Pruritic Patient Flashcards
Definition of pruritus
unpleasant sensation in the skin that produces the desire to scratch
Scratching provides temporary relief but can lead to what?
skin damage and release of further inflammatory mediators
While dogs are often obvious about being itchy, cats may only show what?
excessive grooming (licking) – can lead to hair loss
If more than one condition is present, pruritus can be additive. True or false?
true
what are the major categories of pruritus (PAIN)
P = parasites A= allergic disease I = infections and immune mediated N = neurogenic and neoplastic diseases
What are the 8 major differential diagnoses for pruritus
- sarcoptic mange
- flea exposure +/- hypersensitivity
- pediculosis (lice)
- cheyletiella
- atopic dermatitis
- cutaneous food adverse reaction
- other external or internal parasites
- Malassezia dermatitis
which mite causes sarcoptic mange
sarcoptes scabei (burrowing)
3 characteristics of sarcoptic mange
contagious, zoonotic, intense pruritus
what reflex is present in 75-90% of sarcoptic mange cases
positive pinnal-pedal reflex
although the skin can often appear normal in sarcoptic mange cases, what type of lesions are very common
scaly erythematous papules
what pattern of distribution is seen with sarcoptic mange
ventral abdomen and thorax, feet, face, elbows and ear margins
which locations of infection are unique to sarcoptic mange (not seen in other allergic diseases)
elbows and ear margins
how is a definitive diagnosis of sarcoptic mange achieved
by finding mites or eggs on skin scrapings
why are at least 5 skin scrapings from pruritic areas necessary for diagnosing sarcoptes
difficult to find the mites, they may only be seen in 20% of cases… so even one mite or egg is diagnostic
what is often considered the most sensitive diagnostic test for sarcoptes
therapeutic trial
what are two treatments for sarcoptes
selamectin (revolution) or imidacloprid/moxidectin
true or false: other dogs in the home should be treated even if they don’t show clinical signs
true
how long can sarcoptes survive in the environment
6 days – may need to consider environment cleaning
which type of flea is most common to infest both cats and dogs worldwide
ctenocephalides felis
life cycle of the flea
adult life on the host, lays eggs eggs fall off and finish life cycle in the environment (3 larval stages and 1 pupal stage)
what two factors are required for flea development in environment
mild ambient temperatures and moderate humidity
which tapeworm is the flea an intermediate host for
dipylidium caninum
what can the flea act as a vector for
Bartonella sp., rickettsia sp. and hemoplasma
distribution of flea induced pruritus
lumbar inguinal and tail areas and thighs
clinical signs of flea infestation depend on what
whether animal is fleabite hypersensitive or not
clinical signs of a flea bite hypersensitive dog
severe pruritis in dorsocaudal area
clinical signs of a flea bite hypersensitive cat can manifest as pruritus and what 3 other signs
miliary dermatits, symmetrical self-induced alopecia and lesions of eosinophilic granuloma complex
diagnosis of flea infestation is made by
parting the hair or using a flea comb to observe fleas; may also observe flea dirt
how is “black peppery debris” confirmed to be flea feces
turns red when wet (dried blood)
topical insecticides for the treatment of adult fleas
selamectin and imidacloprid
oral insecticides for treatment of adult fleas
fluralaner (bravecto) and spinosad (comfortis)
what is in some canine products that is toxic to cats
permethrins
what products can be used to help eliminate fleas from the home more rapidly
insect development inhibitors (IDI) and insect growth regulators (IGR)
what do insect development inhibitors do
prevent normal development – prevents eggs from becoming viable
what do insect growth regulators do
mimic insect juvenile hormone (keep form developing into adult)
example of an oral IDI
lufenuron (Program)
example of an IGR
pyriproxifen (Advantage 2)
what does pediculosis refer to
lice infestation
life cycle of lice
14-21 d life cycle; only survive a few days off the host
anoplura refers to what kind of lice
sucking lice
mallophaga refers to what kind of lice
biting lice
linognathus setosus infests what animal
sucking louse of dogs
trichodectes canis infests what animal
biting louse of dogs
felicola subrostratuas infests what animal
biting louse of cats
distribution of lice
concentrate around body openings and ears… but can be found anywhere
what type of anti-parasiticide are lice very sensitive to
topical flea control products
how are lice diagnosed
by finding nits on hair shafts (cemented on) or by seeing the lice
what two methods are useful for finding nits
trichograms and clear tape preparations
treatment of lice
topical flea control product, repeat in 3-4 weeks, wash bedding and treat in contact animals
which animals do cheyletiella mites infest
dogs, cats, rabbits, people (ZOONOTIC)
where do cheyletiella mites live
surface keratin of the epidermis
how do you differentiate cheyletiella eggs from lice nits
cheyletiella eggs are LOOSELY attached to hairs
life cycle of cheyletiella
21 days; females live greater than 10 days off host
distribution of cheyletiella
dorsal trunk most commonly
which mite is a major problem in catteries
cheyletiella
diagnosis of cheyletiella
skin scrapings, clear tape impressions and flea combs in the highly scaly animal; fecal exam in a less scaly animal
which animal can it be difficult to diagnose cheyletiella in?
