Scabies

Question 1

Describe canine scabies

Answer 1

• 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

Question 2

Describe Sarcoptes

Answer 2

• 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

Question 3

How is Sarcoptes transmitted?

Answer 3

• by direct contact
• does not survive in the environment very long (up to 48h)

Question 4

Describe the clinical presentation of sarcoptic infestation in humans

Answer 4

• 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

Question 5

What is the pathogenesis of a sarcoptes infestation?

Answer 5

• 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

Question 6

What are the clinical features of canine scabies?

Answer 6

• intense pruritus!
• predilection for areas w/ low hair density
  
  • ventral abdomen
  • pinnae (esp. margins)
  • hocks
  • elbows
• primary lesion: papule
• excoriations, crusts, alopecia
• secondary infections

Question 7

Describe the clinical features of chronic canine scabies

Answer 7

• hyperpigmentation
• lymphadenopathy
• weight loss
• hyperglobulinemia

Question 8

Describe “Norwegian scabies”

Answer 8

• rare form
• thick crusts
• numerous mites
• little pruritus
  
  • ​immunosuppressed animals
  • animals receiving glucocorticoids
  • puppies

Question 9

Describe “scabies incognito”

Answer 9

• well groomed animals
• intense pruritus
• no lesions

Question 10

How do you diagnose Scabies?

Answer 10

• 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

Question 11

What is the therapy for scabies?

Answer 11

• Topical
  
  • lime sulfur dips (Lym Dip)
  • Selamectin (Revolution)
  • Fripronil (Frontline)
  • Bravecto
  • Moxidectin (Advantage Multi)
• Oral
  
  • Ivermectin
  • Milbemycin
  • Bravecto, Nexgard, Simparica

Question 12

What are some general considerations you should have when treating scabies?

Answer 12

• 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

Question 13

Describe LymDip

Answer 13

• faster relief
• strong antipruritic
• 4-6 oz/gallon of water
• use 1x/5 days for 7-8 times
• yellow staining
• sulfur smell
• drying

Question 14

Describe Phosmet (Paramite)

Answer 14

• Freq resistance
• not recommended any longer

Question 15

Describe Fipronil

Answer 15

• reported to kill Sarcoptes
• not frequently used as treatment
  
  • larger doses than normal are required
  • freq tx

Question 16

Describe Selamectin (Revolution) treatment

Answer 16

• Label
• suggested regimen: 1 dose/2 wks for 3 times

Question 17

Describe Ivermectin treatment

Answer 17

• 250-300 mcg/kg 1x/2 wks for 3 times
• check HW status
• do not use in Collies, Shelties, Corgies, English Sheepdogs

Question 18

Describe Bravecto, Nexgard, Simparica, and Advantage Multi treatments

Answer 18

• all effective treatments at labeled dose and frequency
• Simparica was shown to be statistically non inferior to Advantage Multi

Question 19

Describe Notoedric mange (feline scabies)

Answer 19

• rare, zoonotic dz
• resembles Sarcoptes
• life cycle: 21d

Question 20

What are the clinical signs of feline scabies?

Answer 20

• extreme pruritus
• erythema, crusting, papules
• distribution:
  
  • head and neck
  • generalized

Question 21

How do you diagnose feline scabies?

Answer 21

• clinical signs
• superficial skin scrapings
  
  • freq positive for mites
• response to tx

Question 22

How do you treat feline scabies?

Answer 22

• 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

Question 23

Describe Cheyletiella (“walking dandruff”)

Answer 23

• 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)

Question 24

How does Cheyletiella exert its effects?

Answer 24

• digesting enzymes are excreted by the mite
  
  • mites eat the dissolved skin
• skin irritation and subsequent scratching
  
  • hair loss, scabs and wounds

Question 25

Describe the transient zoonosis caused by Cheyletiella

Answer 25

• papular eruption and pruritus
• unable to reproduce on human skin
• self-limiting once source of infestation has been removed

Question 26

Describe the life cycle of Cheyletiella

Answer 26

• complete in 3 weeks
  
  • eggs
  • larvae (6 legs)
  • nymphs (8 legs)
  • adults (8 legs)

Question 27

What are the clinical signs of a Cheyletiella infestation in dogs?

Answer 27

• usually puppies
• scaling and pruritus
• dorsal distribution

Question 28

What are the clinical signs of a Cheyletiella infestation in cats?

Answer 28

• miliary dermatitis
• mild/moderate pruritus
• asymptomatic carriers

Question 29

What are the clinical signs of a Cheyletiella infestation in rabbits?

Answer 29

• scaling
• scapular area often affected
• no primary lesions

Question 30

How do you diagnose Cheyletiella infestation?

Answer 30

• demonstration of eggs or mites
  
  • combing technique
  • superficial skin scrapings
  • cellophane tape impressions

Question 31

How do you treat Cheyletiella infestations?

Answer 31

• easily killed by most insecticides
  
  • pyrethrin
  • lime sulfur dips
  • ivermectin
  • fipronil
  • selamectin
• environment should be cleaned
• do not use Fipronil in rabbits!

Question 32

What are the organisms involved in pediculosis?

Answer 32

• two species affecting dogs
  
  • biting lice
    
    • Trichodectes canis
  • sucking lice
    
    • Linognatus setosus

Question 33

Describe pediculosis

Answer 33

• host specific
  
  • ​not a zoonosis!
• spends all life cycle on host
• life cycle: 3 wks
• limited survival in the environment
• spreads by direct contact

Question 34

What are the clinical signs of pediculosis?

Answer 34

• esp. in winter months
• variable C/S:
  
  • asymptomatic - intense pruritus
• few direct lesions
• secondary excoriations
• seborrhea
• anemia
• matted coat with nits (eggs)

Question 35

How do you diagnose pediculosis?

Answer 35

• physical ID of lice and eggs
• brush or acetate tape impression method used to immobilize lice
  
  • magnifying lens facilitate detection

Question 36

How do you treat pediculosis?

Answer 36

• clip coat in long-haired animals
• treat to cover the life cycle
• easily killed
  
  • pyrethrin
  • fipronil
  • lime sulfur dips