Unit 2 - Mites Flashcards
What are two orders of mites and ticks?
Acariformes (mites), Parasitiformes (mites, ticks)
How are mites and ticks different?
size, time/location on host, some life cycle stages, some aspects of morphology
List the mange mite groups:
- Sarcoptes
- Notoedres
- Chorioptes
- Psoroptes
- Demodex
List the ear mite groups:
- Otodectes
- Psoroptes cuniculi
What is the general pathogenesis of acariasis?
- most affect the skin
- related to where mites are going to be
General life cycle of parasitic mites:
- life cycle occurs on host
- mostly in epidermis
- over 2-3 weeks
Sarcoptes scabei: host-specific variants vs. species?
host-specific
S. scabiei hosts:
wide range of hosts, except CATS (rare)
S. scabiei life cycle:
- on host
- in epidermis (just below the stratum corneum)
- over 2-3 weeks
What are the clinical signs of sarcoptic mange?
- papules, erythema, pruritis –> hyperkaratosis, alopecia
- self-trauma, secondary infections, crusting
Severed scabies:
“crusted scabies”
Scabies common name in dogs:
itch mite
Scabies common name in cattle:
barn itch
Scabies common name in sheep/goats:
head scab
Scabies common name in horses:
no name
Scabies common name in pigs:
no name, but common!
Initial lesion seen with itch mite in dogs:
lateral elbows, lateral hocks, edge of pinna
Initial lesion seen with barn itch in cattle:
abdomen, neck, medial hind legs
Initial lesion seen with head scab in sheep/goats:
face, ears, ventrum
Initial lesion seen with scabies in horses:
neck, shoulders, face
Initial lesion seen with scabies in pigs:
ears, back
Diagnosis methods for Sarcoptes scabiei:
- skin scraping (negatives not conclusive)
2. response to treatment
What’s important to remember about treating scabies?
treat all contact animals of same species
Scabies zoonotic potential?
non-human variants
Notoedres cati host:
wild or domestic felids
How long is the life cycle of Notoedres cati?
~3 weeks
Pathogenesis of N. cati:
thick, scaly skin, pruritis –> self trauma, systemic signs
Very similar to sarcoptic mange in dogs, though mainly affects head & neck:
N. cati
Does N. cati have zoonotic potential?
yes
Diagnosis and tx for Notoedres cati:
same as S. scabei; tx w/ ivermectin, also lime sulfur dips
Hosts for Psoroptes cuniculi:
rabbits, goats, horses
Psoroptes spp. in large animals is:
reportable!
Psoroptes life cycle:
- non-burrowing on skin (do not bury deep)
- ~2-3 weeks
Common name of Psoroptes in cattle:
cattle scab
initial lesions associated with cattle scab:
back, tail, head, shoulders
Common name of Psoroptes in sheep/goats:
scab
Initial lesions associated with Psoroptes in sheep/goats:
neck, back
Common name of Psoroptes in horses:
not common
Initial lesion associated with Psoroptes in horses:
base of mane
Foot and tail mange of large animals; not reportable in any host:
Chorioptes spp.
Chorioptes spp. host:
cattle, horses
Chorioptes spp. life cycle:
- ~3 weeks
- non-burrowing
Clinical signs/Pathogenesis for Chorioptes spp.:
mild to none
Common names for cattle Chorioptes:
- Foot & Tail mange
- tail scab
Initial lesions of cattle Chorioptes:
base of tail, udder, hind feet
Common names for Sheep/Goat Chorioptes:
foot & tail mange
What are the initial lesions for sheep/goat Chorioptes:
interdigital, base of tail, scrotum
Common names for horse Chorioptes:
foot mange, itchy leg
Initial lesions of horse Chorioptes:
foot, base of tail
Otodectes cynotis:
ear mites
Otodectes cynotis hosts:
dogs, cats, ferrets…
How long is the life cycle of O. cynotis:
about 3 weeks
Clinical Signs/Pathogenesis of Otodectes cynotis:
- inflammation and trauma of feeding mites
- self trauma
- canals become excessively moist (cerumen - purulent black exudate)
- inflammation –> pruritis –> self-trauma
How do you diagnose Otodectes cynotis?
ear swabs
O. cynotis treatment:
- avermectins preferred (topical or systemic)
- repeated (2 treatments, two weeks apart) may be necessary
- treat all animals in household!!
Normal fauna of host skin:
Demodex
Demodex hosts:
species-specific
Demodex species for humans:
D. brevis, D. folliculorum
Demodex life cycle:
- completed in hair follicles or sebaceous glands
- no mites in environment
- ~ 20-35 days
- all stages by direct transmission contact
2 forms of demodicosis:
- squamous
2. papulonodular
Clin path of squamous demodicosis:
dry, scaly, dermatitis, alopecia
Squamous demodicosis can be:
localized or generalized
Which type of demodectic mange has no age predilection?
generalized
Which type of demodectic mange affects dogs <1 yr old?
localized
Which type of demodectic mange is a little hereditary?
localized
Which type of demodectic mange is small, well-defined, and patchy?
localized
Which type of demodectic mange has large, coalescing lesions that leads to pruritis and secondary infection?
generalized
Which form of demodectic mange is best left alone?
localized
Which type of demodectic mange has a poor prognosis if left untreated?
generalized
How do you treat generalized demodectic mange?
- high dose, long term daily avermectin
- spay intact females
- manage underlying cause
Feline demodectic mange affects:
any age/breed but is uncommon and may go unrecognized
Large animal demodicosis is common in cattle that are:
pregnant/lactating
Initial lesions associated with large animal demidocosis in cattle:
nodular-neck, shoulders
Is large animal demodicosis common in sheep?
rare
Is large animal demodicosis common in horses?
rare
Is large animal demodicosis common in pigs?
rare
Large animal demodicosis is common in goats that are:
young/pregnant
Initial lesions associated with large animal demidocosis in sheep:
diffuse; scaly - neck, flank, shoulders
Initial lesion associated with large animal demidocosis in goats:
nodular - face, neck, axilla, udder
Initial lesion associated with large animal demidocosis in horses:
diffuse; scaly
Initial lesion associated with large animal demodicosis in pigs:
nodular - snout
Cheyletiella hosts:
dogs, cats
Cheyletiella life cycle:
- ~35 days
- non-burrowing
Cheyletiella clinical signs/pathogenesis:
- exfoliative alopecia
- dogs: exfoliative dermatitis, inflammation, hyperaesthesia
- cats: *long-haired breeds, similar signs esp. on head/trunk
Cheyletiella diagnosis:
skin scrape
Cheyletiella treatment:
avermectins, acaricide shampoos
Pneumonyssoides canis host:
dogs
Pneumonyssoides canis life cycle:
- all stages in sinuses, superficial
- not fully understood
- ~3 weeks
Clinical signs associated with Pneumonyssoides canis:
rhinitis, hyperemic mucosa
How do you diagnose Pneumonyssoides canis?
rhinoscopy; nasal swabs
Pneumonyssoides canis tx:
mainly avermectins