the over-grooming cat
treatment of cheyletiella
selamectin or imidacloprid+moxidectin
definition of atopic dermatitis
genetically predisposed inflammatory and pruritic allergic skin disease which characteristic clinical features associated with IgE antibodies most commonly directed against environmental allergens
which four factors are involved in the pathogenesis of atopic dermatitis
- genetic factors
- barrier function
- immunologic factors
- allergens
how do genetic factors play a role in atopic dermatitis
predisposition is inherited and likely polygenic
how does barrier function play a role in atopic dermatitis
defective epidermal barrier
how do immunologic factors play a role in atopic dermatitis
circulating allergen specific IgE leading to degranulation of mast cells in skin; Langerhans’ cells; T cells
type 2 T helper cells are thought to do what in atopic dermatitis
drive the reaction against inappropriate harmless substances
type 1 T helper cells are thought to contribute to what part of atopic dermatitis
persistent inflammation
how are allergens likely absorbed in atopic dermatitis
through epidermal contact and absorption
typical onset of canine atopic dermatitis
between 6 months and 3 years of age
most consistent sign of canine atopic dermatitis
pruritus
what areas of the body are typically affected by atopic dermatitis
face, feet and ventrum; ears are often inflamed.
3 components to diagnose atopic dermatitis are:
- ruling out other skin conditions
- detailed interpretation of historical and clinical features (Favrot’s criteria)
- assessment of skin reactivity by intradermal testing or detection of IgE by allergen specific IgE testing
Minimum data base to rule out other skin diseases in a pruritic patient
ectoparasite exam (flea exam, deep and superficial skin scraping, trichogram, clear tape preps treatment trial), skin cytology, +/- fungal culture
8 components of Favrot’s criteria for canine atopic dermatitis
- age of onset
how many components of Favrot’s criteria should be met to be “diagnostic” of atopic dermatitis
5 out of 8
can Favrot’s criteria differentiate food induced and nonfood induced atopic dermatitis
no
Criteria for feline nonflea-induced hypersensitivty dermatitis
- presence of at least 2 body sites affected
- presence of at least 2 of: symmetrical alopecia, miliary dermatitis, eosinophilic dermatitis, head and neck erosions/ulcerations
- presence of symmetrical alopecia
- presence of any lesions on lips
- presence of erosions or ulceration on chin or neck
- absence of lesions on the rump
- absence of nonsymmetrical alopecia on rump or tail
- absence of nodules or tumors
allergy tests do not truly identify a patient as having AD, but instead identify
offending allergens for avoidance or immunotherapy
true or false: allergy tests are useful for identifying food allergens
false
two types of allergy tests
intradermal allergy testing and serum IgE testing
which allergy test is considered gold standard
intradermal allergy test
what does the intradermal allergy test detect
cell-bound allergen specific IgE in the skin
what does serum IgE test for
allergen specific IgE levels in the blood
advantages of serum IgE
convenience and widespread availability… different labs may have different results though
are there drug withdrawals for serum IgE
no. some labs recommend withdrawal of corticosteroids though
drug withdrawals for intradermal allergen testing
withdraw oral, topic and long acting injectable corticosteroids; also withdraw oral antihistamines
two primary reasons for using allergy tests
to identify allergens that can be avoided and to allow for formulation for allergen-specific immunotherapy (ASIT)
5 components of treating AD
- treat pruritus and inflammation
- treat and prevent secondary infections
- modify immune response (ASIT)
- improve permeability barrier
- eliminate or avoid allergens
what four types of drugs are used to treat inflammation and pruritus in AD
corticosteroids, oclacitinib, antihistamines and calcineurin inhibitors
how quickly do corticosteroids work against pruritus in AD
very rapidly
3 common corticosteroids used
prednisone, prednisolone and methylprednisolone
what are side effects of corticosteroids related to
dose
what are 3 common side effects of corticosteroids
PU/PD/PP
what are some differences regarding treating cats with corticosteroids
cats require higher dosages, prednisolone rather than prednisone and some may respond better to dexamethasone
are long acting injectable corticosteroids useful in treating AD
no (rare exceptions)
what risks are associated with long acting injectable corticosteroids
