Dermatology Flashcards
triggers for pruritus
ectoparasites
atopic dermatitis - mite proteins, pollens, moulds, microbes
food - hypersenstivity
contact allergens
drugs
atopic dermatitis pathogenesis
inherited disposition to develop type 1 hypersensitivity
predisposition to epidermal barrier defects
cytokines - bind to antigens and trigger pruritic and inflammatory porcesses
t helper cells - produce IgE to allergen - sensitisation to future exposures
Mast cells - degranulate and release histamine and heparin
JAK pathways - IL31 released by th2 cells, bind to receptors on neuronal cells, neuronal signal to brain to trigger itch perception (direct nerve stimulation bypassing mast cell process) - won’t respond to intradermal allergy test
glucocorticoids for pruritis - options
prednisolone, methyprednisolone
oral - effects in 10-30 mins after adminstration - daily dose then reduce to lowest effective dose
parenteral - rapid or slow absorption - effects last a few days for rapid and a few weeks for slower
injectable - longer acting (6-8) weeks but higher risk of HPA axis suppression, poorer dose control
topical - for pruritus in small area or short term treatment (wear gloves), may also contain antibiotic
hydorcortisone aceponate - spray, converted to more potent steroid in skin but less systemic absorption and less skin thinning, licensed to 7 days
glucocorticoids for pruritis - method of action
bypass cell membranes to bind to high affinity glucocorticoid receptors in cytoplasm (all cells)
migrate to nucleus and induce transcription of anti-inflammatory proteins
decreased production of inflammatory cytokines, enzymes and receptors
glucocorticoids for pruritis - side effects
dose dependent side effects
immune suppression - only want anti-inflammatory doses - increased infection risk
short term - PUPD, polyphagia, panting
liver problems
bladder infections
skin - thinning, pyoderma, calcinosis cutis
suppression of HPA axis - reliance –> addisonian crisis (taper, never stop suddenly)
diabetes mellitus
muscle wasting
gastric ulcer
hair loss
glucocorticoids for pruritis - when to use
severe flare up - short term
seasonal allergies
when other treatment options tried and not working
financial constraints
ciclosporin - method of action
calcineurin inhibitor - calcineurin mediated release of cytokines and histamine
enters t lymphocytes and binds cyclophilin A
inhibits function to inhibit calcineurin mediated release of cytokines and histamine
stops inflammation before it starts
slower to effect than steroids - 4-8 weeks to full effect, 8 weeks minimum trial advised before giving up
ciclosporin - forms available
atopica - oral capsule for cats and dogs
liquid oral version for cats
tacrolismus - topical - unlicensed in small animals, hard to get and epxnsive. But minimal side effects and can be helpful in small hairless areas
ciclosporin - side effects
immunosuppression - may effect function of other t cells - avoid for 2 weeks either side of live vaccination
some diarrhoea, musea, vomiting, anorexia - usually settles quickly but if doesn’t then won’t at all - GI tolerance sometimes better with food
less side effects than steroids
ciclosporin - contraindications
not in dogs <6months or <2kg
not in breeding, pregnant or lactating dogs
not in animals with history of malignant disroders - suppression of t cells needed to supress neoplasia, doesn’t cause cancer but can increase incidence of clinically apparent neoplasoa
not in diabetics - may affect ciculating insulin
care in renal insufficiency
not with drugs affecting CYP450 pathway - can affect bioavailability
cats - test for FeLV, FIV and toxoplasmosis, when treating keep inside or make it hard for them to hunt (closing in, bells) - avoid chance of getting toxo - more likely to develop signs of toxoplasmosis if infected
apoquel (oclactinab) - method of action
rapid onset (24 hours - 1 week)
JAK inhibitor - inhibitis JAK1 and JAK3 to inhibit IL31
prevents direct nerve stimulation of nerves causing pruritis
doesn’t need tapering
if using long term then monitor (less data) - yearly hematology and biochem
can be used with intradermal testing - doesn’t interfere with IgE
apoquel (oclactimab) - contraindications and side effects
not many side effects - occassional nausea and diarrhoea
not in dogs under 1 year old
not if immunosuppressed
not if history of malignant neoplasia
