6.3 Mites

Question 1

what are the 4 general “types” of mites

Answer 1

• itch and mange mites
• bloodsucking mites
• respiratory mites
• SQ mites

Question 2

what is the lifecycle of all mites

Answer 2

simple metamorphosis (egg -> larvae -> nymph -> adult)

Question 3

are mites host-specific or cosmopolitan and why

Answer 3

specific; they complete their entire lifecycle on one host

Question 4

what do mites feed on

Answer 4

hair, fur, skin, secretions

Question 5

What is the name of the sarcoptic mange mite or itch mite

Answer 5

Sarcoptes scabiei

Question 6

where does Sarcoptes scabiei live

Answer 6

in the stratum corneum (superficial layers of skin)

Question 7

What is the morphology of Sarcoptes scabiei (how do you ID)

Answer 7

short-legged, long and unsegmented pedicels, spines on the dorsum, dorsoventrally flattened

Question 8

is Sarcoptes scabiei a commensal mite?

Answer 8

No

Question 9

how is Sarcoptes scabiei transmitted

Answer 9

direct contact

Question 10

what is the pathogenesis of scabies/sarcoptic mange

Answer 10

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

Question 11

what are the predilection sites of Sarcoptes scabiei

Answer 11

areas where the animal cannot scratch: head, ears, elbows, hocks, ventral body, eyes, inner thighs

Question 12

how should you treat Sarcoptes scabiei

Answer 12

clip hair, remove crusty material, endectocides

Question 13

is Demodex a commensal or primary pathogen

Answer 13

commensal

Question 14

where is demodex infecting

Answer 14

hair follicles, sebaceous glands, apocrine glands

Question 15

What is the morphology of Demodex

Answer 15

elongate, stubby and worm-like

Question 16

how is Demodex transmitted

Answer 16

direct contact, prolonged

Question 17

What is the pathogenesis of Demodex in ruminants

Answer 17

forms pinhead to egg-sized nodules filled with pus and mites

Question 18

What is the pathogenesis of demodicosis in dogs

Answer 18

Not fully understood since normal flora; localized and generalized forms of the disease

Question 19

what is localized demodicosis related to

Answer 19

stress and hereditary predisposition

Question 20

what does localized demodicosis look like

Answer 20

few small lesions with some hair loss and scaling that heals spontaneously

Question 21

how does generalized demodicosis look

Answer 21

scaling, alopecia and erythema, rupture of follicles with secondary disease giving rise to systemic signs

Question 22

How do we diagnose demodicosis in:
- ruminants
- dogs

Answer 22

ruminants: examine contents of nodules

dogs: deep skin scrapings or hair plucks

Question 23

how do you treat demodicosis

Answer 23

localized: no treatment usually needed

generalized: Amitraz, moxidectin, ivermectin

Question 24

what is the name of the ear mite

Answer 24

Otodectes cynotis

Question 25

where is otodectes located

Answer 25

ear canal and adjacent skin of a single host

Question 26

how can you ID otodectes

Answer 26

long legs, short, unsegmented pretarsi, large sucker

Question 27

how is otodectes transmitted

Answer 27

direct contact

Question 28

what does otodectes cynotis cause

Answer 28

dermatitis, pruritis, dark exudate from the ear

Question 29

how do you treat otodectes

Answer 29

clean ear thoroughly and instill a topical acaracide into the ear canal; can use moxidectin and salamectin among others

Question 30

what is the name of the fur mite

Answer 30

Cheyletiella spp.

Question 31

how can you ID Cheyletiella spp.

Answer 31

larger, long palps that look like a 5th pair of legs, long legs

Question 32

where is Cheyletiella living and what does it feed on

Answer 32

under the dead layers of skin, feeds on the epidermal debris

Question 33

how is Cheyletiella transmitted

Answer 33

direct contact

Question 34

what does Cheyletiella cause

Answer 34

a greasy coat, usually non-pruritic

Question 35

Is Cheyletiella normally seen in older or younger dogs

Answer 35

older

Question 36

what species is Chorioptes present in

Answer 36

ruminants and horses

Question 37

how do you ID Chorioptes

Answer 37

long legs, short unsegmented pedicels with large suckers Looks exactly like otodectes so you ID based on location and species

Question 38

what are the lesions caused by Chorioptes

Answer 38

small lesions that may coalesce, usually no lesions in sheep, pruritis and more extensive lesions in horses and pruritic disease in cattle

Question 39

when do we tend to see Chorioptic mange in cattle and why

Answer 39

in the winter; stressed and housed together in direct contact

Question 40

what are the scab mites

Answer 40

Psoroptes

Question 41

how do you ID Psoroptes

Answer 41

long legs, long, segmented pedicels with small suckers

Question 42

what are the lesions caused by Psoroptes

Answer 42

inflammation and hypersensitivity, papules and thickening of skin, pruritis and self-inflicted alopecia

Question 43

Why does Psoroptes cause intense inflammatory and pruritic disease

Answer 43

It mites by piercing the skin which injects saliva into the living layer of epidermis