diabetes, UTI and in cat, life threatening cardiac effects
example of a calcineurin inhibitor
cyclosporine (atopica)
how quickly does cyclosporine work on pruritus
slower acting; may require a month
when would you rather use a corticosteroid than cyclosporine
in acute flareups
when would you rather use cyclosporine than a corticosteroid
when you need more chronic use
most common adverse effects of cyclosporine
vomiting and diarrhea
what is associated with chronic use of cyclosporine
gingivial hyperplasia
what should you test cats for prior to using cyclosporine
FIV and FeLV
what is topical tacrolimus
a calcineurin inhibitor
what is oclacitinib (apoquel)
a janus kinase inhibitor (JAK)
what is oclacitinib used for
treatment or control of pruritus associated with allergic dermatitis and control/treatment of AD in dogs 12 months of age or older
benefit of oclacitinib
rapid antipruritic effect
what is long term oclacitinib associated with
development of UTI, vomiting, otitis, pyoderma and diarrhea…. but in 5-10% of dogs so pretty rare
where do antihistamines work
for treatment of mild skin lesions or in combination with corticosteroids
which two antihistamines work
hydroxyzine and cetirizine
vanectyl-P contains what
trimeprazine and prednisolone
how does shampooing help atopic dogs
removing allergens, physically soothing skin, and reducing secondary infections
what infections are commonly seen with AD
skin and ear infections
what do some AD dogs develop a hypersensitivity to
malassezia or staphylococcus
what can be useful for patients presenting with pruritus and recurring infections
antimicrobial shampoo
types of antimicrobial topical products
chlorhexidine shampoo, benzoyl peroxide shampoo, mupirocin, fucidic acid
antifungal shampoos
micoconazole, ketoconazole, enilconazole
what is allergen-specific immunotherapy (ASIT)
practice of administering gradually increasing quantities of an allergen extract to an allergic subject to ameliorate the signs associated with subsequent exposure to causative allergen
how can ASIT be administered
subcutaneous injection or oral
when is improvement expected with ASIT
in 6-9 months… may take a year
why should ASIT be given for life?
permanent remissions are uncommon
side effects of ASIT
rare but most common is increased pruritus
benefit of ASIT
only treatment that has the potential to bring about a cure or long-term remission
methods to improve the permeability barrier
essential fatty acids and topical lipid formulations
how does omega-3 FA work
directing fatty acid metabolism towards the production of less inflammatory eicosanoids
how does omega-6 work (linoleic acid)
important for epidermal lipid barrier
two benefits of EFA
direct FA metabolism towards less inflammatory eicosanoids and improve epidermal lipid barrier function
methods to eliminate/avoid allergens
washing bedding weekly, remove wool, frequent bathing/rinsing
most common allergen for dogs with AD
house dust mite allergen
definition of adverse food reactions
repeatable adverse reactions to specific dietary components that respond to exclusion of causative agent
difference between food allergy and food intolerance
food allergy is immune mediated
GI signs seen with food allergies
diarrhea, vomiting, flatulence, increased number of stools per day
most common distribution of food allergy pruritus
perianal region and ears
diagnosis of food AD
very strict hypoallergenic diet trial lasting a minimum of 8 weeks
most common allergens for dogs with food induced AD
beef, dairy and wheat
most common allergens for cats with food induced AD
beef dairy and fish
how do hydrolyzed protein diets work
proteins are smaller than the typical size required by the immune system to mount an IgE-triggered reaction
most common location of malassezia
face and feet
diagnosis of malassezia
skin surface cytology
what should you think of first with pinnal-pedal reflex
sarcoptes
what should you think of first with lesions on ear margins, elbows and hocks
sarcoptes
what should you think of first with perianal pruritus
adverse food reaction/food induced AD
what should you think of first with GI signs and pruritus –
food induced AD
what should you think of first with “Below the Belt” pruritus
flea allergy dermatitis
what should you think of first with blepharitis, conjunctivitis, sneezing and reverse sneezing
atopic dermatitis
what should you think of first with pruritus of the dorsal trunk and scaling
cheyletiella
what should you think of first with brown discoloration of skin (especially in the interdigital region)
malassezia
