Exam 2 - Pruritus Flashcards
what are the big 3 categories of disease that should be considered for a pruritic animal?
parasites, microbial, & allergies
‘what are the infections? why are they there?’
what are examples of each category when approaching a case of a pruritic animal
infections - folliculitis, yeast dermatitis, ectoparasitism
why are they there - allergy (young to middle-aged animals), endocrinopathy (middle aged to senior), cornification (young or specific breeds), anatomical
when confronted with a pruritic patient, what should you rule out first?
parasites & skin infections
what is the pathway of pruritus?
stimulus activates a mediator -> pruriceptor of afferent neuron -> peripheral pathway through the dorsal root ganglion -> central processing & modulation -> interpretation & perception -> response to itch
what are some examples of pruritogenic substances?
histamine, proteases, lipases, eicosanoids, kinins, opioids, substance P, exogenous factors from bacteria/fungi/pathogens
what is epicritic itch? what is the transmission of it through the body?
well-delineated, sharp, spontaneous itch
transmission - myelinated fast-conducting A axons
what is protopathic itch? what is the transmission of it through the body?
poorly-delineated, burning itch
transmission - polymodal nociceptor units with unmyelinated slow-conducting C axons
what is the gate control theory in regards to pruritus?
higher CNS factors may accentuate or lessen the pruritic sensation
anxiety, stress, boredom, playing, & other learned experiences influence the sensation of pruritus
why is mast cell concentration an important factor to consider in a pruritic patient?
mast cells have a higher dermal concentration in the pinnal & ventral interdigital pedal skin compared to other parts of the body - common itchy areas for animals with allergic skin disease
T/F: petting a cat against the direction of hair growth may reveal barbered hair which is highly suggestive of a self-induced injury from pruritus
true
what are some examples of feline cutaneous reaction patterns?
miliary dermatitis, self-induced alopecia, cervicofacial pruritic dermatitis, & eosinophilic granuloma complex
what is a feline cutaneous reaction pattern?
reaction patterns that aren’t diagnoses but rather lesional clues of an underlying pruritic and/or allergic disorder
what is the pruritic threshold?
level of pruritus required to elicit the sensation of pruritus - this level is different for each individual animal
what is the summation effect?
additional stimuli exacerbate & compound the sensation of prurirtus
what immediate side effects are seen with animals on glucocorticoids?
PU/PD/PP & panting
what are some cutaneous side effects associated with animals on glucocorticoids?
alopecia, hair color/texture changes, comedones, scaling, seborrhea, hyperpigmentation, thin atrophic skin, inelastic skin, poor wound healing
what are some musculoskeletal side effects associated with animals on glucocorticoids?
muscle atrophy & weakness (including intercostals & abdominal muscles -> panting & pot belly) & ruptured cruciate ligaments
what is the goal of using glucocorticoids when treating a pruritic animal?
make the animal comfortable with a humane level of itch but not to make them 100% itch-free since the risks of glucocorticoid use begins to trump the benefits of use
T/F: if your patient requires longer than 3-4 months of oral glucocorticoids to manage allergic skin disease, other treatment options should be sought out
true
what drug is FDA labeled for treating canine atopic dermatitis?
atopica - cyclosporine
what drug is FDA labeled for treating feline allergic dermatitis?
atopica for cats - cyclosporine
what drug has an FDA label for canine pruritus associated with allergic skin disease & canine atopic dermatitis?
oclacitnib - apoquel
what is lokivetmab?
cytopoint - caninized (dog-specific antibody) anti-cIL-31 monoclonal antibody (mAb) for canine allergic dermatitis & atopic dermatitis
what is the goal of allergen-specific immunotherapy (ASIT)?
reduce the intensity & severity of clinical signs along with reducing the frequency of/possible need for other therapies best avoided long-term such as glucocorticoids/cyclosporine
how does ASIT work?
