Dermatology Flashcards
what are the most common signs presented by an animal with a dermatology issue?
pruritus scale alopecia crusting ulceration erosion nodules
what can pruritus be due to?
allergy
parasites
microbial infection
ears
what type of disorders are implied when scale is present?
keratinisation disorders
what are primary skin lesions?
those that develop within the skin of their own accord
what is alopecia?
hair loss - may also be secondary
what is a bullae?
localised collection of fluid >0.5cm in diameter and larger than a vesicle
what is erythema?
a diffuse or localised redness of the skin which disappears with diascopy
what is a macule?
flat skin discolouration <1cm in diameter without surface elevation or depression
what is a nodule?
solid elevation greater than 1 cm usually extending into the dermis
what are large nodules referred to as?
masses
what is a papule?
small solid elevation of skin up to 1cm in diameter
what is a papule caused by?
infiltration of inflammatory cells, fluid or foreign material (calcium), with oedema and epidermal hyperplasia
what is a patch?
localised flat change in skin pigmentation larger than 1cm in diameter (a big macule)
what is a plaque?
flat topped elevation of the skin >0.5cm, flatter than a nodule
what is a plaque formed from?
coalition of papules
what is a pustule?
small elevation of epidermis filled with purulent material
what is a vesicle?
small elevation of the epidermis filled with clear fluid <0.5cm in diameter (blister like)
what is a wheal?
sharply raised lesion consisting of oedema, appears and disappears within minutes to hours
what are secondary lesions created by?
scratching, chewing or other trauma to the skin
what are secondary skin lesions the result of?
infections
evolve from regressing primary lesions
what is an comedone?
dilated hair follicle filled with cornified cells and sebaceous material
what is a crust?
dried exudate, cells, pus and scale adherent to the surface
what is an epidermal collarette?
excoriation / erosion, superficial damage to the epidermis
what is a fissure?
linear cleavage into the epidermis
what is hyperkeratosis?
increase in thickness in the cornified layer of the skin
when is hyperkeratosis often seen?
chronic skin disease
what is hyper and hypopigmentation?
changes in skin colour
what is lichenification?
thickening of the skin resulting in a cobblestone appearence
what is scale?
accumulation of loose fragments of the cornified layer of the skin
what is ulceration?
full thickness loss of the epidermis exposing the dermis
what is erosion?
some level of damage to the epidermis
what is involved in the process of diagnosing dermatological issues?
history
physical exam
list of viewed signs/problems
differential diagnoses which inform diagnostic plan
what is the key part of diagnosis of dermatology diseases?
history
what areas of the body are included in a dermatological physical exam?
ears (otoscope)
pads
ventrum
what questions should be asked during history taking to aid diagnosis of dermatological issues?
diet
other animals in the house
any human skin issues - zoonosis
what are the main diagnostic techniques used in dermatology?
acetate tape skin scrapings impression smears flea comb trichogram skin biopsy
what can be found during acetate tape for cytology?
malassezia
bacteria
inflammatory cells
squames
what can be found from performing deep skin scrapings?
demodex mites
what can be found from performing superficial skin scrapings?
cheyletiella
sarcoptes
what can be found by performing impression smears of skin?
inflammatory cells
malassezia
bacteria
what bacteria may be found after performing impression smears?
staphylococci
bacilli - Pseudomonas
where should be swabbed when performing an ear swab?
bottom of vertical canal
what may be found when testing with a flea comb?
fleas
cheyletiella
what is a trichogram?
hair pluck
what is anagen hair?
new growth within follicle
what is telogen hair?
resting phase of hair growth
what may be found from a trichogram?
anagen and telogen hair mite and lice eggs evidence of pruritus dermatophytosis hair shaft abnormalities
how can evidence of pruritus be seen in trichogram?
broken ends of hairs
what is dermatophytosis?
infection of hair and skin caused by dermatophytes
what may be evidence of flea infestation seen from flea combing?
flea faeces - small red spots
what breed of cats is dermatophytosis often seen in?
persian
what are the signs of dermatophytosis?
scaling
alopecia
how can dermatophytosis be diagnosed?
Wood’s lamp
microscopy
dermatophyte test medium
culture
how does a Woods lamp test for dermatophytosis work?
use UV light to check for fluorescence of bacteria on skin
what test medium is used for dermatophytosis?
lactophenol cotton blue
how long will a dermatophytosis culture take?