not if pregnant, lactating or in breeding males (untested)
long term - yearly testing (haematology and biochem)
Cytopoint (lokivetmab) - mechanism of action
IL31 caninised monoclonal antibody
mimic response to disease
highly selective antibodies, bind to IL31
prevents IL31 extracellularly and prevents binding to receptor
prevents downstream process
cytopoint (lokivetmab) - benefits and contraindications
limited impact on normal immune function
eliminated via normal protein elimination pathways like own antibodies - broken down by lysosome into amino acids that are utilised elsewhere (limited renal or hepatic involvement)
long half life - injection every 28 days
fast acting - 8 hours, full efficacy 1-3 days
can be used with concurrent disease, and alongside vaccinations
only dogs - caninised so would act as foreign body in other species
not tested in dogs under 3kgs
Antihistamines - mechanism of action
blocks histamine receptors
prevents histamine release
slight sedative effect so may just be not itching because drowsy
not much better effect proved than placebo
Antihistamines - other points
cats may be more likely to get hurt if drowsy out and about
try one for a few weeks before switching
none licensed in animals
may allow reduced dosage of other drugs
other therapies to use in combination for pruritus
essential fatty acids - improved skin barrier function (2-3 months to efficacy, need to build up)
allergen specific immunotherapy
medicated shampoos - 1-2x weekly, adequate contact time - anti-infective anti-inflammatory, moisture adding
physical prevention of self trauma - buster collars, body suits, monitoring
horse dermatological exam - nature of lesions
nature and distribution
extent/severity
changes with treatment
pruritus or pain
state of coat
feel as well as see
do exam in good light - outside not in dark stable
causes of pruritus - equine - lice
common
young or geriatric
grouped in barns
long coats
not groomed so often
very itchy
very contagious
spread by direct contact
host specific obligate parasite but can live on rugs for a while
tail and mane
moth eaten appearance
hair loss
visible lice (magnifying glass)
self trauma from pruritus
topical treatment wash - clip first
treat all horses, not just itching ones
causes of pruritus - equine - allergic skin disease
hypersensitivies - sweet itch + other, food, equine atopy
novel exclusion diet to distinguish between food allergy and atopy
lucerne nuts or timothy hay for 4-6 weeks then gradual reintroduction
Sweet itch
culicoides hypersensitivity
warm, moist areas - midges
manage midge exposure - keep in at dusk and dawn, away from bodies of water, full body rugs, netting in stables, fans in stables
lesions over tailhead and neck - bald patches
hyperkeratosis for rubbing
oozing or bleeding]secondary bacterial infection
abnormal behaviour - discomfort
usually presents around 3-4 years old or after location change
geritable component
diagnosis - clinical signs and seasonality, response to management, serology and intradermal testing (low sensitivity and specificity)
treatment - prevent exposure, shampoo to soothe skin and repair barrier, manage itching and secondary infections
sweet itch therapies
benzyl benzoate and permetrhin - reduce how often midges land
anti-inflammatories - corticosteroids - hydrocortisone, triamcinlone, betametasone
antihistamines - hydroxyzine hydropchloride - human tablets, horses need a lot
systemic injection - ringworm vaccine before midge season (mostly anecdotal)
urticaria - equine
common
lots of lumps
multiple causes - allergy, bites/stings/snake bites, infection, infestation, drug reaction, vaccines, plants, transfusion reaction, vasculitis
doesn’t tend to bother the horse but could be itchy and make riding uncomfortable depending on positioning
can go away on their own - there and gone in 24 hours
H1 antihistamine receptor blockers or centrally acting tricyclic drugs
if doesn’t go away with treatment then may need biopsy
if chronic need to find cause
urticaria - equine - ddx
dermatophyte infection - eliminate with fingal PCR
insect bites
erythema multiforme
contact hypersensitivity
infectious and immune mediated disease
paster dermatitis (mud fever) - equine
predisposing, primary and perpetuating factors
secondary to damage to skin barrier - allow bacteria in
moisture from wet mud, sweat, mites, photosensitisation, disruption to immune system
