Scabies Flashcards
Describe canine scabies
- parasitic, contagious dz
- caused by Sarcoptes scabiei var. canis
- one species and numerous varieties adapted to different hosts
-
mite is not host specific
- zoonotic dz
-
mite is not host specific
Describe Sarcoptes
- male mite lives on skin surface
- fertilized females burrow into the str. corneum
- 4 stages:
- eggs
- larvae (6 legs)
- nymphs (6 legs)
- adult (8 legs)
- life cycle: 3 wks
How is Sarcoptes transmitted?
- by direct contact
- does not survive in the environment very long (up to 48h)
Describe the clinical presentation of sarcoptic infestation in humans
- zoonotic dz
- reactions in humans occur within 24h
- pruritic papules
- var. canis usually does not reproduce on human skin
- lesions resolve within 12-14d, if no further contact with affected dogs
What is the pathogenesis of a sarcoptes infestation?
- incubation period unknown
- typically 21-30d (1-60d)
- rapidity and severity of lesions and pruritus depend on:
- previous exposure
- # of mites
- hypersensitivity
- mechanic irritation
- pruritogenic substances from saliva and feces
What are the clinical features of canine scabies?
- intense pruritus!
- predilection for areas w/ low hair density
- ventral abdomen
- pinnae (esp. margins)
- hocks
- elbows
- primary lesion: papule
- excoriations, crusts, alopecia
- secondary infections
Describe the clinical features of chronic canine scabies
- hyperpigmentation
- lymphadenopathy
- weight loss
- hyperglobulinemia
Describe “Norwegian scabies”
- rare form
- thick crusts
- numerous mites
-
little pruritus
- immunosuppressed animals
- animals receiving glucocorticoids
- puppies
Describe “scabies incognito”
- well groomed animals
- intense pruritus
- no lesions
How do you diagnose Scabies?
- Clinical dx:
- intense pruritus
- papular eruption
- typical distribution of the lesions
- Superficial skin scrapings (KOH to facilitate digestion):
- positive <50% of the time
- Best areas to scrape
- margins of pinnae
- elbows
- hocks
- response to tx
- if you suspect it, treat it
What is the therapy for scabies?
- Topical
- lime sulfur dips (Lym Dip)
- Selamectin (Revolution)
- Fripronil (Frontline)
- Bravecto
- Moxidectin (Advantage Multi)
- Oral
- Ivermectin
- Milbemycin
- Bravecto, Nexgard, Simparica
What are some general considerations you should have when treating scabies?
- treat all animals in contact
- length of treatment
- treat secondary infections
- pruritus may persist for a short period of time after treatment
- resistance may develop w/ any product
- clean environment
Describe LymDip
- faster relief
- strong antipruritic
- 4-6 oz/gallon of water
- use 1x/5 days for 7-8 times
- yellow staining
- sulfur smell
- drying
Describe Phosmet (Paramite)
- Freq resistance
- not recommended any longer
Describe Fipronil
- reported to kill Sarcoptes
- not frequently used as treatment
- larger doses than normal are required
- freq tx
Describe Selamectin (Revolution) treatment
- Label
- suggested regimen: 1 dose/2 wks for 3 times
Describe Ivermectin treatment
- 250-300 mcg/kg 1x/2 wks for 3 times
- check HW status
- do not use in Collies, Shelties, Corgies, English Sheepdogs
Describe Bravecto, Nexgard, Simparica, and Advantage Multi treatments
- all effective treatments at labeled dose and frequency
- Simparica was shown to be statistically non inferior to Advantage Multi
Describe Notoedric mange (feline scabies)
- rare, zoonotic dz
- resembles Sarcoptes
- life cycle: 21d
What are the clinical signs of feline scabies?
- extreme pruritus
- erythema, crusting, papules
- distribution:
- head and neck
- generalized
How do you diagnose feline scabies?
- clinical signs
- superficial skin scrapings
- freq positive for mites
- response to tx
How do you treat feline scabies?
- LymDip
- Revolution
- Ivermectin
- Bravecto (topical for cats)
- All in contact animals need to be treated
- Tx should be extended beyond the duration of a life cycle
Describe Cheyletiella (“walking dandruff”)
- obligate parasite
- large parasite with hook-like mouthparts
- spends all its cycle on the host
- can live off the host for up to 10d
- Three species:
- C. yasguri (dogs)
- C. parasitovorax (rabbits)
- C. blakei (cats)
How does Cheyletiella exert its effects?
- digesting enzymes are excreted by the mite
- mites eat the dissolved skin
- skin irritation and subsequent scratching
- hair loss, scabs and wounds
Describe the transient zoonosis caused by Cheyletiella
- papular eruption and pruritus
- unable to reproduce on human skin
- self-limiting once source of infestation has been removed
Describe the life cycle of Cheyletiella
- complete in 3 weeks
- eggs
- larvae (6 legs)
- nymphs (8 legs)
- adults (8 legs)
What are the clinical signs of a Cheyletiella infestation in dogs?
- usually puppies
- scaling and pruritus
- dorsal distribution
What are the clinical signs of a Cheyletiella infestation in cats?
- miliary dermatitis
- mild/moderate pruritus
- asymptomatic carriers
What are the clinical signs of a Cheyletiella infestation in rabbits?
- scaling
- scapular area often affected
- no primary lesions
How do you diagnose Cheyletiella infestation?
- demonstration of eggs or mites
- combing technique
- superficial skin scrapings
- cellophane tape impressions
How do you treat Cheyletiella infestations?
- easily killed by most insecticides
- pyrethrin
- lime sulfur dips
- ivermectin
- fipronil
- selamectin
- environment should be cleaned
- do not use Fipronil in rabbits!
What are the organisms involved in pediculosis?
- two species affecting dogs
- biting lice
- Trichodectes canis
- sucking lice
- Linognatus setosus
- biting lice
Describe pediculosis
-
host specific
- not a zoonosis!
- spends all life cycle on host
- life cycle: 3 wks
- limited survival in the environment
- spreads by direct contact
What are the clinical signs of pediculosis?
- esp. in winter months
- variable C/S:
- asymptomatic - intense pruritus
- few direct lesions
- secondary excoriations
- seborrhea
- anemia
- matted coat with nits (eggs)
How do you diagnose pediculosis?
- physical ID of lice and eggs
- brush or acetate tape impression method used to immobilize lice
- magnifying lens facilitate detection
How do you treat pediculosis?
- clip coat in long-haired animals
- treat to cover the life cycle
- easily killed
- pyrethrin
- fipronil
- lime sulfur dips