2 weeks at room temperature
how can dermatophytosis be treated?
topical therapy
systemic therepy
what may apparent cure of small localised lesions of dermatophytosis be due to?
hosts immune response rather than products used
where may dermatophytosis infection spread to from obvious lesions?
up to 6cm away
what effect can clipping have on dermatophytosis?
reduce environmental and host load but can spread the disease around the animal
what shampoos can be used to treat dermatophytosis?
Malaseb
Microbex
what dips can be used to treat dermatophytosis?
Imaverol
what has Malaseb been proven to help with?
decontamination of infected cats environment
how should shampoos for treatment of dermatophytosis be applied?
twice weekly and rinsed after 10 minutes
when is systemic treatment of dermatophytosis used?
for generalised, chronic infection
what systemic treatment for dermatophytosis is available in cats?
Itraconazole
how should Itraconazole be used to treat dermatophytosis?
7 days
3 x per day
7 days between each
what forms is Itraconazole available in?
suspension or capsules
what drug is used for treatment of dermatophytosis in dogs?
Ketoconazole
what is a major source of environmental contamination with dermatophytes?
fungal spores on hairs
how can dermatophytes be removed from the environment?
combination of physical cleaning and use of chemical agents
grooming equipment, collars, bedding should be thrown away
washable items should be soaked in antifungal disinfectant and then washed above 50
what is the difficulty with using chemicals to clean the environment?
staining / damage of soft furnishings
what chemicals can be used to clean the environment following dermatophyte infection of animal?
bleach (1:100 dilution)
Enilconazole - spray or smoke bomb
what are the key indications for skin biopsy?
neoplasia (suspected or obvious)
unusual or serious generalised dermatosis
condition responding poorly to therapy
other diagnostic tests not helpful
vesicles, bullae, erosions or ulcerations
what forms of anaesthetic are used for skin biopsy?
GA - most common
LA and sedation
what skin prep is necessary for biopsy?
clip but no scrub as bacteria on skin need to be preserved
what lesions should be chosen for biopsy?
multiple sites
fully developed lesions
not chronic or traumatized sites
what are the 2 main types of skin biopsy?
punch (4/6/8mm)
excision
what tests may be performed on biopsied tissue?
histopathology
culture
cytology
what are the 4 main results of a skin biopsy?
diagnostic
compatible with clinical diagnosis
not compatible with a diagnosis
non-diagnostic
what histopathologist should be chosen to deal with skin biopsies?
one with interest in skin disease
what should be provided to lab along with sample?
full history (age, breed etc)
signs
differential diagnoses
what are “flare factors”?
central and additional influences on the perception of pruritus
what are the 4 main “flare factors”?
fleas
bacterial and yeast infection
dry skin and low humidity / sweating
psychological factors (stress, anxiety)
what scale is involved in assessment of pruritus?
visual analogue scale
who will complete a VAS relating to pruritus?
owner
clinican
what should owners be specifically questioned about in relation to pruritus?
foot liking and face rubbing which may be interpreted as grooming
head shaking - not solely related to ear infection and can be a sign of generalised pruritus
why must all factors contributing to pruritus be investigated?
animal without disease manifestations may tolerate a certain allergic load - small increase may push the animal over the threshold to showing clinical signs.
naturally occuring diseases alongside pruritus may also push animals over this threshold.
There is often more than one cause
what are the clinical signs of canine atopic dermatitis?
self trauma secondary bacterial and Malessezia (yeast) infections alopecia erythema excoriation hyperpigmentation lichenification
how is canine atopic dermatitis diagnosed?
rule out other conditions that cause pruritus
what is used to select allergens for immunotherapy for canine atopic dermatitis?
intradermal injections and blood testing
what breeds of dog are particularly prone to atopic dermatitis?
GSD
Terrier
animals with lots of skin folds
what is not confirmed by allergen testing?
diagnosis of atopic disease
what can allergen testing provide?
identification of allergens of clinical significance
basis for allergen specific immunotherapy (ASIT) / immunotherapy
what are the clinical signs of pyoderma?
intraepidermal pustules easily disrupted by grooming / scratching
transient primary lesions and secondary lesions of crusting
what is produced by peripheral spread of pyoderma?
annular lesion with epidermal collarette
what aspects of pyoderma are sometimes antibiotic responsive?
lesions and sometimes the pruritus
when will pyoderma reoccur?
if underlying cause is not identified and managed
what are the common underlying causes of pyoderma?
ectoparasites
allergy
endocrinopathies
what are the 2 main types of pyoderma?
superficial
deep
what happens during superficial pyoderma?
bacteria multiply on surface of skin and in hair folicles
what happens during deep pyoderma?
infection is deep into hair follicle - often caused by demodex mite