Parasitic skin disease Flashcards
Insects we’re concerned about?
- FLEAS - Ctenocephalides felis (teno cepha lideesssssss)
- Ctenocephalides canis (MOST COMMON ON DOGS AND CATS)
- Spillpsyllus cuniculi
- LICE
- INSECT BITE HYPERSENSITIVITIES
Discuss flea allergic dermatitis?
- Most common skin disease of dogs and cats in the world
- Zoonotic!
- Pruritic dermatosis
- Pruritus associated with hypersensitivity to salivary proteins of flea (Type I or Type IV)
- Leads to self trauma by pet
- Infestation vs hypersensitivity
- Other pets may be infested but show no clinical signs (cats infested but not itch very much)
- Client communication important
- Important animal can be infesrted with fleas without itching
What is this a classic pattern of?
Clinical signs of FAD in the dog
Distibution of this problem is classic: Caudal and dorsal
Other clinical signs include:
- Scratching
- Biting skin
- Jumping up suddenly
- Excess licking/over grooming
- Results in secondary changes:
- Alopecia
- Skin inflammation +/- skin infection
- Crusting
- Lichenification
Environmental atopy generally feet and face.
Clinical signs of FAD in cat -variable presentations include?
- Miliary dermatitis (tiny crusty scabs over body)
- Alopecia - due to overgrooming
- Eosinophilic granuloma complex lesions (seen in pic) (eosinophilic plaques, eosinophilic granulomas (including ‘fat chins’), indolent (‘rodent’) ulcers)
- Head & neck pruritus
NB These are cutaneous reaction patterns - occur for many reasons in the cat, eg FAD, food-induced or environmental-induced atopic dermatitis. Remember to rule out fleas early on when you see any of these presentations!
What should the clinical approach to FAD in dog or cat be?
- Thorough history-taking (has it got parasites has it got allergy has it got infection?)
- Observation of clinical signs
- Consider differential diagnoses
- Other ectoparasites eg scabies, cheyletiellosis, (Otodectes? Lice?)
- Atopy to environmental or dietary allergens (food allergy, cutaneous adverse food reaction)
- Microbial infections – bacteria, Malassezia
What diagnostic techniques can be used to identify flea infestation?
Demonstration of fleas/flea faeces
- Flea comb
- Vigorous coat brushing – examine debris on moistened paper –> red/brown tinge
- Microscopy of flea dirt collected on combing or tape strip
- Knock down flea spray (eg permethrin on dogs) to kill fleas quickly for demonstration?
- Examine faeces for tape worm segments? If dog has tapeworm likely to have fleas as well!
- (Dipylidium caninum)
But
- False negatives common
- Cats may remove all evidence of fleas from their coat, particularly if flea allergic
- Therefore failure to detect fleas, i.e. negative finding, is unreliable!
- NB Frequently, owners are convinced their pet doesn’t have fleas à communication challenge!
- Because it is a type 1 hypersensitivity and Intradermal allergy test can be done
Response to Therapy
- This is the best method of diagnosis
- Range of effective and ineffective products – chose an effective one!
- Diagnosis is confirmed by response to thorough flea control trial
What advice re flea control would you give to:
The owner of a 5 year old labrador which receives twice weekly bathing for Malassezia dermatitis. The owner also wishes to treat ticks?
Sarolaner, alfaxolaner, flurolaner any of the isoxazalines
What advice re flea control would you give to:
The owner of cat in a multicat household with flea allergic dermatitis?
IGR, Imidacloprid, flumethrin, spinosad and isoxasoline, selamectin and sarolaner
What advice re flea control would you give to:
The owner of a cat with ear mite (Otodectes) and flea infestations?
Selamectin, Imidacloprid and moxidectin, sarolaner
What advice re flea control would you give to:
The owner of a 5 week old kitten with fleas?
Firponil spray (only thing licensed in that age)
Outline the lifecycle of a cat flea?
Series of moults before they become a pupae
Can take up to 140 days for a pupae to hatch to an adult flea
Pupae uneffected by ectoparitisde so need something to kill them in environment such as permethrin in environment as they hatch out
- Flea life cycle usually complete in 3 to 4 weeks but may be as short as 2 weeks or as slow as 6 months, depending on environmental conditions
- Remember the ‘pupal window’…nothing kills the pupae so need to kill emergent adults before they bite – environmental control essential! May take 3 months+ before fleas fully eliminated
- ensure your client is aware of this
Outline the actions of different flea treatments?
Name an insect growth regulator available in an injectable form for cats and an oral form for dogs. Does this product also act as an adulticide?
Lufenuron available as tablet in dogs injection for cats lasts 6 months (no adulticide action)
Name a spot-on product where the pro-drug is activated by the parasite only?
Indoxocarb
Name a spot-on product that kills fleas and sarcoptic mange but has no action against demodicosis?
