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Pruritis - Coggle Diagram
Pruritis
Diagnosis
skin scraping
ectoparasites common
may not detect scabies, so consider anti-scabies parasiticide
demoted may not be detected, a decrease in pruritus after a trial course of weekly lime sulphur dips consistent with feline demodicosis
ectoparasite therapy trial
skin cytology
malassezia or bacterial dermatitis
intact pustules can be ruptured with a 25 gauge needle and contents smeared on slide to examine if bacteria/inflammatory cells present
dermatophyte culture
most dogs and cats with dermatophytosis are not pruritic
clinical signs include alopecia and broken hairs (also a clinical sign in most pruritic cats)
perform in dogs breeds prone to dermatophytosis e.g. yorkshire terriers
faecal exam
floatation test
dx surface dwelling ectoparasites e.g. demoted gate or cheyletiella if swallowed in grooming
endoparasites e.g. hookworm can cause prurititic dermatitis
food trial
year round pruritis
novel or hydrolysed protein
intradermal or serological allergy testing
atopic dermatitis
used to select allergens for formulation of immunotherapy
skin biopsy
if chronically self-traumatised skin with secondary skin lesions, often does not revel cause of pruritis
will not determine allergen to which patient is allergic
useful if primary skin lesions present
useful to r/o severe but uncommon pruritic dermatoses e.g. epitheliotropic lymphoma in older patient or seborrhoea
may be necessary to diagnose demodicosis in some thick skinned dogs such as shar peis
complete blood count and general biochem
if systemic condition suspected, but unlikely to identify underlying cause of pruritus
physical exam
nose to tail, including ventrum, ears, ear margins, mucocutaneous junctions, mucosa, interdigital region, claws, paw pads, axilla and inguinal area
excoriations, salivary staining, broken hairs are consistent with pruritus
dogs that chronically chew themselves may have worn incisors and canine teeth
self-induced alopecia or alopecia due to pruritic behaviour needs to be differentiated from spontaneous alopecia
chronically self traumatised skin develops...
erythema
excoriations
lichenification
alopecia
superficial pyoderma
papules
pustules
epidermal collarettes
demodicosis
comedones with alopecia
obtain deep skin scrapes
signalment and history
success of previous pruritic tx
age when pruritic begun
atopic dermatitis 6 months to 3 years
food allergy can begin at any time
marked skin folds e.g. shar peis and bulldogs develop intertrigonal dermatitis
bassett hounds have higher levels of malassezia on skin which can manifest as variable pruritus
key questions
when did the signs (licking, chewing, scratching, head shaking) begin
any history of other skin or ear conditions
how severe is pets pruritus (severe = unable to sleep through night or is pet distracted with food, play etc)
what did skin look like at beginning (primary skin lesions at onset of pruritus)
what have you used to treat pruritus
should be pets primary care giver
Treatment
glucocorticoids
a sparing effect of antihistamines and fatty acid supplementation reported, even in patients in which antihistamines and fatty acid supplementation had not improved condition on their own
adverse effects
PU/PD/PP
lethargy
exercise intolerance
muscle wasting
panting
secondary infectins
delayed wound healing
calcinosis cutis
ciclosporin
essential fatty acid supplementation
antihistamines
low success rate, but low cost and relatively safe
most effective when started prior to onset of allergen exposure and should be administered daily, rather than on an as needed basis
calcineurin inhibitors
can be used topically
tacrolimus is used primarily in patients with atopic dermatitis, esp. when use of topical glucocorticoids is contraindicated
advantages of topical tacrolimus over glucocorticoids are the lack of cutaneous atrophy and lack of negative effects on hair coat
pathophysiology
chemical mediators in skin induce skin sensation by stimulating the free nerve endings
histamine
proteases
peptides
prostaglandins
leucotrienes
opioid peptides
transmitted by non-myelinated (c) and myelinated (A-delta) fibres
if pruritic stimuli exceed a certain level, the animal will show clinical signs (threshold phenomenon)
pruritic stimuli have an additive effect on the level of pruritus --> summation of effect
Diagnostic approach in pruritic dog
examination
fleas, flea dirt
treat for fleas
papules
parasiticide trial
ectoparasite or if no response evaluate for allergies
antibiotics therapy
pruritic pyoderma
evaluate for allergies and immunosuppresion
alopecia
skin scrapings
parasiticide
erythema, debris
skin cytology
antibiotic or anti fungal therapy
history
seasonal
treat for fleas
flea allergy dermatitis or if no response allergy test
non-seasonal
food trial
food allergy/allergy testing
Diagnostic approach for pruritus in cat
examination
fleas, flea dirt
treat for fleas
papules, scaling, crust
dermatophyte culture
evaluate for allergies
treat for dermatophytosis
skin scrape
evaluate for allergies
parasiticide
no primary lesions
parasiticide and dermatophyte culture
history
seasonal
treat for fleas
allergy testing
flea allergy dermatitis
non-seasonal
food trial
allergy testing
food allergy
