Dermatology - Flea Allergy, Scabies, Malassezia

sihirlifil's version from 2017-10-04 21:41

Flea Allergy

Question Answer
Definition of flea allergyType I or Type IV hypersensitivity
Flea allergy: age onsetAround 1 year (some older)
Flea allergy: Seasonal?Can be! Fleas need humidity, can be killed off in winter (heaters high, dry out)
Flea allergy: distribution pattern in dog? Cat?Dog: Back half of body
Cat: Back half and/or head and neck (posterior 1/3) (ddx atopy, food allergy)
Flea allergy: concurrent?80% fo atopic dogs also have flea allergy!
“Classic mohawk” =Flea allergy
Flea allergy: CS in dogs? Cats?Dogs: erythema, INTENSE PRURITIS!, hyperpigmentation, alopecia (mohawk pattern) (most are secondary lesions… can have papule where flea bit)
Cats: Miliary/crusted papules
If you suspect your feline patient has flea allergies, what test should you keep in mind?Fecal float! Can ingest while grooming
Flea allergy in cats: same CS as what? (ddx)Atopy, food allergy
Look at flea/food exposure, hx
T/F Dogs constantly exposed to fleas are more likely to develop allergiesF
Intermittent exposure favors allergic state
Flea allergy DdxAtopy
Food allergy
Bacterial pyoderma
Flea allergy: diagnosis?Hx & CS
Flea antigen can be injected intraderm, but gives false negatives if Type IV HS (delayed type)
What’s so important about the flea life cycle?Need to understand the role of the environment, where fleas like to live e.g. need shade, protection… (also, adults are only 5% of total population! Eggs = 50%, larvae = 35%, pupae = 10% so consider how to tx environment too)
Flea allergy: do we want eradication or control?Eradication
Consider recommending a professional exterminator when…Have pets with flea allergy
Where is it best to break flea life cycle?Reproduction (Critical point)
Flea allergy: treatment options for dog?Treat pyoderma
Oral pred higher dose to start (but not injectable- easier to control doses, can repeat, can’t take back if SEffx)
(Cytopoint only for atopy, but can try?)
Flea allergy: treatment options for cat?Methylprednisolone (better than Pred, more potent) (4mg MPred = 5mg Pred)
Depo Medrol (injectable)- good for cats that are hard to pill
Antibiotics for 2ry pyoderma
Major factors for product selection (3)Spectrum (add tick if also problem)
Efficacy (need to get population to 0, stop the biting b/c saliva = allergen)
Minor factors for product selection (5)Ease of application (topical vs. chewable)
Owner compliance (need to teach how to apply correctly)
Age restrictions
Hair coat density