could be secondary to systemic disease - eg photosensitisation from liver disease
common on white legs and with more feathers (draught horses)
often long standing cases so not obvious cause
oedema
erythema
scaling, exudate, matting/crusting
very painful on palpation
bacterial swabs
hair brushings
skin scrapes
skin biopsy
management - pastern dermatitis
identify cuase
keep skin clean and dry and out of wet mud
cut feathers on legs
keep white areas covered if photosensitisation
clip affected area
bathe with antiseptic shampoo
rinse and dry thoroughly
remove crusts and scabs
antibacterial or corticosteroid treatment
may need to sedate - very uncomfortable
antifungal treatment - equine
lime sulphur dips
localised dermatophytes and mites
antibacterial (topical) treatment - equine
silver sulphadiazine
antibacterial (systemic) treatment - equine
culture and sensitivity
feather mite treatment - equine
dectomax injection
immune mediate condition treatment - equine
topical or oral steroids
eosinophilic granuloma - equine
not itchy
chest wall and back - maybe from pressure from tack
unsure on cause
can occasionally open and release serum or cream coloured granular material - can calicify
not painful or uncomfortable
confirm with punch biopsy (probably wouldnt bother)
can remove or treat with steroids but theu’ll come back and aren’t a welfare issue
eosinophilic granuloma ddx - equine
dermoid cysts
insect bites - would usually go down and have associated oedema
sarcoids - usually show change in keratin surface
pruritus indications in exotics
fish - flashing
primates - compulsive hair plucking
birds - feather plucking
reptiles - increased bathing
lesion distributions - pruritic skin diseases
sarcoptes scabeii - axilla, groin, hock
demodex - face, ear, feet
cheyletiella - dorsal
fleas - lumbosacral
harvest mites - between digits and ear folds
atopic dermatitis - front feet and pinna
contact dermatitis - dependant surfaces
ectoparasite testing
coat brushing - fleas/flea dirt, cheyletiella
hair pluck - demodex, hair trauma
tape strip - cheyletiella, harvest mites, cytology
skin scrape - demodex, sarcoptes (low sensitivity)
sarcoptes IgG - sarcoptes (exposure, not necessarily infection)
treatment - flea allergy dermatitis
manage pruritus
treat animal and in contact animals
treat environment
ongoing flea management
treatment - demodex
dogs and hamsters (most common hamster mite)
usually self limiting
amitraz shampoo (in well ventilated area - breathing problems in people)
macrocyclic lactones - eg bravecto
treatment - sarcoptic mange
macrocyclic lactones (bravecto)
fipronil in young animals
keep away from foxes
treatment - cheyletiella
rabbits - walking dandruff
most spot ons effective (but not licensed)
ivermectin in rabbits
fipronil in other species
treat environment
treatment - harvest mites
fipronil on affected area
treatment - traxicarus caviae
guinea pigs
intense itching –> seizures (can be triggered by handlign)
benzodiazepines to sedate
ivermectin to treat
treatment - ophionyssus natricis
snakes
most common snake ectoparasite
vector for viral infection
permetrin, ivermectin or fibronil
treat environment
rub on snake
careful of ventilation - alcohol in formultions
treatment - knemidocoptes
birds
scaly leg/scaly face
demetiaceous earth bath (or ivermectin, but not in food producing animals)
treatment - red mite
chickens
out at night
throw out coop
demetiaceous earth or fluralaner
testing - infectious skin disease
tape strip cytology - stained - dry skin lesions and skin folds
impression smear cytology - moist and ulcerative lesions - pyoderma shows bacteria with phagocytosing neutrophils, presence of rods indicates culture and sensitivity
culture and sensitivity - if rods on cytology
woods lamp - fungal disease - false positives and false negatives
dermatophyte culture - long culture time, in house or external
treatment - bacterial overgrowth
topical
shampoo, mousse, wipes - chlorhexidine
treatment - surface pyoderma
top layer only - erosions and ulcers
usually secondary
stop licking and scratching
topical
clip for better access
clean with saline and syringe
avoid chlorhexidine - may cause reaction
NSAIDs or topical steroid cream for analgesia and stopping inflammation
systemic treatment if no improvement over 2 weeks
treatment - hot spots/acute moist dermatitis (pyotraumatic dermatitis)
worse in warm weather
can progress to deep pyoderma if scratched