Selamectin
Name a flea adulticide that will not lose its efficacy with repeated bathing?
Spinosad and isoxasalines
Name a very short-acting (24h) knock-down adulticide?
Nitenpyram
Name an oral product that is active against fleas and ticks (and likely demodicosis –off label) and lasts for 3 months?
Flurolaner
Name lice that infect cats and dogs?
Louse infestation ‘pediculosis’
Dogs
- Trichodectes canis (biting louse) If chewing biting louse on dog it will be this
- Linognathus setosus (sucking louse)
Cats
- Felicola subrostratus
Name some particulars of lice?
- Host specific
- No risk to owners
- Surface parasites, may move quickly
- Operculate eggs ‘nits’ attached to hairs
- Life cycle lasts approx 3 weeks
- Adults can only survive off host for 3 days
- Nits can cause indirect infestation from bedding and blankets, especially if large numbers of dogs
What are the clinical signs of lice?
- Often asymptomatic – may see poor coat, scaling, papules, crusts, variable pruritus
- Heavy infestation can cause anaemia and lethargy
- Infestation may reflect poor hygiene/nutrition/immunity
- Pediculosis (infestation with lice) suspected in this puppy – how will you diagnose it?
How are lice diagnosed?
- Demonstration of lice/eggs with magnifying glass or under microscope
- Combing
- Unstained acetate tape strip
- Hair plucking? Need to pluck the right hair!
How is a lice infestation treated?
Relatively easy to treat as life-cycle entirely on host
- Many flea adulticides effective (eg imidacloprid, fipronil, selamectin, permethrin)
- Treat in-contacts also
- Environmental cleaning recommended
What is seen here and what is the treatment?
Insect bite hypersensitivity
Treatment
- Avoid outdoors especially dawn and dusk
- Use insect repellents (seresto collar = flumethrin and imidaclopid)
- Symptomatic treatment e.g. glucocorticoids, antihistamines
What is this?
Trichodectes canis
What is this?
Demodex canis
What is this?
Sarcoptes scabei
What is this?
Eggs: operculate eggs are lice so no operculation here so cheyletiella mite eggs are seen
What is this?
Cheyletiella (heart shaped)
What is this?
Trombicular (harvest mite)
Name arachnids that can bother animals?
SURFACE MITES
- Cheyletiella (dogs, cats and rabbits and very contagious , 3 week lifecycle can survive off host 3-6 weeks)
- Otodectes
- Neotrombicula
- Sarcoptes (can take 2 months for itch to stop once treatment has started)
DEEP MITES
- Demodex
TICKS
Discuss the surface mite cheylietella?
- Causes cheyletiellosis in dogs, cats, rabbits – highly contagious
- Mite lives on skin surface
- Life cycle takes
- 3-4 weeks
- May survive off host
- 5-6 weeks
- Zoonotic! Humans often affected, with pruritic papules on arms, legs, trunk
Clinical signs
- Pruritus and scaling, especially dorsal trunk – ‘walking dandruff’
- D/d: flea infestation, scabies, atopy
What can manage cheyletiellosis in cats and dogs?
- Often difficult to eradicate as can survive off host
- Currently no licensed products but effective acaricides include:
TOPICAL
- Fipronil (spot-on or spray) every 3-4 weeks
- Selenium sulphide shampoo – weekly
- (Amitraz every 2 weeks x 3 – rarely used. Not cats)
SYSTEMIC
- Selamectin spot-on at 2-4 week intervals
- Isoxazolines? Anecdotal reports
And remember to treat the environment….
- Treat environment with a household flea spray to kill mites off host
- Contaminated materials must be burnt, steam cleaned or chemically treated (eg disinfectant)
What is this and what are the clinical signs of an infestation?
Signs of hypersensitivity
- Ear irritation
- Head shaking
- Excessive ear wax
- Occasional irritation of face or body
Diagnosis
- Visualise ear mites by otoscopy
- Detect ear mites/eggs in cerumen
How can you treat and prevent otodectes cynotis infection?
Treatment and prevention
- TOPICAL THERAPY, in ears Acaricidal ear drops at least twice daily for three weeks, as eggs resistant
- Surolan and Canaural licensed but contain no anthelmintic! Questionable antibiotic stewardship…
- Consider compliance of frequent application
SYSTEMIC THERAPY preferential to the above as it isn’t over use of the above which contain antibiotics
- eg selamectin, moxidectin spot-ons
- sarolaner – licensed
- Note regular ear cleaning important to remove excess cerumen
- Need to treat in-contacts
What is this and what are the clinical signs of infestation?
Sarcoptes scabiei var. canis
- Small burrowing mite
- Life cycle complete in 3 weeks
- Causes sarcoptic mange (scabies) in dogs and foxes
- Highly contagious
- Hypersensitivity to mites may develop
- Zoonotic! Human involvement can occur especially if close contact (bed sharing with dogs!)