Flea Products

Question Answer
Pyrethrins: good for fleas?NO! Only drug fleas have developed resistance to, and pass gene along
Pyrethrins: Benefits?Quick kill (prolongs Na conductance)
Repellant (don’t get chance to bite)
Pyrethrins: Downsides?Short lasting
Pyrethrins: treatment?Spray towel and wrap puppy/kitten
Permethrins: mechanism?Same as pyrethrins, just synthetic (prolong Na channel conductance) but slower kill
Permethrins: good for fleas? (…who?)Not the best
Human use: #1 for tick avoidance! Drench clothing, let dry, remains for 5 washes
Permethrins: special thing?UV stable
T/F Permethrins are toxic to catsTRUE! Reversal = IV lipid (block/slow the receptors)
Organophosphates: what kind of drug?Cholinesterase inhibitor
Organophosphates: Toxic in?Cats (of course)
How to reverse organophosphate toxicity in cats:2-PAM or atropine (NAVLE)
Organophosphates: formulationsChlorpyrifos
Fipronil: aka?Frontline
Fipronil: MOA?Inhibits GABA-mediated Cl- flux & blocks glutamate-gated Cl- channels
Fipronil: good for fleas?Losing efficacy over time for fleas, so not recc as sole product
Works on ticks
Imidacloprid: aka?Advantage
Imidacloprid: MOA?Stops post-syn binding of ACh
Imidacloprid: good for fleas?WORKS FOR FLEAS ONLY! If you want flea & tick use something else, good in combo products (K9-Advantix II, Advantage Multi, Seresto)
Imidacloprid+Permethrin: aka?(+Pyriproxyfen) K9-Advantix II
Imidacloprid+Permethrin: how do you use for flea-allergic dog?Collar + something else
Imidacloprid+Permethrin: danger?Seresto collar = major reason for toxicity in cats! (Inadvertent application)
Imidacloprid+Moxidectin: aka?Advantage Multi
Imidacloprid+Moxidectin: good for fleas? Anything else?Yes, not so much for ticks
Scabies & ear mites off-label
Imidacloprid+Moxidectin: age restriction for dog? Cat?Dog: 7 weeks
Cat: 9 weeks
Selamectin: aka?Revolution
Selamectin: good for fleas? (spp diff)DOG: Slow kill :( so clinically not good, but great for Scabies
CAT: yes! also heartworm (great for indoor cat)
Dinotefuran: aka?Vectra
Dinotefuran: what drugs? What do they do?Permethrin
Pyriproxyfen: environmental control! Insect growth regulator stops eggs from hatching to larvae & larvae from maturing
Dinotefuran: age restriction?Dogs >7 weeks AND >2.5#
Dinotefuran: caution?Not good if also have cats: can make a big wet spot after application
Imidocarb +/- Permethrin: aka?Activyl Tick Plus
Imidocarb +/- Permethrin: which drug is good for what?Imidocarb for ONLY FLEAS!
Permethrin gets ticks
Imidocarb +/- Permethrin: how does it work?Bioactivated by enzymes in the flea gut. So flea must eat it to be effective, ingest by grooming themselves (ew), no efficacy against mammals
Imidocarb +/- Permethrin: Good qualities?Rapid absorption, low volume, controlled distribution
Imidocarb +/- Permethrin: age restriction?>8 weeks
Nitenpyram: aka?Capstar! (we give sx doggies in JSAL)
Nitenpyram: good for fleas? And?YES causes adults to die within minutes, but only lasts 24 hours
ALSO MAGGOTS! just climb out, drop off and die
Nitenpyram: special admin?Can apply per rectum during surgery
Nitenpyram: age restrictions?>4 weeks and >2#
Spinosad: aka?Comfortis
Spinosad: admin?Oral montly
Spinosad: age restriction?Dogs & cats >14 weeks
Accidental deaths from tx demodex w/ ivermectin concurrently
Spinosad: good for fleas?FLEA ONLY but efficacy drops, bad for allergy patients because fleas feed before dying
Spinosad+Milbemycin: aka?TriFexis
Spinosad+Milbemycin: good for fleas?ADULT fleas, also heartworm, hooks, rounds, whips
Spinosad+Milbemycin: age restriction? (other?)DOGS ONLY
>8 weeks & >5#
Afoxolaner: aka?NexGard
Afoxolaner: good for fleas?Flea & tick
Off-label for demodex
Afoxolaner: admin?Chewable monthly (beef flavor- not good for food trials?)
Afoxolaner: age restriction? (other?)DOGS ONLY
>8 weeks and >4#
Afoxolaner: SEffx?Vomiting
Pemphigus foliaceous can develop following second admin
Fluralaner: aka?Bravecto
Fluralaner: good for fleas?4 species of flea & tick
Off-label for generalized demodex (re-scrape once a month)
Fluralaner: age restriction? (other?)DOGS ONLY
>6 months & >4.4#
Fluralaner: duration of activity?12 weeks, but 8 weeks for Lone Star tick
Fluralaner: admin?Labeled for 3m therapy, chewable hydrolyzed pork (food trial!)
Re-dose if vomit w/in 3 hours
Fluralaner: special condition it CAN be used?Only product labeled for breeding, lactating or pregnant dogs
Sarolaner: aka?Simparica
Sarolaner: good for fleas?Fleas & ticks
Not good for juvenile demodex (unlike fluralaner)
Sarolaner: age restriction? (other?)DOGS ONLY
>6 months & >2.8#
Sarolaner: duration of activity?30 days
Sarolaner: why do we care about a certain ingredient?Liver flavor = NOT GOOD FOR FOOD TRIAL
Insect growth regulators do what?Mimic juvenile hormone
Lufenuron: MOA?Chitin synthesis inhibitor (IGR)
Lufenuron: can you use by itself?No. Fleas lay eggs that don’t hatch (stops reproduction), great for environmental control, but doesn’t kill adults
(Worthless flea products)Tea tree oil, D-limonene (toxic to dogs & cats), Pennyroyal oil (hepatotoxic in dogs), Brewer’s yeast (feeds the fleas), Garlic, Ivermectin, ultrasound collars


Question Answer
Species of sarcoptesS. scabiei (var canis, suis…) Reportable in cattle, horses
Notoedres cati
Special thing about life cycle?Entirely on host for about 21 days
Adults feed & breed in superficial stratum corneum (burrowing = CS persist), larvae migrate to surface to mature
Etiology of scabiesType 4 hypersensitivity
Response to steroids?DOESN’T RESPOND! Type IV HS
Clinical signs of scabies?Mild pruritic, becomes intense within 21-30 days (variable pruritic in multi-dog households)
Erythema, papules
Head shaking, scratching can lead to aural hematoma
Distribution of scabies lesionsEar margin
Ventrum incl. sternum
Diagnosis of scabiesSuperficial skin scrape (e.g. margins of ear pinna), but only need a few mites for CS! (<5!) so if you cant find the organism and CS match, treat
Treatment optionsSelamectin 100% effective!
Lime sulfur great for long term, antipruritic
Something to note about starting the treatment?Itching will get worse for a few days as mites burrow. May need steroids/Apoquel to reduce the itch first
Itching may persist for weeks following tx
Using ivermectin off-label: Breeds to avoid??Collie/Sheltie
Border Collie
Australian Shepherd
Side effects of ivermectinSalivation, mydriasis
CONTRAINDICATION OF IVERMECTINSPINOSAD (need high dose of ivermectin for scabies!)
How to treat ivermectin toxicity:IV lipids
T/F Many N. cati mites are needed for CS, as apposed to sarcoptesTrue, need huge numbers
CS of Notoedres catiPruritis
Tx of Notoedres cati(same as sarcoptes)

Malassezia Dermatitis

Question Answer
Which age is most susceptible?Any!
CS?Moderate to severe pruritis, commonly present with odor
Where does Malassezia come from? what environment does it like?Opportunist! All dogs have it on skin
Thrives in greasy haired skin, after traumatized (lichenified, hyperpigmented(?))
Diagnosis?Cytology (scotch tape prep direct impression smear)
If treatment failure, do what?Cytology, could be other contributing factors
Treatment optionsKetoconazole
Treatment of choice in dogsKetoconazole (SEffx vomiting)
What makes ketoconazole so good at treating?Concentrates in sebum (good delivery)
Anti-inflammatory, reduces pruritis quickly
Preferred treatment for catsFluconazole (gets into mucosal surfaces)
And Ketoconazole kills cats... so don't use it
How’s Terbinafine?Not good, don’t use
LSD effective to treat?Pruritis. Very effective
Topical drugs for Malassezia?LSD
Climbazole (good in shampoo)

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