flystrike in long haired animals
clip and clean for exam
treat based on how deep you think it is
treatment - superficial pyoderma
pustules - usually pop
may need systemic antibiotics - amoxiclav, cliomycin
treatment - deep pyoderma
infection involves dermal tissue
furunculosis - deep with destruction of hair follicle
systemic antibiotics
analgesia
topical treatment
apoquel
painful
treatment - skin fold pyoderma
treat as superficial pyoderma
treatment - bacterial folliculitis
only affecting follicles
moth eaten looking
treat as superficial
treatment - feline acne
idiopathic keratinisation - usually on chin
secondary infections
wash to remove excess keratin
treat like superficial
treatment - eosinophilic granuloma complex
hypersensitivity in cats
ulcer, eosinophilic plaque or collagenolytic granuloma
not itchy until secondary infection
steroids for underlying immune issue
management for pyoderma
treatment - fungal disease
yeast overgrowth (dogs) - usually secondary infection, smells - topical antifungal or chlorhexidine shampoos
dermatophytosis (cats and small animals) - check owners aren’t itchy too, clipping, topical shampoos or rinses (microconazole or chlorhexidine)
allergen testing
not diagnostic of allergic disease
unreliable for diet
intradermal testing - gold standard - not often done because owners don’t like it
serological testing - easier and owners prefer it
cutaneous food allergy
any non seasonal pruritus
serology no good
food trial - correct pyoderma first
diet history - including treats, flavoured medications and toothpastes
ongoing exclusion diet and symptomatic management of flare ups
cutaneous food allergy - diet options
hydrolysed - best, varying degrees of hydrolysis
limited antigen - most hypoallergenic pet shop foods, pick novel protein and carb based on diet history
home cooked - not usually well done
trial for 6-8 weeks
contact dermatitis
irritant or allergic
check mouth in cats
irritant more common
treatment - remove irritant + supportive care
allergic - type 4 hypersensitivity - sparsely haired skin areas in contact with allergen
treatment - remove allergen, supportive care (steroids)
atopic dermatitis
dogs
diagnosis of exclusion
usually - <3yo, indoors, responsive to steroids, unaffected dorsolumbar area
usually dust mites or pollen
management not cure
atopy definition
genetic disposition to inflammatory and pruritic skin disease
pruritic threshold
amount of itchy stimuli that can be tolerated before becomes pruritic
flare factors - atopic dermatitis
stress - especially cats
seasonal - pollen, weather
infection - more likely to develop bacteria or fungus build up because skin barrier compromised
ectoparasites
allergen concentration
central heating - dries skin
client and patient factors - atopic dermatitis
finance
time
transport
handling
atopic dermatitis - treatment
allergen avoidance as much as possible - smooth floors, insecticides, keeping out of long grasses
anti pruritics
topical treatment - control bacterial and yeast levels, soothe skin, improve barrier function
chlorhexidine
oatmeal, tea tree - emoliants
salicyclic acid - exfoliant
mousses and foams for when don’t like bathing
immunotherapy - based on allergen testing
supplements - EFAs, bioactive lipis, probiotics, vitmain E, vitamine D
pemphigus foliaceus
uncommon
autoimmune
pustules and vesicles
corticosteroid treatment
cutaneous lymphoma
mostly hamsters
biopsy for diagnosis
secondary infections
treat with steroids
signs - acute otitis externa
pinna - redness, trauma from scratching
canal - redness, swelling, vasodilation, cerumen, pain
signs - chronic otitis externa
pinna - redness, swelling, scaling, crusting, alpopecia, hypermigmentation and lichenification
canal - brown exudate, hyperplasia, stenosis
aural hematoma causes
secondary to otitis externa - excessive head shaking
signs - otitis media
head tilt
progression to vestibular syndrome - nystagmus, strabismus, vomiting
horners and facial nerve paralysis
concurrent otitis externa except rabbits
signs - otitis interna
vestibular syndrome - loss of balance, ataxia, vomiting
lethargy
depression
unilateral deafness
clinical exam - ears
signs of skin disease - atopic dermatitis
assess for -
Foreign bodies
Parasites – otodectes (dogs and cats), ceroptes (rabbit)
Discharge – characterise it
Degree of stenosis
Ear canal patency
Look at tympanic membrane – perforation?