ASIT retrains the immune system on how to perceive its environment
what animals is ASIT mainly reserved for?
atopic animals who are affected at least 6 months out of the year who do not tolerate symptomatic therapy or can’t receive symptomatic therapy
for canine atopic dermatitis affecting animals less than 6 months of the year, what are your absolutes you must use for treatments? what are your options?
absolutes - adulticidal flea prevention, infection control, & baths
options - cytopoint, oclacitnib, & glucocorticoids
for canine atopic dermatitis affecting animals more than 6 months of the year, what are your absolutes you must use for treatments? what are your options for animals less than 7-8 years old? what about older than 7-8 years old?
absolutes - adulticidal flea prevention, infection control, & baths
options for 7-8 y/o - cytopoint & ASIT
options for > 7-8 y/o - cytopoint, apoquel, atopica, +/- ASIT
when managing a patient with atopic dermatitis, what therapies can be used for pruritic flares?
apoquel or glucocorticoids - topical or systemic
cytopoint - given less frequently than every 4 weeks when receiving other atopic meds
what 3 drugs are you not going to use in a patient with pruritic skin disease from demodicosis?
apoqel, glucocorticoids, & cyclosporine
what skin condition is associated with this pruritic pattern/distribution? how will you work this patient up?
folliculitis - happening on haired skin - asymmetric/patchy superficial lesions
history/pattern of itch/lesions, cytology, deep skin scrapes, & DTM/PCR - need to rule out superficial pyoderma, dermatophytosis, & demodicosis
what skin condition is associated with this pruritic pattern/distribution? how will you work this patient up?
yeast dermatitis (malassezia) - lesions in body folds, seborrhea, erythema, scaling, hyperpigmentation, lichenification, alopecia
history, pattern of itch/lesions, & cytology
what do you think is happening here?
yeast dermatitis
what requirements must be met before prescribing apoquel for your patient?
demodex has been excluded & the patient is older than 1 year
____% of all dogs develop signs of food allergies by 1 year of age
40%
a positive pinnal-pedal response is fairly specific for what skin condition?
scabies
what is the pinnal-pedal reflex in dogs?
rubbing of the pinna/ear flap causes the ipsilateral hind leg to start a scratching motion
what skin condition is associated with this pruritic pattern/distribution? how will you work this patient up?
flea allergy dermatitis - lesions on caudal body, excoriation, erythema, self-induced alopecia, scaling, crusted papules, & hot spots
history, pattern of itch & lesions, +/- fleas with a flea comb, look for flea dirt, look for tapeworms, & evaluate response to therapy
what skin condition is associated with this pruritic pattern/distribution? how will you work this patient up?
sarcoptic mange - lesions seen in sparsely haired areas, severely pruritic, excoriations, erythema, self-induced alopecia, crusted papules, & scaling
history, pattern of itch/lesions, + pinnal-pedal response, do superficial skin scrapes, ELISA test, & monitor response to therapy
what is this? what does it cause?
sarcoptes scabei var. canis - sarcoptic mange
what flea is most commonly implicated in causing flea allergy dermatitis?
ctenocephalides felis
an outside dog that isn’t on any flea/tick prevention presents with this skin lesion - what do you suspect is going on?
flea allergy dermatitis
a puppy that was recently adopted from a shelter presents severely pruritic, and upon doing a superficial skin scrape, you see this bug on cytology - what do you think is going on?
sarcoptic mange
what dosing is used for oclacitnib for pruritic dogs?
0.4-0.6mg/kg by mouth every 12-24 hours
how does oclacitnib work?
inhibits the production of pruritogenic & inflammatory signals induced by IL-2, IL-4, IL-6, IL-13 (allergy & inflammation), & IL-31 (pruritus) that are dependent upon JAK1 & JAK3 enzyme activity
T/F: oclacitnib is an effective anti-pruritic that can be used during a flare up of itchiness & it can be used in a diagnostic work-up of a patient with allergic skin disease if needed
true
what dosing is used for steroids for pruritic dogs?
prednisone at 0.5-1.0mg/kg by mouth every 24 hours for 7 days & then taper to lower dose every 48 hours over the next 5-10 days
how do steroids work in stopping pruritus?
inhibit phospholipases of the cell membrane stopping the arachidonic acid cascade - stops inflammatory cytokines/signals/suppresses inflammatory response of the body
T/F: at least 1 elimination diet trail should be performed when a pruritic patient has signs that are non-seasonal
true
what are some clinical signs that may clue you in to a food allergy in a pruritic patient?
