________ hair follicles, which is different than cows, horses, shoats and human
Compound
(the others have Simple follicles)
What are the phases of the hair cycle?
- Anagen - growing phase
- Catagen - transitional phase
- Telogen - Resting phase
What smooth muscle originates in the superficial dermis, is connected to hair follicles?
Arrector pili muscle (responsible for goosebumps)
What are the functions of sebaceous glands?
- Produce sebum for biological defenses, pheromones, and gives hair glossiness and strength
What is a macule?
< 1cm, FLAT change in color of the skin
What is a macule > 1cm called?
A patch
(flat change in color of the skin > 1cm)
What is a papule?
RAISED, SOLID, mass <1cm
What is a plaque?
RAISED, SOLID mass > 1cm, can be coalesced papules
(A papule but > 1cm +/- multiple)
What is a vesicle?
Clear, serum filled, RAISED, < 1cm, non-inflammatory lesion
In other words, a blister
If > 1cm its called a bulla
What is a bulla?
Clear, serum filled, RAISED, > 1cm, non-inflammatory lesion
If < 1cm its called a vesicle
What are common locations on the skin for flea allergic dermatitis?
- Dorsum
- Base of tail
- Inguinal region and thighs
What are common locations on the skin for Cheyletiella?
- Dorsum
(walking dandruff)
What are common locations on the skin for Atopic Dermatitis?
- Inner ears
- Face
- Paws
- Axilla
- inguinal region
What are common locations on the skin for Pemphigus Foliaceous?
- Head
- Face
- Nose
- Ears
- Paw pads
- Nail beds
(mucocutaneous junctions)
What is Woods Lamp used for?
- Used to diagnose dermatophytosis (ringworm)
- Specifically Microsporum canis
NB: Only 50-90% of M.canis will flouresce
What can cause a false positive Woods Lamp test?
- Sebum
- Crusts
- Ointments
- Tetracyclines
Explain what occurs with a positive dermatophyte culture
- Changes pH of the medium and therefore changes the color from yellow to red within 10 days
- Look for white fluffy colonies of M. canis
What diagnostic if helpful to examine hair?
Trichogram
How do Anagen hairs appear when using Trichogram?
Curved bottom, golf club appearance
How do Telogen hairs appear when using Trichogram?
Thick, arrow head shaped root with less pigmentation
What techniques can be used for cytology from skin samples?
- Impression smear
- Tape prep
- FNA
(then stain using Diff Quick)
You collect an ear swab from a Cocker spaniel and make a cytology sample using Diff Quick staining. You see footprint shaped organisms under the microscope. What is it?
Malassezia (yeast infection)
What is the name of the most common flea in dogs and cats?
Ctenocephalides felis
What skin lesions are good for impression smears?
- Moist lesions and pustules
What skin lesions would a tape prep test be used for?
- Dry crusted lesions, yeast, ectoparasites
- Good for demodex, Cheyletiella, and fleas
What is the difference in appearance of keratocytes vs corneocytes on cytology?
- Keratocytes are nucleated
- Corneocytes are anucleated (from stratum corneum)
List the indications for doing a culture and sensitivity on a skin lesion
- When empirical tx has failed
- Cytology shows rod shaped bacT
- If MRSA/MRSP is suspected
A cat comes in itching with alopecia of the tail base and inner thighs. You comb the area and see flea dirt. How do you treat?
- Treat ALL PETS IN THE HOUSE with Isoxazolines, Fipronil, Imidacloprid, or Selamectin
- Clean and treat the indoor and outdoor environments
How can you diagnose sucking or chewing lice?
- Trichoscopy = Louse eggs have an operculum
- Skin scrape
- Tape prep
List the 3 different variants of Demodex
- Demodez canis
- Demodex injai
- Demodex cornei
Which of the following ectoparasites is associated with greasy skin?
A. Demodez canis
B. Demodex injai
C. Demodex cornei
D. Sarcoptic mange
B. Demodex injai
Characterize the lesions seen with localized demodex
- Lesions around the eyes, muzzle, limbs or trunk
- NON-pruritic with erythema, scaling, +/- alopecia
- Usually in younger dogs
- Usually self limiting, resolves without treatment
Characterize the lesions seen with generalized demodex
- > 5 patches
- Comodones
- Hyperpigmentation “blueish tinge”
- Peripheral lymphadenopathy
- CS of underlying systemic disease like Cushings, diabetes or neoplasia
- Pododemodicosis (painful feet)
What dog breeds are predisposed to getting juvenile onset Demodicosis?
- Pugs
- Terriers
- Bulldogs
- Westies
(In animals < 18 months of age)
What is seborrhea oleosa?
- Altered activity of Demodex injai which lives in sebaceous glands, causing oily, greasy skin
(Seen in terriers)
What variants of Demodex affect cats?
- Demodex cati
- Demodex gatoi
What needs to be known about Demodex gatoi?
- CONTAGIOUS demodex spp in cats
- Not a commensal
- Found in the stratum corneum
- Associated with allergy in cats
- Problem in multi cat households
- Commonly see overgrooming, alopecia and scaling
Which demodex spp in cats and dogs require a superficial vs a deep skin scrape?
Deep: D. canis, D. injai, D. cati
Superficial: D. gatoi
What is the treatment protocol for demodex in cats and dogs?
- Benign neglect for the localized form (resolves on its own)
- Isoxazolines for the generalized form
- Treat until 2 negative skin scrapes obtained 2 weeks apart
- Treat all cats in the house only if suspect D. gatoi
- Treat underlying disease if adult onset
What is the causative agent of mange in dogs?
- Sarcoptes scabiei
- Contagious mite living in the stratum corneum
How do you diagnose mange in dogs?
- Positive pinnal-pedal reflex
- ACUTE onset pruritis, VERY ITCHY
- Papules, scaling, yellowish crusts
- DEEP skin scrape
What is the treatment of choice for management of mange in dogs and cats?
- Isoxazolines
- Must TREAT ALL PETS IN THE HOUSE
- Must treat the environment
(very contagious)
What is the causative agent of mange in cats?
- Notoderes cati
- Contagious mite of cats
Clinical signs and presenting lesions that can be found in a cat with notoderes cati?
- Lesions on the Head and Neck
- Intense pruritis, scaling, alopecia
- THICK crusting
- Excoriations
Clinical signs and presenting lesions that can be found with Cheyletiella?
- Scaling on the DORSUM
- Severe dandruff
- Pruritis, scaling, papular rash
Which ectoparasite in dogs and cats has the pathognomonic sign of brown granular debris in the ear canal?
Otodectes cyanotis - contagious ear mite
What is the treatment of choice for management of Otodectes cyanotis in dogs and cats?
- Selamectin (Revolution) or Moxidectin (Advantage Multi)
- Must TREAT ALL PETS IN THE HOME
Contagious!!!
You are examining a cat who has been itching at their ears. You look in Henry’s pocket and see orange specks. What is the causative agent?
- Harvest mite / Neotrombicula
(usually self limiting)
What clinical signs and presenting skin lesions can be seen with Lynxacarus radovsky?
- MILD pruritis with salt and pepper mites on a dull coat
(Cat fur mite)
What is a follicular cast?
accumulation of serum and keratin adhering to surrounding hairs
Which of the following ectoparasites is not zoonotic or contagious to other animals?
A. Sarcoptic mange
B. Cheyletiella
C. Demodicosis
C. Demodex
Exception: D. gatoi
Another Exception: transferred from mom to baby only for 1st 72 hours
Which of the following ectoparasites causes the most severe pruritis?
A. Sarcoptic mange
B. Cheyletiella
C. Demodicosis
A. Sarcoptic mange