Ectoparasites Flashcards
Fleas love
humidity
colorado have lower prevalence
What species is the common cat flea
Ctenocephalides felis
What is the primary lesion of an ectoparasite infestation
papule
Flea bite hypersensitivity is a reaction to
the flea allergen
burden does not equate with severity
What is the distribution of fleas
“Pants sign” -the caudodorsum of the animal
How can fleas present in cats
reaction pattern- eosinophilic granuloma/plaques, military dermatitis, indolent ulcers
How do you diagnose fleas
Combing
1) Flea dirt
2) actual observation of fleas variable- flea-nial?
they live off the host
What parasiticides are very toxic to cats *
Permethrins
What are different parasiticides
1) Permethrins- never for cats, only repellants
2) Neonicotinoids- bind to insect a-ch inhibition
Imidacloprid, dinotefuran, sinetoram/spinosad, nitenpyram
3) Phenylpyrazole
4) Avermectin- chloride channel agonists
5) Oxadiazine- blocks Na channels
6) Insect growth inhibitors (methoprene, lufenuron, pyriproxyfen)
How do you chose what type of parasiticide to give
-Effiacy
-Adverse Effects
-Ease of Use
-Cost
-Compliance
What is the mechanism of action of Isoxazolines (Bravecto, Nexgard, Simparica, Credelio)
potent inhibitor of y-aminobytyric acid (GABA)- gated chloride channels and L-glutamate gated chloride channels
What is the gold standard for flea treatments
Isoxazoline parasites (Bravecto, nexgard, simparica, credelio)
-kills 98%+ of fleas within 24 hours to halt the population
-adulticides preferred but IGRs can be supplementary
-1-2 months for resolution of flea allergic signs
How you you treat fleas
1) Isoxazoline parasites (Bravecto, nexgard, simparica, credelio)
-kills 98%+ of fleas within 24 hours to halt the population
-adulticides preferred but IGRs can be supplementary
-1-2 months for resolution of flea allergic signs
2) Use allergy meds
3) Topicals- pyrehtroid shampoos/sprays can help patient during eradication
sprays/vacuuming can help environment
foggers of limited use
What is the goal of tick control
Prevention of disease transmission - not eradication
no tick product kills ticks instantly (takes 48h for 90% kill)
disease transmission takes long time
What causes alpha-gal syndrome
A. americanum (lone star tick)
Isoxazolines kill fleas within _________ and have a _______ kill rate
kill ticks in about _____ and have a ______ kill rate
Fleas: kill within 24 hours and 98% rate
Ticks: kill within 48 hours and have 90% kill rate
What is the most pruritic dog disease
Sarcoptes scabei var. canis
Mange is a
mite infestation
What is the distribution of Sarcoptes scabei
Elbow
Distal limbs (carpi, tarsi)
Pinnae
they like the hairless/short hairs areas
this indication is very indicative of sarcoptes
rarely otitis occurs on pinnae
very pruritic
When Sarcoptes scabei is chronic you see
severe hypertrichosis and crusting of the distal pinnae
Why might sarcoptes scabei not cause pruritus in all animals in the house
one dog might not be hypersensitive to the bites
T/F: sarcpotes scabei is communicable between dogs and humans
True
How do you diagnose sarcoptes
*hard to find
1) Superficial skin scrapes (surface mites)
40% positive scrapes in confirmed cases
Pinnal-pedal reflex?
dont use ELISA
How do you treat Sarcoptes
On-label: Revolution (selamectin) month or Advantage multi (moxidectin) monthly
off-label: ivermectin, libemycin, doramectin, fipronil spray, amitraz, lime sulfur
Routine washing/vacuuming fine 2x weekly but mite is not long-lived in the environment
treat. patient symptomatically but often resistant to antipruritics
treat for 8 weeks- consider contagious for treatment duration
What species are resistant to sarcoptes
cats and horses
self-limiting in humans
T/F: Cheyletiellosis is zoonotic
True
Cheyletiellosis is the walking
dandruff
Is lice species specific
Yes
T/F: Cheyletiellosis is species specific
False- not necessarily
Cheyletiellosis is commonly transmitted in
high density and immunocompromised populations
Cheyletiellosis has what distribution
usually a dorsal distribution (scaly)
How do you diagnose Cheyletiellosis
Superficial scrapes
Flea combing
acetate tape preps
How do you treat Cheyletiella?
