Lecture 18 4/22/24

Question 1

What are the general characteristics of arthropods?

Answer 1

-coelomates
-bilaterally symmetrical
-cephalization/formation of head
-segmented, with jointed appendages
-continuous chitinous exoskeleton
-open circulatory system

Question 2

What are the general characteristics of arachnids?

Answer 2

-have piercing mouthparts instead of mandibles
-cephalothorax (fused head and thorax) and abdomen sections
-no antennae
-simple eyes
-4 pairs of legs in nymphs/adults, 3 pairs in larvae
-mostly terrestrial
-life cycle is egg, larva, nymph, adult

Question 3

What are the characteristics of the subclass Acari?

Answer 3

-head, thorax, and abdomen fused in one body
-most are free-living
-parasitic forms feed by puncturing tissues and sucking juices/blood
-females usually die after laying eggs

Question 4

What are the general characteristics of ticks?

Answer 4

-grossly visible
-obligate parasites
-important vectors of pathogens
-broad taste in potential host
-hypostome with teeth
-possess Haller’s sensory organ

Question 5

What are the general characteristics of mites?

Answer 5

-often microscopic
-many life strategies
-rarely vectors of pathogens
-host specific
-hypostome without teeth
-lack Haller’s sensory organ

Question 6

How are mites diagnosed?

Answer 6

-collection and identification
-capture with comb/brush
-skin scrapings and crusts
-skin biopsies
-fecal
-fixed in 70% alcohol for ID

Question 7

What are the characteristics of Dermanyssus gallinae?

Answer 7

-red fowl mite of all birds
-can cause severe bites on humans and other animals
-nocturnal
-hide in cracks/crevices during the day

Question 8

How can Dermanyssus gallinae be controlled/treated?

Answer 8

-heat tree limbs before using as perches
-remove perches during daylight
-supportive care

Question 9

What are the characteristics of Ornithonyssus bacoti?

Answer 9

-tropical rat mite
-aggressive blood feeder
-will attack humans and other animals
-can be an issue for pet rodents

Question 10

What are the characteristics of family Trombiculidae/chiggers?

Answer 10

-adults and nymphs are free living
-larvae are the chiggers
-ectoparasite of humans and animals
-firmly attach and digest a long tunnel through the dermis
-severe irritation and dermatitis after infestation

Question 11

What are the characteristics of Sarcoptes scabiei?

Answer 11

causes sarcoptic mange and human scabies
-parasite of both animals and humans
-different strains on different animals
-larvae and nymphs come to surface of skin and are transferred to other hosts through contact
-occur where hair coat is thin and skin is tender
-very pruritic lesions
-deep skin scrape for ID

Question 12

How do adults of Sarcoptes scabiei appear?

Answer 12

-oval with rounded, short mouthparts
-tarsal suckers on long, unjointed pedicels
-burrowed into skin

Question 13

What is the lesion distribution for Sarcoptes scabiei var. bovis?

Answer 13

-lower neck
-rear
-inner thigh
-tail root

*REPORTABLE

Question 14

What is the lesion distribution for Sarcoptes scabiei var. canis?

Answer 14

-face
-pinnae
-around eyes
-chest
-elbows
-abdomen
-spreads to other regions

Question 15

What is the legion distribution for Sarcoptes scabiei var. suis?

Answer 15

-neck
-shoulders
-eyes
-ears
-snout
-tail root

Question 16

What are the characteristics of Notoedres cati?

Answer 16

-seen in cats and rabbits
-adults resemble S. scabiei
-lack dorsal spines
-slightly smaller and more round in shape
-burrows into skin
-starts at tips of ears and spreads to face, head, and paws
-transmitted by contact
-easier to find on skin scrape than S. scabiei

Question 17

What are the characteristics of Psoroptes cuniculi?

Answer 17

-rabbit ear mite
-long, sharp mouthparts
-legs 3 and 4 extend beyond body margins
-tarsal suckers on long, jointed pedicels

Question 18

What are the characteristics of Psoroptes ovis?

Answer 18

-sheep scab mite
-reportable and quarantinable
-devastating to sheep
-also infects cattle and horses

Question 19

What is the main difference between Sarcoptes and Psoroptes?

Answer 19

-Sarcoptes has an unjointed pedicel
-Psoroptes has a jointed pedicel

Question 20

What are the characteristics of Chorioptes bovis?

Answer 20

-foot, leg, tail, and scrotal mange
-found in cattle, sheep, goats, horses, rabbits, and camelids
-decreases semen quality
-increases testicular temp.
-long legs
-large tarsal suckers on short, unjointed pedicels
-compressed dorso-ventrally

Question 21

What are the characteristics of Otodectes cynotis?

Answer 21

-ear mites
-found in dogs, cats, ferrets
-direct contact transmission
-extremely contagious
-common, esp. in young animals

Question 22

What are the clinical signs of ear mites?

Answer 22

-brown debris in ear
-ear scratching
-head shaking
-circling and head tilt

Question 23

What is the pathogenesis of Otodectes cynotis?

Answer 23

-live deep in external ear canals
-typically bilateral
-canals become excessively moist
-cerumen and purulent blackish exudates form
-self trauma from scratching can cause aural hematoma and infections; can progress to convulsions

Question 24

What are the characteristics of Demodex?

Answer 24

-aka red mange
-found at base of hairs
-easy to find
-host-specific
-cigar/alligator shape
-normal skin flora

Question 25

What are the two forms of Demodex pathology?

Answer 25

-local
-generalized

Question 26

How is Demodex diagnosed?

Answer 26

skin scraping

Question 27

How is Demodex treated?

Answer 27

dogs and cats:
-acaricide
-antibiotics for secondary bact. infections
cattle:
-self-limiting; not treated

Question 28

What is the pathogenesis of Demodex?

Answer 28

-overpopulation of mites leads to folliculitis and furunculosis
-mites puncture epithelial cells lining hair follicles and glands to feed on contents
-typically seen in immunocompromised individuals

Question 29

Which species primarily suffers from Demodectic mange?

Answer 29

dogs

Question 30

What are the characteristics of localized Demodectic mange?

Answer 30

-seen in young animals; recover with maturation
-small, well defined lesions
-usually on face
-can see alopecia and erythema
-NOT pruritic
-good prognosis
-spontaneous recovery in most cases; no treatment needed

Question 31

What are the characteristics of generalized Demodectic mange?

Answer 31

-affects all ages
-both juvenile and adult onset cases should be neutered/spayed once better to decrease risk of reoccurrence
-very serious disease covering large areas; typically see lesion coalescence
-pyoderma, edema, and pruritis common; secondary infection
-prognosis poor without aggressive treatment
-treated with antibiotics for pyoderma and parasiticides

Question 32

What are the characteristics of Cheyletiella?

Answer 32

-“walking dandruff”
-large mites
-seen in dogs, cats, rabbits
-species specific
-found on fur and in keratin layer of skin
-clinical signs include alopecia and pruritis
-diagnosed through comb & collect or tape preparation
-must treat both host and environment

Question 33

What are the characteristics of Pneumonyssoides caninum?

Answer 33

-nasal mite in dogs
-found in nasal sinuses
-relatively nonpathogenic
-can cause increased nasal secretions and rhinitis
-hyperemia of nasal mucosa

Question 34

How is Pneumonyssoides diagnosed and treated?

Answer 34

-rhinoscopy
-nasal swabs
-avermectins