Dermatology Flashcards
(109 cards)
What are the key clinical impacts of ectoparasites?
Direct impact on host welfare
- esp. parasites causing pruritus & cutaneous myiasis
Predisposition to secondary infections
Vectors of disease
Clinical signs mimic other disease
- e.g. allergic skin disease
Act as pointers to other disease
- E.g. lice may indicate underlying immunocompromise
Zoonotic importance
Economic importance
Give examples of ectoparasites that act as vectors of disease
Ticks can transmit:
- babesiosis (cattle/dogs)
- louping ill (sheep/grouse)
- Echinococcus (hydatidosis) (sheep)
Fleas can transmit:
- Dipylidium caninum (dog)
- myxomatosis (rabbit)
Sandflies can transmit:
- leishmaniasis
Give examples of zoonotic ectoparasites
Sarcoptes, Cheyletiella, fleas
Give an example of an ectoparasite with significant economic importance
Psoroptes ovis (sheep scab)
What are the common clinical signs of ectoparasites on skin surface?
Pruritus –> alopecia +- erosions, crust, scale, secondary bacterial infections, chronic changes
Why may fleas not always be found on an animal?
Most of their life cycle occurs in the environment
What are common ectoparasites on the skin surface?
Fleas
Lice
Surface mites
Which animals are commonly affected by lice?
Farm animals, horses, guinea pigs, birds
Incidence greater when animals housed together – seen esp farm animals/horses in winter
How do lice appear on an animal?
Approx. 3mm long, visible to naked eye, eggs (‘nits’) attached to hairs
Name surface mites in cattle
Chorioptes bovis (common) - tailhead, lower legs, scrotum, udder
Psoroptes (rare)
Name surface mites in sheep
Psoroptes ovis - sheep scab
Chorioptes bovis - scrotal mange
Name surface mites in horses
Chorioptes equi (common) – leg/tail mange, esp horses with ‘feathers’
Psoroptes spp – body + ear mange
Neotrombicula sp (harvest mite) – head/legs – late summer/autumn
Name surface mites in dogs/cats
Otodectes (ear mite) – otitis – dark dry otic exudate
Cheyletiella (fur mite) – truncal scale - zoonotic!
Neotrombicula (harvest mite) – esp head/limbs, late summer/autumn
Name surface mites in rabbits
Cheyletiella (fur mite) – (common) truncal scale - zoonotic!
Leporacus gibbus (fur mite) –often asymptomatic, occ –> lesions – brown mite just visible
Psoroptes cuniculi (ear mite) – painful flakey adherent otic crust
Give examples of ectoparasites below the skin surface
Burrowing (round) mites
Demodex
What clinical signs do burrowing mites cause?
Pruritus, alopecia +- papules, hyperkeratosis, crust
Name a burrowing mite that affects dogs and describe the signs of infestation
Sarcoptes scabiei (zoonotic) causes sarcoptic mange, leading to intense pruritus, crusting on pinnal margins, hocks & elbows, along with a positive pinnal-pedal reflex
What burrowing mite affects guinea pigs and is zoonotic?
Trixacarus – causes extreme pruritus & can lead to seizures/death
What is a common burrowing mite in birds?
Cnemidocoptes (Knemidocoptes) – ‘scaley beak’, ‘scaley leg’
What is Demodex and what clinical signs does it cause?
Follicular mite (lives in hair follicles) causing folliculitis, pustules, comedones, alopecia & furunculosis (deep pyoderma)
Which species are most commonly affected by demodicosis?
Dogs, hamsters & occasionally cats
Associated with underlying immunocompromise – most common in young/elderly animals
What are the clinical impacts of tick infestations?
Can act as disease vectors, cause anaemia with heavy infestations & lead to tick granulomas (if mouthparts retained)
What is cutaneous myiasis, and which animals are most susceptible?
Also known as blowfly strike
Infestation with fly larvae (maggots) that feed on host tissue
Sheep & rabbits particularly susceptible, especially in areas with faecal soiling or wounds
How do flea infestations differ in cats and dogs?
Dogs: Lesions mainly on caudal/dorsal part of body
Cats: Present with 4 cutaneous reaction patterns (head/neck pruritus, symmetrical alopecia, eosinophilic granuloma complex, or miliary dermatitis)