Clinical Signs
- Intensely pruritic !! No response to steroids
- 80% show positive pinnal-pedal scratch reflex
- Papules and crusts esp pinnal margins, elbows, hocks, sternum, but other areas may be affected
How do you diagnose Sarcoptes scabiei var. canis?
Diagnosis
History
- Acute-onset intense pruritus is suggestive
- May be unresponsive to prednisolone – NB!
Skin scrapings
- Take multiple skin scrapes (minimum of 6) as difficult to detect (only 50% sensitivity!!)
- Choose primary lesions (crusted papules) in affected areas, avoiding secondary changes
- Look for mites, eggs and even mite faeces
- Use liquid paraffin and cover slip
Serology
- Elisa test available – detects anti-Sarcoptes IgGHighly sensitive and specific
- But can have false positive due to cross-reaction with antibodies to house dust mites in environmental atopic dogs
- Occasional false negatives
- NB Seroconversion takes 3-4 weeks so false negatives are possible if sampled too early
Therapeutic Trial
- Can be used to aid diagnosis particularly if no mites detected – if you suspect sarcoptic mange, treat it!
- Also helps distinguish from atopic dermatitis (can get false positives on serology in dogs sensitised to housedust mites as a cross reactivity)
What are the topical and systemic treatments for sarcoptes?
Systemic
- Selamectin or moxidectin (as moxidectin/imidocloprid) spot-on.
- Sarolaner (Simparica) An isoxazoline
Topical
- Amitraz (solution) applied weekly for 4 weeks+
Toxicity concerns for pet and in-contact people and animals – read instructions carefully and ensure client understands and complies
- Lime sulphur – applied weekly for 4 weeks
Effective & well tolerated but staining & pungent odour
How should a sarcoptic mange infestation be managed?
- Zoonotic, as well as contagious to other dogs so avoid contact and decontaminate or destroy items such as bedding, brushes.
- Treat all in-contact animals with acaricide
- Environmental - insecticidal spray recommended (e.g. flea spray)
- Glucocorticoids, eg prednisolone, to help control intense pruritus (pruritus may increase as mites die)
Compare sarcoptes and demodex mite infestation?
Discuss demodex canis?
- A normal inhabitant of canine skin
- Causes disease in immunocompromised animals
- Not contagious – passed from dam to offspring in first few days of life
- Incapable of living off host
- Excessive multiplication in hair follicles and sebaceous glands –> follicular disease on skin –> folliculitis, alopecia, furunculosis, often with erythema
Discuss demodicosis adult and juvenille onset?
Juvenile: 1-12mo (esp 3-6mo); usually resolve with sexual maturity if localised
- Multifactorial disease: affected by genetics, nutrition, stress, breed
- Avoid breeding from affected individuals
- Common
Adult-onset: 4yo or more
- Uncommon
- usually secondary to immunosuppression – look! (eg hypoT4, HAC, neoplasia)
- Find cause in 50% cases
- Prognosis guarded if underlying cause cannot be corrected
How can demodicosis be diagnosed?
Diagnosis
- Deep skin scrapes (squeeze before scraping!)
- +/- biopsy (if skin scarred, Shar Pei). May see mites, folliculitis, furunculosis
- +/- plucks (esp face and feet)
What drugs are effective for canine demodicosis?
- Sarolaner
- Amitraz (Aludex) (atipam is apparently antidote)
- 10% Imidacloprid/2.5% moxidectin spot-on (e.g. Advocate)
For all cases of demodicosis you should?
- Treat secondary microbial infection, if present
- Glucocorticoids and oclacitanib contraindicated!
- Investigate/correct underlying cause, if possible
- Relapses common – warn owner. Especially at oestrus – neuter when able
- NB avoid future glucocorticoids/oclacitanib if possible \Immunosuppressive drugs just make it worse
- Do not breed from affected animals
What is this?
Feline demodicosis
D. cati (follicular, long and slender mite)
- Uncommon
- Parasite in follicles, sebaceous glands
- –>Localised or generalised disease. +/- waxy otitis externa
- Causes patchy alopecia, erythema, scale. Also may have comedones and secondary pyoderma
- Pruritus variable
- Localised: often head/neck
- Generalised: usually associated with underlying immunosuppression eg FIV, FeLV, diabetes mellitus – check!
What is the treatment for ticks?
Treatment
- Manual removal
- Acaricides
Permethrin, flumethrin, fipronil, deltamethrin, moxidectin, amitraz
- New treatments – fluralaner, afoxolaner, sarolaner
Do not necessarily prevent attachment, but ticks die and drop off within 12-48 hours
Repellants
- Permethrin repels but toxic to cats
- Imidacloprid/flumethrin collar (Seresto collar) – kills and repels for 8 months
Outline tick treatments?
