Scabies & Demodex Flashcards
What is scabies caused by?
Sarcoptes scabei var. canis
Is the scabies mite host specific?
No; zoonotic disease
How long is the scabies mite life cycle?
3 weeks
How is scabies transmitted?
Direct contact
What is the pathogenesis of pruritis with scabies?
Hypersensitivity
Mechanic irritation
Pruritogenic substances from saliva and feces
What are the classic sites of infection for scabies?
Ventral abdomen
Pinnae
Hocks
Elbows
What is the primary lesion for scabies? Secondary lesions?
Primary - papule
Secondary - crusts, alopecia, excoriations, secondary infections
What are some clinical signs of chronic scabies?
Hyperpigmentation
Lymphadenopathy
Weight loss
Hyperglobulinemia
What is norwegian scabies?
Rare form that causes thick crusts
Numerous mites
Little pruritus
Seen in immunosuppressed animals
What is scabies icognito?
Well groomed animals
Intense pruritus
No lesions
How do you diagnose scabies?
Skin scrape (pinnae, elbows, hocks)
What is the treatment for scabies?
Topical:
Lime sulfur dips
Selamectin
Fipronil
Systemic:
Ivermectin
Milbemycin
What is feline scabies?
Notoedric mange, caused by Notoedres mite
Causes extreme pruritus on head and neck
What is cheyletiella?
“Walking dandruff”
Produce digesting enzymes and eat dissolved skin of host
Causes irritation, hairloss, scabs
3 types for dogs, rabbits, cats
Is cheyetiella zoonotic?
Yes, can cause papular eruption and pruritus
Cannot reproduce on human skin
Self-limiting
How long is the lifecycle of cheyetiella?
3 weeks
How do you treat cheyetiella?
It’s easily killed by most insecticides
Environment should be cleaned
Don’t use fiipronil on rabbits
What is pediculosis?
Lice, two types:
Biting (trichodectes canis)
Sucking (linognatus setosus)
Is pediculosis zoonotic?
no, host-specific
How is pediculosis diagnosed?
Physical identification of lice and eggs
How is pediculosis treated?
Clip coat in long-haired animals
Treat to cover lifecycle
Pyrethrin, fipronil, lime sulfur
How long is the lifecycle of the demodex mite?
25-30 days
How is demodex transmitted?
Mites transmitted to pups from bitch in the first 1-3 days of life
Present in low numbers in healthy post-natal dogs
Disease is caused by abnormal proliferation
What is the pathogenesis of demodecosis?
Deficient cell-mediated immune response
Genetics (autosomal recessive)
Immunosuppression
Bacterial folliculitis
Is demodex contagious or zoonotic?
No
What are the clinical signs of demodex?
Papules/pustules, erythema Alopecia Scaling, crusting Comedones Patchy alopecia Hyperpigmentation
What are the three techniques to diagnose demodex?
Deep skin scrape
Hair plucks
Biopsy
What are the different types of demodex?
Juvenile onset
Adult onset
Localized
Generalized
For breeding animals, why would you want to wait and see if localized demodex will eventually become generalized?
To know/discuss prognosis
To make recommendations about neutering
What percent of localized demodicosis will resolve on its own? What percent will generalize?
90% will clear
10% will generalize
How do you treat juvenile demodicosis?
Benign neglect
Antibiotics
Benzoyl peroxide shampoo (2-3%.. less than human dose!)
Deworming, good diet, etc.
Why would you not treat demodicosis with miticides?
To know if it will become generalized
Prevent unnecessary medical treatment
How should you monitor localized demodicosis?
Deep skin scrapes in 5 spots
If mite count decreases and lesion is resolving. Recheck q4weeks until resolves
If mite count increases, and other sites are positive, may be progressing to generalized
What is it called if demodicosis involves two or more feet?
Pododemodicosis
What should be considered for adult demodicosis?
If there is any underlying immunosuppression…
steroid misuse, endocrine disease, metabolic disease, neoplasia
What percent of juvenile generalized demodicosis will self-clear?
50% self clear
50% require treatment
How do you treat generalized demodicosis?
Miticide (Amitraz, milbemycin, ivermectin, moxidectin, bravecto)
Antibiotics
Benzoyl peroxide
When should you not use amitraz to treat demodicosis?
Patients that are: toy breeds, sick, old, have extensive ulcerations
Owners that have: asthma diabetes taking MOA (Parkinson’s)
What is the only FDA approved treatment for demodicosis?
Amitraz
Why should you not give ivermectin to collies, shelties, australian shepherds, etc?
MDR1 gene deletion causes
Defect in proton pump (P-glycoprotein)
Drug crosses into brain but not pumped out efficiently
How long should you treat demodicosis with ivermectin?
Until 3 negative skin scrapes at 4 week intervals
5 sites each time, always include muzzle and feet
What percent of generalized demodex is juvenile?
97%
What breeds are hard to cure of demodex?
OESD
Afghan Hound
Shih Tzu
Lhasa Apso
What species of mites cause feline demodicosis?
D. Cati
D. Gatoi
What is the difference between D. Cati and D. Gatoi?
D. Cati - follicular mite, due to immunosuppression, variably pruritic, need deep scrape
D. Gatoi- stratum corneum mite, contagious, very pruritic, superficial skin scrape, common in Texas
How do you treat feline demodicosis?
D. Cati- ivermectin
D. Gatoi- ivermectin, lime dip
How can you tell the difference between D. Cati and D. Gatoi under the microscope?
D. Cati is long and narrow
D. Gatoi is short and wide