Same as Sarcoptes
-Ivermectin
-Salmectin
-Milbemyin
-Fipronil spray
-Lime sulfur (weekly)
-Treat for 8 weeks as a generic guidline
T/F: Demodex spp are contagious
False- they are not contagious but there are rare exceptions
Why is Demodex not a parasite
1) Disease of immunosuppression and overgrowth
youre suppose to have Demodex, just not a bunch of them
also they are species specific and not contagious
T/F: Demodex is a commensal organism
True- not a parasite, disease of immunosuppression and overgrowth
What are the two types of Demodecosis
1) Juvenile- immune system hasnt developed yet. lesions- alopecia, erthyema, papular dermatitis, folliculitis, collarettes
will resolve with immune maturity (localized) also generalized form
2) Adult-Onset: Immunocompromised (steroids, endocrine, neoplasia, apoquel, stress)- Generalized
What is the lifecycle of Demodex
1) Eggs (football-shaped, fusiform), hatch after 3-4 days
2) adult in a week (juvenilles 6 legs, adults 8)
3) Total lifecycle is 2-4 weeks
What is the classical presentation of Demodectic Mange
Diffuse alopecia, erythema, papules (and secondary crusts), comedones
demodex likes the face/eyes (more sebaceous glands)
What are the top 3 differentials for follicultis
1) Bacterial pyoderma
2) Dermatophytosis
3) Demodicosis
Adult onset Demodex
Always considered generalized
Always treat
Look for source of immunocompromise
What causes adult-onset Demodex
1) Immunomodulating drugs (Apoquel, steroids)
2) Endocrinopathies
3) Neoplasia
4) Stress
What species that if you see Demodex on them, it is very seriouds
Cat and Horses
What Demodex species is considered contagious
D. gatai - (surface mite) in the cats
not associated with immunosuppression
Cats have to be _____________ for Demodex cati
extremely immunocompromised
How do you diagnose Demodex
One mite with compatible clinical signs
-Deep skin scrapings (follicular*)
-Hair plucks (100 hairs)
-Exudate (purulent, cerumen)
-Acetate tape (more sensitive?)
-Gatoi: very difficult to find (fecals?)
dont diagnose by response to therapy
What is a less invasive way to find Demodex than a deep skin scrape
Trichogram- pluck 100 hairs (not as sensitive but easier and less invasive)
Acetate tape (more sensitive) with squeezing the skin, specifically the eggs and nymphs
Demodex can be via fecal flotation especially in
cats- groomers
How do you on-label treatment for Demodectic mange
On-label: Amitraz (Mitaban)
antagonistic effect on octopamine receptors of the nerve cells in the brain
topically every 2 weeks for 3-6 treatments
causes sedation (central alpha-adrenoreceptor agonist)
hair clipping
What is the on-label treatment for Demodex, although not often used
Amitraz (Mitaban)
antagonistic effect on octopamine receptors of the nerve cells in the brain
topically every 2 weeks for 3-6 treatments
causes sedation (central alpha-adrenoreceptor agonist)
hair clipping
What is the mechanism of action of macrocyclic lactones (ivermectin, selamectin, moxidectin, doramectin, milbemycin)
stimulation of glutamate and GABA-gated chloride channels
macrocyclic lactones (ivermectin, selamectin, moxidectin, doramectin, milbemycin) should not be used in what dogs
those with the MDRI (ABCB1) mutation
might be able to tolerate 3x daily dosing
How has demodectic mange historically been treated
macrocyclic lactones (ivermectin, selamectin, moxidectin, doramectin, milbemycin)
stimulate glutamate and GABA-gated chloride channels
typically daily therapy
Cats- lime sulfur dips weekly
What is the MDR-1 (ABCB1) gene mutation
a gene mutation that results in incomplete p-glycoprotein synthesis; important component of blood barrier- drug efflux pump (prevents ivermectin from accumulating in the brain)
Homozygous- toxicity
common in Australian Shepherds, border collies, german shephard
How is demodectic mange treated today
Isoxazolines!
can also combine with a macrocyclic lactone
What is a common ectoparasite in large animals
Chorioptes - like long hairs
tx: ivermectin, topical fipronil and lime sulfur weekly
isoxazoline?
what is the ear mite
Otodectes cynotis
How do you treat otodectes cynotis
three doses required? ISmparica
resolived in 14 days with Bravecto (cat topical)
All others two monthly doses recommended
Pediculosis is infestation of
Lice
What are the chewing lice
Dogs: Trichodectes canis
Cats: Felicola subrostrata
What species is the dog sucking louse
Linognathus setosus
Unlike fleas, lice live
on the host
T/F: lice are species specific
True
How do you treat pediculosis in horses
use topicals (pyrethroids lime sulfur, fipronil)
Isoxazoline products have been associated with
Neurologic adverse reactions
- muscle tremors
-ataxia
-seizures
but very rare and self-limiting (only a few days)
what should you do for culicoides hypersensitivity in horses
Must reduce exposure to butes of biting midges
stable at night
fans
blankets/coverings
pyrethrins/pyrethroids
sometimes steroids, antihistamines (insect-bite hypersensitivity/allergy)