Neoplasms or polyps
membrane rupture - before putting anything in
smallest tip size - can be painful
remove foreign bodies if poss
neuro exam
cytology - ears
differentiate bacteria and yeast
rods - send for sulture
biofilms and inflammatory exudates
culture and sensitivity - ears
before antibiotics
always if rods
concentrations of ear preparations usually higher than the ones tested so if just a bit resistant may still be effective
imaging - ears
chronic cases or if ear too stenotic to look down
plan surgical intervention
radiography - poor sensitivity
CT - best for otitis media
MRI - best for otitis interna
systemic treatment - ears
ivermectin - psoroptes
selamectin and moxidectin - otodectes
systemic antibiotics/antifungal s- mostly in media or interna
treat secondary infections
managing infalmmation - topical steroids unless ruptured membranes
analgesia
surgical flushing - interna
ear cleaners
always useful
remove debris - gives better access for medical treatments
break down biofilms
help effect of anti microbials (trisEDTA)
wait an hour before topical medications
make sure using one that’s safe with ruptured membrane
initial clean may need sedation - painful
topical treatment - ears
topical steroids - unless ruptured membrane
rods - aminoglycosides and ploymixin B, fluoroquinolones if not effective
trisEDTA - improve antibiotic action
aural hematoma treatment
drain and flush with saline then give steroids - high failure rate
steroids either direct into hematoma or systemic
treat underlying otitis
surgery - s shaped incision then clean out hematoma and flush with saline, suture sides back together, can put in drain for while healing
surgical ear treatments
lateral wall resection - opens ear to let more oxygen through, control anaerobic bacterial growth
total or partial ear canal ablation (TECA) - remove ear canal - complications include necrosis, keratosis, pharyngeal swelling, facial nerve paralysis and others
lateral and ventral bulla osteotomy (LBO) - usually with TECA, reduces complication rate. need to remove all epithelium or will keep producing fluid. care with facial nerve
PECA + LBO - rabbit middle ear disease with concurrent dental disease resistant to conservative managment. bulla can be left open for flushing or antiboitic impregnated beads can be put in
anal gland disease - signs
scooting
licking, chewing, over grooming
fishy smell
+/- anal discharge
reluctance to sit or poo
straining
erythema or swelling - infection
abscess - late stage (early in skunks)
cytology - anal glands
not very useful, all sorts of bacteria etc there as normal
culture - anal glands
not very useful, healthy and diseased look very similar
anal gland impaction
most common
full glands on palpation
no change in secretion
no signs of infection or inflammation
if untreated –> saculitis or abscessation
squeeze glands out
manage weight
increase dietary fibre
control underlying disease
fecal impaction
guinea pigs - older intact males
secondary infection and pain
routine management by owners
anal sacculitis
usually secondary to impaction - inflammation and infection
pain
erythema
welling
may need sedation to empty anal glands
flush at same time - saline or ear drop preparations
systemic NSAIDs
antibiotics if abscessation
anal abscessation
usually when anal gland rupture - may form fistula
if no fistula may need to form one to drain
flushing
topical treatment
NSAIDs
systemic antibiotics
anal sacculectomy if not responding or chronic
anal sacculectomy - open vs closed
open - anal gland incised to remove secretory lining - lower risk but less effective
closed - whole gland out - more risk of nerve damage to external anal sphincter
anal gland furunculosis
german shepherds
immune mediated inflammation
distinctive
ulveration and sinus tracts
may communicate with rectal lumen
pain
licking
abnormal tail carriage
increased frequency of small amounts of feces
high anti-staph IgG titre
anal gland furunculosis - treatment
surgery - resection, cryosurgery, laser - high risk of complications
medical - preferred - immunomodulatory therapy, treat secondary infections, analgesia, supportive care
ciclosporin - 80% remission
topical tacrilimus - cream, may not like it if painful
preds - low success rate
secondary infection - TMPS and amoyclav
analgesia - NSAIDs and opioids (very painful, need multimodal)
supportive care - stool softeners
anal gland neoplasia
apocrine gland carcinoma - most common
locally invasive and metastatic
paraneoplastic hypercalcemia - stabilise this before surgery
spread to sublumbar lymph nodes
diagnosis - biopsy, fna often inconclusive, radiograph for mets, CT for surgical planning
treatment -
chemo - prior to surgery to shrink
radiotherapy - improve prognosis post surgery
