Pruritic ectoparasitic disease Flashcards
Ectoparasites other than fleas
Pediculosis
- louse infestation
- uncommon in dogs and cats
- Felicola sp (cat): chewing/biting
- Trichodectes canis (dog): chewing/biting
- Linognathus setosus (dog): sucking
Pediculosis: surface, burrowing or deep?
- surface
Pediculosis: Brief life cycle summary
Whole life cycle on host -> easy to kill
Can live off host?
- Adults survive 3 days only
- May have nits in bedding -> indirect infestation
Pediculosis: host specific?
- yes
Pediculosis: contagious?
- yes
Pediculosis: zoonotic?
- no
Pediculosis: classical clinical signs
- Often asymptomatic
- may see: poor coat, scaling, papules, crusts, variable pruritus
- Heavy infestation may -> anaemia, lethargy
Pediculosis: dx
- Coat combing/brush
- Hair plucks for eggs?
Pediculosis: importance
- Uncommon
- Dz of debilitation
Pediculosis: tx
- Relatively easy as life-cycle entirely on host
- Many flea adulticides effective, e.g. imidacloprid, fipronil, selamectin – all licensed, isoxazolines - not licensed but likely effective
- Treat in-contacts also
- Environmental cleaning recommended
Arachnids
- Sarcoptic mange (dog)
- Cheyletiellosis (dog, cat)
- Otodectes (dog, cat)
- Neotrombicula autumnal (dog, cat)
- Canine demodicosis
- Feline demodicosis
Sarcoptic mange: parasite name
- Sarcoptes scabiei var. canis
- Round mite, 8 short legs
Sarcoptic mange: Surface/burrowing/deep?
- Burrow in stratum corneum
Sarcoptic mange: Brief life cycle summary
- Where lifecycle occurs: on host
- Can survive off host? Yes. – How long? 1-2 days
Sarcoptic mange: Host-specific?
- Wildlife reservoir = Fox
Sarcoptic mange: Contagious?
- Yes, highly
Sarcoptic mange: Zoonotic?
- Yes
Sarcoptic mange: Classical clinical signs
- Intense pruritus
- Papules and crusts, esp pinnal margins, elbows, hocks, sternum but other areas also affected
- 80% show pinnal pedal reflex (hindleg scratches when pinnal lesions rubbed) – not 100% specificity
Sarcoptic mange: Diagnostic tests
- Superficial skin scrapings: NB 25-50% sensitivity, high risk false negatives
- IgG serology (ELISA): available but potential for false +ves and false –ves so uncommonly used. NB seroconversion takes 4 weeks so don’t sample too early
- Therapeutic trial justified if disease suspected
Sarcoptic mange: Management
Acaracidal treatment to animals:
- Sarolaner, afoxolaner, fluralaner (ie selected isoxazolines) licensed
- Also selamectin, moxidectin
- Treat in-contacts also
- Treatments very effective but can take several weeks to respond - warn owner
Other actions:
- +/- short course corticosteroids (e.g. prednisolone) or oclacitinib (off label) to control pruritus if needed – NB pruritus may increase as mites die
- Contagious to other dogs: avoid contact
- Decontaminate or destroy fomites such as bedding, brushes
- Treat environment, e.g. environmental flea spray
Zoonotic! - advise owner
Cheyletiellosis: Parasite name
- Cheyletiella spp
- Heart-shaped body, 8 long legs
- Accessory mouthparts terminate in prominent hooks
- Other spp of this genus affects rabbits
Cheyletiellosis: Surface/burrowing/deep?
- Surface
Cheyletiellosis: Brief life cycle summary
- Where lifecycle occurs: on host
- Can live/survive off host? Yes
Cheyletiellosis: Host-specific?
- No
Cheyletiellosis: Contagious?
- Yes, very
Cheyletiellosis: Zoonotic?
- Yes
Cheyletiellosis: Classical clinical signs
- Pruritus and scale, esp dorsal trunk
Cheyletiellosis: Diagnostic tests
- Superficial skin scraping
- Microscopy of scale from combing – in LP under coverslip
- Unstained acetate tape strip on skin
- Trichogram for eggs
- NB False negatives common so trial treat if suspect
Cheyletiellosis: Management in dogs/cats
- Often difficult to eradicate as can survive off host
- Treat affected animal and in-contacts
- Currently no licensed products but effective acaricides include: Isoxazolines, Selamectin, Moxidectin
- Clean environment and treat with environmental flea spray
Otocariasis: Parasite name
- Octodectes cynotis
- ear mites
- 8 long legs
Otocariasis: Surface/burrowing/deep?
- Surface
Otocariasis: Brief life cycle summary
Where lifecycle occurs: In ears (but can also be reservoir on other areas of body)
Can live off host? Yes for 5-17d
Otocariasis: Host-specific?
