Mites Flashcards
Are mites arachnids?
Yes
How do mites differ from ticks?
- size
- time/location on host
- same life cycle stages
- same aspects of morphology
Mite mouth parts
Have structures that will scrape skin, do not penetrate
- feed on skin secretions, or chew on skin
Acariasis
Mite infestation
- young, old, immunocompromised at risk
- common clinical signs: skin lesions, hair loss, crusty skin
- diagnostics: skin scrape (important to get deep, mite burrow)
Are mites zoonotic?
Yes
Sarcoptes scabiei
Host-adapted variants/strains
- can be zoonotic, humans also have their own variant
- wide range of hosts (canids, swine, ferrets)
- severe disease in red foxes, immunocompromised hosts (crusted scabies)
Does Sarcoptes scabiei affect cats?
No
S. scabiei motile stages
Larvae, nymphal, adult
S. scabiei life cycle
Occurs on host, mostly in epidermis over 2-3 weeks
Sarcoptic mange usually affects ______ areas first
Hairless
- papules, erythema, pruritus = hyperkeratosis, alopecia
- self trauma, secondary infections, crusting
- may be fatal
Dog
Itch mite
- lateral elbows, lateral hocks, edge of pinna
Swine
Ears. back
Cattle
Barn itch
- abdomen, neck, medial hind legs
Sheep/goats
Head scab
- face, ears, ventrum
Horses
Neck, shoulders, face
When is Sarcoptes scabiei reportable?
Sheep, goats, horses
Sarcoptic mange diagnosis
Skin scrapings (deep) - negative scrapings NOT conclusive - PCR History Response to treatment
Sarcoptic mange treatment
Various acaricides
- dips
- avermectins
Notoedres cati
Wild or domestic felids
- lesions begin on ears, face, neck –> feet/perineum
- thick, scaly skin, alopecia, pruitus –> self trauma, systemic
- potentially zoonotic
Is N. cati a problem for rabbits?
Yes, households with cats and rabbits should treat both
Psoroptes cuniculi
Common ear mites
- hosts: rabbits, goats, horses
Psoroptes ovis
Cattle, sheep, horses
- primarily southwest
- reportable
Psoroptes spp. life cycle
Non-burrowing on skin
P. ovis of cattle
Cattle scab
- back, tail head, shoulders
P. ovis of sheep
Neck, back
P. ovis of horses
Base of mane
Psoroptes ovis is reportable in
Cattle, sheep
Chorioptes spp
Most common mite of cattle, horses
- also in small ruminants
- NOT reportable!
- chorioptic mange: mild or no clinical signs
- non-burrowing
Chorioptes in cattle
Foot and tail mange, tail scab
- base of tail, udder, hind feet
Chorioptes in sheep, goats
Foot and tail mange
- interdigital, base of tail, scrotum (sheep)
Chorioptes in horses
Foot mange, itchy leg
- foot, base of tail
- especially occurs in draft breeds
Otodectes cynotis
Dogs, cats, ferrets (is transferable among different animal species)
- common ear mite
- mites in external ear canal
Ear mites
Canals become excessively moist
- inflammation –> pruritus –> self trauma
- secondary infection, ruptured ear drum
- bilateral
Purulent black exudate
Cerumen
Otodectes cynotis - diagnosis
Ear swabs
- all dogs, cats in household need to be treated
Demodex spp.
Most species are normal fauna of skin
- transmission by direct contact (mother) –> neonate
- immunosuppression –> overgrowth –> disease
Which demodex species is a primary pathogen?
D. cornei
Demodex life cycle
All stages develop on host within hair follicle lumen and sebaceous gland ducts
Squamous demodicosis
Localized or generalized
- primarily dogs
- seen in cats, horses, sheep
- dry, scaly dermatitis, alopecia
Papulonodular demodicosis
Cattle, goats, pigs
- hair follicles/glands obstructed –> nodules
Localized demodectic mange in dogs
Small, well-defined patchy lesions
- young (less than 1 year)
- self limiting with spontaneous recovery
Generalized demodectic mange in dogs
Usually underlying disease
- large coalescing lesions (pruritus, secondary infection)
- no age predilection
- poor prognosis if no aggressive treatment
Is demodex pruritic on its own?
No, requires secondary infection
Feline demodectic mange
Rare
- D. cati is normal flora (eyelids, head, neck)
- D. gatoi is transmissible = pruritus, superficial (ventrum limbs) –> is a primary pathogen
Demodectic mange - cattle
Common in pregnant, lactating cows
- nodular, neck, shoulders
Demodectic mange - sheep
Rare
- diffuse, scaly, neck, flank, shoulders
Demodectic mange - goats
Young or pregnant
- nodular, face, neck, axilla, udder
Demodectic mange - horses
Rare, chronic corticosteroids
- diffuse, scaly
Demodectic mange - pigs
Rare
- nodular, snout
Cheyletiella
Dog, cats
- very contagious, potentially zoonotic!
- walking dandruff
- nonburrowing
Cheyletiella clinical signs
- dogs: exfoliative dermatitis, inflammation, hyperaesthesia
- cats: long haired breeds, similar signs as dog on head/trunk
Pneumonyssoides caninum
Dog
- nasal mite!
- rhinitis, hyperemic mucosa
- diagnose via rhinoscopy, nasal swab
Knemidocoptes mutans
Chickens, pet birds
- severe hyperkeratosis
Dermanyssus gallinae
Chickens, wild birds
- anemia: decreased production
Ornithonyssus sylvarium
Chickens, turkeys
- anemia: soiled vent feathers