surgical removal
guarded prognosis - influenced by stage. rule of thumb is 12 months if there’s mets a point of surgery
causes of non-pruritic alopecia
cushings - symmetrical flank with rat tail
hypothyroidism - flank alopecia with hyperpigmentation
hyperoestrogenism - ferrets
hyperadrenocorticism - ferrets - neutered jills and hobs
trichogram
broken hairs - self-trauma - pruritic
telogen hairs - more abundant in endocrine issues
clumped melanin - colour dilution alopecia
alopecia X
cosmetic alopecia
diagnosis of exclusion
treatments -
neutrering
melatonin
benign neglect
get it a jumper
Sheep Scab (psoroptic mange)
most important ectoparasitic disease of sheep
notifiable
legal requirement to treat infected animals and all others in flock
big economic impact
mite
entire life cycle on host - 10-14 days
viable off host for 15-17 days (environmental reservoir)
sheep scab - psoroptes ovis - pathogenesis
quiescent phase - reservoir in axilla, groin, pinna (warmer months)
highly contagious
clinical phase - inflammation with vesicles and serous exudate - hypersensitivity response
centre of lesion dries and mites multiply and move outwards
should assume whole flock is infected
sheep scab - signs
patches of lighter wool
intense pruritus - scratching on gates and fences
larger areas of skin damage
stained, ragged wool
wool loss
nibbling flanks
dullness
staying apart from flock
sheep scab - diagnosis
skin scrape - in clinical stages, can see mites
blood ELISA - testing for antibodies - as soon as 2 weeks after exposure
sheep scab - treatment
plunge or dipping (not jet spraying - will infect environment) - organophosphate
injectable parasiticide - macrocyclic lactones - some resistance developed
establish origin
contact neighbours
review fencing and contact with neighbouring fields
sheep scab - plunge dipping
need safe use of sheep dip certificate, environmental permit, container to store waste water, leak proof dipping tanks, crook and timer
do not dip on full stomach, when thirsty, when wet, or with open wounds
PPE
correct concentration should be used
immerse whole body apart from head and ears for at least 1 minute, head immersed at least twice
sheep scab - ddx
lice
keds
blowfly strike
tick infestation
scrapie - pruritus and nibble (individuals)
wool slip
ringworm
dermatophilosis
cattle ringworm
zoonosis
very common
calves
fungal
mainly trichophyton verrucosum
spread by direct or indirect contact
most recover and then have immunity
notifiable in norway - different attitude
ringworm - signs
grey scaly lesions
ring shaped
mainly head and neck
ringworm - treatment and prevention
topical antifungal sprays
vaccine available - used where large number infected to reduce severity/number of cases - vaccine related outbreak in poland
ringworm - diagnosis
microscopic examination of hair samples - spores
bovine papiloma virus - warts/angleberries
virus has a predilection for keratinocytes - penetrate minute abrasions
benign, hyperplastic lesions - warts
usually resolve over time
can become neoplastic - bladder and upper GI
potential cross species - same virus does sarcoids in horses
unsightly
sever infections or widespread lesions can lead to loss of body condition and death
teat lesions - can interfere with milking
penile fibropapilloma - issue in breeding bulls
bovine papilloma - treatment
leave to fall off naturally
surgical removal - but can regrow
vaccines - expensive
antimicrobials - for secondary infection
bovine ischemic teat necrosis
emerging disease
mostly diary heifers in first lactation
premature culling
economic loss
may be linked to digital dermatitis
primarily base of teat then extends distal or proximal
severe lesions - sloughing of teat - further complications
erysipelas - pigs
gram +ve rod bacteria
can carry - on tonsils
excrete in feces and urine
soil and surface water contaminated - environmental reservoir for several weeks
zoonotic
sudden death
usually fattening pigs - 55-80kg
scarlet flushing of skin - septicemia
erysipelas - cutaneous form
pyrexia
redding and blotching skin
purple-red diamond shaped lesions - pathognomonic
acute - can kill in 12-48 hours
anorexia and thirst in older pigs
dullness and reluctance to move
abortion in pregnant gilts/sows
erysipelas - chronic forms
valvular endocarditis - congestive heart failure, death
proliferative synovitis in joints
ear tip necrosis
polyarthritis - lameness
erysipelas - control
in soil - more in outdoors pigs
penicillin - treat early
vaccine - immunity lasts 6 months, need boosters
pityriasis rosea - false ringworm - pigs
probably genetic
usually a few per litter
lesions from 4 weeks
hyperemic patches on flanks, groin, thighs
self limiting - few months
unsightly but not pruritic
pig grows normally