- No
Otocariasis: Contagious?
- Yes
Otocariasis: Zoonotic?
- No
Otocariasis: Classical clinical signs
- Ear irritation, head shaking
- Excessive ear wax
- Occasional irritation of face, body
Otocariasis: Diagnostic tests
- See mites on otoscopy
- See mites/eggs on microscopy of cerumen
Otocariasis: tx
Systemic therapy
- preferable to topicals, as mites may be harboured on other areas of body (not just in ears)
- Selected isoxazolines licensed – containing sarolaner, fluralaner, afoxolaner, tigolaner
- Also selamectin, moxidectin
Topical therapy – rarely used, compliance difficult
- Acaricidal ear drops twice daily for three weeks, as eggs unaffected
NB Surolan/Aurimic and Canaural (polypharmacy ear products)
- licensed but contain no anthelmintic Contain antibiotic - poor antibiotic stewardship to use for mites
Harvest mite infestation: Parasite name
- Neotrombicula autumnalis
- Orange parasite
- Visible to naked eye
- 6 long legs, 2 body parts = larva
Harvest mite infestation: Surface/burrowing/deep?
- Surface
Harvest mite infestation: Brief life cycle summary
Where lifecycle occurs:
- Occur seasonally (summer/autumn) and in certain geographical areas only. Nymphs and adults on ground (free-living). Only larva parasitic.
Can live off host?
- Yes
Harvest mite infestation: Host-specific?
- No
- Affects dogs, cats, occasionally humans
Harvest mite infestation: Contagious?
- Not directly between animals
Harvest mite infestation: Zoonotic?
- No, but people can be infested from larvae on ground too
Harvest mite infestation: Classical clinical signs
- Papules, crusts, pruritus
- Especially interdigital spaces, pinnae (Henry’s pocket), ventral abdomen
Harvest mite infestation: Diagnostic tests
- See as orange dots with naked eye
- Superficial skin scrape into liquid paraffin if microscopy needed
Harvest mite infestation: tx
- No licensed products
- Various products used e.g.
– Fipronil spray every 2 weeks
– Selamectin spot-on
– Isoxazolines – likely effective but not licensed
Canine demodicosis parasites
- D. canis: common, variably pruritic
- D. injai: less common, highly pruritic, extra long-bodied mite
D. injai: Surface/burrowing/deep?
- Deep – follicular mite
D. injai: Brief life cycle summary
- As per D canis, but D injai often affects adult dogs
- Where lifecycle occurs: Whole life cycle on host
- Can live/survive off host? No
D. injai: Host-specific?
- Yes
D. injai: Contagious?
- No
D. injai: Zoonotic?
- No
D. injai: Classical clinical signs
- Intense pruritus especially face + dorsum, often greasy coat, +/- mild hair loss
- Terriers predisposed
D. injai: Diagnostic tests
- Deep skin scrapings – multiple
- Hair plucks
D. injai: tx
- As per D canis + investigate underlying cause
- No need to tx in-contacts or environment
Feline demodicosis: parasites
- uncommon
- D cati: long slender mite (like D canis)
- D gatoi: smaller than D cats, broad short abdomen
Feline demodicosis: Surface/burrowing/deep
- D cati: Deep- follicular mite
- D gatoi: In superficial stratum corneum
Feline demodicosis: Brief life cycle summary
- D cati:
– Life cycle/pathogenesis as D canis – may be secondary to FeLV/FIV, other immunosuppressive conditions
–Can live off host? No - D gatoi:
– Non-follicular mite. Life cycle otherwise as D canis
– Can live off host? No
Feline demodicosis: Host-specific?
- D cati: yes
- D gatoi: yes
Feline demodicosis: Contagious?
- D cati: No
- D gatoi: Yes- in contacts may be asymptomatic
Feline demodicosis: Zoonotic?
- D cati: no
- D gatoi: no
Feline demodicosis: Classical clinical signs
- D cati: Erythema, papules, pustules, alopecia (as D canis)
- D gatoi: Over-grooming -> self-induced alopecia
Feline demodicosis: Diagnostic tests
- D cati:
– Deep skin scrapes (multiple – use x4 objective)
– Hair plucks - D gatoi:
– Superficial skin scrapes from areas inaccessible to tongue – need x10 objective
– Tape strips?
– Faecal exam for ingested mites?
– Check in-contacts?
– Hard to detect so trial treat if suspect
Feline demodicosis: tx
- For both
- Localised form: may be self limiting
- Generalised form:
– No licensed products
– Individual/anecdotal case reports for some isoxazolines
->Sarolaner (in Stronghold Plus), fluralaner (Bravecto spot-on) (licensed for cats for fleas/ticks and Demodex in dogs) - Need to address and correct underlying cause if possible
- NB D gatoi: need to treat in-contacts also