6.3 Mites Flashcards
what are the 4 general “types” of mites
- itch and mange mites
- bloodsucking mites
- respiratory mites
- SQ mites
what is the lifecycle of all mites
simple metamorphosis (egg -> larvae -> nymph -> adult)
are mites host-specific or cosmopolitan and why
specific; they complete their entire lifecycle on one host
what do mites feed on
hair, fur, skin, secretions
What is the name of the sarcoptic mange mite or itch mite
Sarcoptes scabiei
where does Sarcoptes scabiei live
in the stratum corneum (superficial layers of skin)
What is the morphology of Sarcoptes scabiei (how do you ID)
short-legged, long and unsegmented pedicels, spines on the dorsum, dorsoventrally flattened
is Sarcoptes scabiei a commensal mite?
No
how is Sarcoptes scabiei transmitted
direct contact
what is the pathogenesis of scabies/sarcoptic mange
secretions and excretions of the mites cause hypersensitivity; self-inflicted damage leads to hair loss, bleeding and scabbing; secondary infections; emaciation and death; inflammation causes thickened, dry, scaly skin
what are the predilection sites of Sarcoptes scabiei
areas where the animal cannot scratch: head, ears, elbows, hocks, ventral body, eyes, inner thighs
how should you treat Sarcoptes scabiei
clip hair, remove crusty material, endectocides
is Demodex a commensal or primary pathogen
commensal
where is demodex infecting
hair follicles, sebaceous glands, apocrine glands
What is the morphology of Demodex
elongate, stubby and worm-like
how is Demodex transmitted
direct contact, prolonged
What is the pathogenesis of Demodex in ruminants
forms pinhead to egg-sized nodules filled with pus and mites
What is the pathogenesis of demodicosis in dogs
Not fully understood since normal flora; localized and generalized forms of the disease
what is localized demodicosis related to
stress and hereditary predisposition
what does localized demodicosis look like
few small lesions with some hair loss and scaling that heals spontaneously
how does generalized demodicosis look
scaling, alopecia and erythema, rupture of follicles with secondary disease giving rise to systemic signs
How do we diagnose demodicosis in:
- ruminants
- dogs
ruminants: examine contents of nodules
dogs: deep skin scrapings or hair plucks
how do you treat demodicosis
localized: no treatment usually needed
generalized: Amitraz, moxidectin, ivermectin
what is the name of the ear mite
Otodectes cynotis
where is otodectes located
ear canal and adjacent skin of a single host
how can you ID otodectes
long legs, short, unsegmented pretarsi, large sucker
how is otodectes transmitted
direct contact
what does otodectes cynotis cause
dermatitis, pruritis, dark exudate from the ear
how do you treat otodectes
clean ear thoroughly and instill a topical acaracide into the ear canal; can use moxidectin and salamectin among others
what is the name of the fur mite
Cheyletiella spp.
how can you ID Cheyletiella spp.
larger, long palps that look like a 5th pair of legs, long legs
where is Cheyletiella living and what does it feed on
under the dead layers of skin, feeds on the epidermal debris
how is Cheyletiella transmitted
direct contact
what does Cheyletiella cause
a greasy coat, usually non-pruritic
Is Cheyletiella normally seen in older or younger dogs
older
what species is Chorioptes present in
ruminants and horses
how do you ID Chorioptes
long legs, short unsegmented pedicels with large suckers
Looks exactly like otodectes so you ID based on location and species
what are the lesions caused by Chorioptes
small lesions that may coalesce, usually no lesions in sheep, pruritis and more extensive lesions in horses and pruritic disease in cattle
when do we tend to see Chorioptic mange in cattle and why
in the winter; stressed and housed together in direct contact
what are the scab mites
Psoroptes
how do you ID Psoroptes
long legs, long, segmented pedicels with small suckers
what are the lesions caused by Psoroptes
inflammation and hypersensitivity, papules and thickening of skin, pruritis and self-inflicted alopecia
Why does Psoroptes cause intense inflammatory and pruritic disease
It mites by piercing the skin which injects saliva into the living layer of epidermis