gi signs, pruritus, otitis, atopic dermatitis, & urticaria
T/F: in dogs with atopic dermatitis, 30% of them will also experience adverse food reactions/allergies
true
what is the difference between presenting signs of adverse food reactions in dogs & cats as far as lesion distribution & lesions go?
dogs - generalized pruritus, superficial pyoderma, otitis, hot spots, & atopic dermatitis
cats - cervicofacial pruritus, cutaneous reaction patterns
what are some common food offenders for cats & dogs with adverse food reactions/allergies?
dogs - beef, dairy, chicken, wheat, & lamb
cats - beef, fish, & chicken
how long should a diet trail last for a patient with adverse food reactions/allergies?
no more than 8 weeks
after a patient has completed a diet trial of 8 weeks, what do you do next?
challenge them with previous foods to determine if signs reoccur within 2 weeks
what are some examples of types of elimination diets/diet trials?
novel protein - venison, rabbit, kangaroo
hydrolyzed - chicken, soy, salmon
ultra-hydrolyzed - ultamino, EL
home prepared
T/F: a multi-modal approach or regimen of therapy will provide the best results given the complexity/pathophysiology of pruritus
true
why use essential fatty acids & ceramides when treating a pruritic patient?
omega 6 - improves epidermal barrier function & skin/coat luster
omega 3 - anti-inflammatory
ceramides - crucial in forming highly organized intercellular lipid lamellae in the stratum corneum, animals with atopic dermatitis has a deficiency of these which allows for allergen sensitization, infection, & dryness
how do antihistamines work?
block H1 receptors & some antimuscarinic receptors (anticholinergic) effects, so antipruritic & lil sedation
what animals have contraindications to antihistamines?
patients with a history of seizures, glaucoma, severe cardiac failure, urine retention, & ileus
how do TCAs work for pruritic patients?
block H1 receptors, block norepinephrine & serotonin presynaptic receptors in the brain & some antimuscarinic receptors (anticholinergic) effects
what are some side effects associated with TCAs?
tachycardia, arrhythmias, mydriasis, dry mouth, urine retention, constipation, & sedation
what animals have contraindications to TCAs?
similar to antihistamines - along with cardiac problems & concurrent use of MAO inhibitors, SSRIs, & other TCAs
when may TCAs be useful in pruritic cats?
in pruritic cats with self-induced alopecia when trying to figure out how much of the condition is related to a primary/secondary dermatological or behavioral disorder
what is canine atopic dermatitis?
genetically predisposed inflammatory & pruritic allergic skin disease with characteristic clinical features associated with IgE Ab most commonly directed against environmental allergens
how do calcineurin inhibitors, such as cyclosporine & tacrolimus, work for treating pruritus?
drug binds to t-lymphocyte cytoplasmic ligand & inhibits calcineurin (calcium-activated protein phosphatase) -> leads to dephosphorylation of cytoplasmic subunit of NFAT inhibited -> phosphorylated NFAT can’t translocate to the nucleus -> so the transcription of various cytokines is prohibited (IL-2, IL-4, TNF-alpha)
what side effects are associated with calcineurin inhibitors? any contraindications when using this drug?
inappetence, vomiting, diarrhea, increased hair shedding, hypertrichosis, gingival hyperplasia, papilloma-like skin lesions
don’t give to an animal with known neoplasia & no modified-live vaccines should be administered when a patient is on this drug
what contraindications do pruritic feline patients have in regards to cyclosporine?
don’t give to patients with FIV/FeLV, FIP, or known neoplasia
what precautions should be taken when prescribing cyclosporine to a cat?
needs to have a negative toxoplasma titer, look for any renal insufficiency, & diabetes mellitus - must avoid situations for toxoplasma exposure so no hunting/raw diets - need to keep cat inside)
what dosing is used for lokivetmab?
SQ injection every 4-8 weeks as needed at a minimum dose of 2mg/kg according to supplied dosing table
T/F: ASIT is a cure for atopic dermatitis
false
what drug is the mainstay therapy for treating demodicosis, scabies, & most ectoparasites?
isoxazolines - simparica, nexguard, bravecto, credelio
