Sarcoptes, Otodectes & Demodex

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1 Sarcoptes, Otodectes & Demodex Dr Lee Strapp BVetMed MRCVS Veterinary Scientific Liaison Bayer Animal Health

2 Overview Sarcoptes, Otodectes, Demodex Three different mites, all commonly encountered Obligate parasites - entire life cycle on host Skin disease termed mange: sarcoptic, otodectic or demodectic

3 Sarcoptes

4 Introduction Sarcoptes scabiei var. canis Burrowing mite, found in the lower stratum corneum of the epidermis Relatively common in dogs, foxes, other canidae Very rare in cats (host specific Notoedres cati) Zoonotic; can infest humans Often referred to as Sarcoptic mange / fox mange Known as scabies in human medicine Highly contagious whole household

5 Exclusively on host 2 to 3 weeks Mating on surface Egg laying in burrows Transmission; close contact 1 Egg 4 Tritonymph 2 Larva 5 Adult 3 Protonymph Life Cycle

6 Clinical Signs Pruritus (often intense) Alopecia Erythema Papules Crust Excoriations Secondary pyoderma Pinna-pedal reflex often present Predisposed sites; ears, muzzle & elbows

7 Clinical Lesions

8 Clinical Signs (Chronic) Ongoing pruritus Extensive self trauma Scale Hyperpigmentation Lichenification Untreated can spread to whole body Systemic signs may be seen Lethargy / malaise / inappetance Histopathology Chronic inflamm. / hyperkeratosis / parakeratosis

9 Typical Distribution of Lesions Head Periocular Pinnal margin Ventral abdomen Chest Legs esp. elbows

10 Pinna-Pedal Reflex Rub pinnal margins frantic scratching Common BUT not always seen

11 Sarcoptic Mange in a Puppy

12 Identification Sarcoptes scabiei mites are rotund, ventrally flattened and dorsally convex, with short legs The dorsum is covered in spines and there is a terminal anus

13 Diagnosis 1 Presumptive diagnosis is often made on the basis of history & clinical signs Dermatitis affecting dog & in contact dogs +/- humans Nature and distribution of cutaneous lesions Positive pinna-pedal reflex highly suggestive Pruritus minimally responsive to steroids Similarity with a number of differential diagnoses, aim for a laboratory diagnosis

14 Diagnosis 2 Confirmatory diagnosis by skin scrapings As many as possible; edges of lesions, not from open wounds or chronically inflamed excoriations Preferred locations are those covered in visible raised yellowish crusts and papules Sites of predeliction; edges of ears, elbows and limbs especially around tarsal joint Mites, mite eggs, mite faeces Low sensitivity ~25% confirmed by scrapes

15 Sarcoptes scabiei microscopy 10% potassium hydroxide (KOH) solution can be added to the collected material and then gently warmed to help clear the debris to reveal the mites

16 Sarcoptes egg

17 Diagnosis 3 Serological testing commercial ELISA tests (demonstration of anti Sarcoptes scabiei var canis IgG) sensitivity up to 90% False negatives, as seroconversion can take ~5 weeks Positive results DO NOT indicate active infestation but do indicate prior exposure Time taken to be seronegative - several months + Do not use to declare failure of treatment Histology not usually conclusive, unless find mites themselves by chance

18 Treatment Systemic acaricides 10% imidacloprid / 2.5% moxidectin spot-on 0.1ml/kg, twice 4 weeks apart Selamectin spot-on 6-12mg/kg, twice 30 days apart Topical acaricides Amitraz, weekly sponge on Systemic isoxazolines Sarolaner, twice at monthly intervals

19 Sarcoptic Mange Response To Treatment Before treatment

20 Sarcoptic Mange Response To Treatment 22 days after initial treatment

21 Sarcoptic Mange Response To Treatment 50 days after initial treatment

22 Efficacy of Treatments Both products were highly effective against sarcoptic mange with a parasitological cure rate on Day 56 of 100%. dramatic reduction in the clinical signs associated with sarcoptic mange from the first application. Must treat in-contact animals! Australian Veterinary Journal Vol. 84, February 2006 Fourie et al.

23 Sarcoptic Mange in a Human Severe clinical cases in humans are frequently associated with host adapted S. scabiei var. hominis

24 Otodectes

25 Introduction Otodectes cynotis is the most common mange mite of cats and dogs in the world Over 50% of otitis externa cases in dogs and 85% in cats involve infestations with Otodectes The mites do not burrow; they live on the surface of the skin of the outer ear canal They feed, causing irritation and the canal becomes full of cerumen, blood & mite faeces

26 Life Cycle & Transmission Entire life cycle on host; complete in ~3 weeks Eggs hatch into larval ear mites in ~4 days One larval & two nymphal stages then adult Transmission usually by direct contact: especially from infested dams to their young also from dogs to cats and vice versa Transmission through cerumen expelled from ear during scratching & head shaking is rare Large proportion of cats & dogs harbour a small population of mites

27 Clinical Signs Brown waxy discharge in external ear canal Ear mites may be seen Pinnae & ear canal erythema Mild to severe pruritus physical presence of mites & mite saliva is an irritant +/- Ulceration Signs of secondary trauma Excoriation & wet eczema Head shaking +/- Aural haematoma Tympanic membrane may be perforated» Torticollis / Circling / incoordination

28 Discharge from Otodectes

29 Diagnosis Dark brown to black crumbly crusts or waxy deposits + pruritus highly suggestive Visualisation of mites on direct otoscopic examination (BUT avoid light!) To confirm diagnosis, ceruminous debris removed from ear canal and examined microscopically for mites +/- eggs

30 Otodectes on Microscopy

31 Treatment Ear cleaning products remove ceruminous debris Ear drops applied directly into the ear canal usually twice daily for several days repeat course 7-10 days later is required Topical spot-ons incorporating systemic active ingredients, such as moxidectin or selamectin In some clinical cases, anti-inflammatory medications are used to ease secondary signs

32 Advocate Treatment Do not apply directly to the ear canal Examination 30 days after treatment is recommended as some animals may require a second treatment Efficacy 98-99% Treat in-contacts

33 Demodex

34 Introduction Demodex canis is a common mite of dogs Low numbers - normal part of cutaneous fauna Other Demodex species are very rare: longer body mite Demodex injai (greasy skin, Terriers) shorter body mite Demodex sp. (cornei) Demodex cati & Demodex gatoi of cats are extremely rare (often associated with FeLV/FIV) NB: D. gatoi is unlike all the other Demodex species, being transmissable and causing a sarcoptes like intense pruritus

35 Transmission Demodicosis is not considered a contagious disease; no horizontal transmission (except D. gatoi) Mites are only transmitted from the bitch to nursing puppies Stillborn pups from infected dams free of mites Puppies delivered by Caesarean do not have mites if not allowed contact with the dam Tendency to develop clinical disease, demodicosis, influenced by: genetic T-cell defect (hereditary) Immunosuppression due to debilitating disease Immunosuppressive medications (e.g. steroids)

36 Demodicosis Predisposing Factors As well as immunosuppression from disease or medications, other predisposing factors: Short hair Poor nutrition Stress Oestrus Endoparasites Pyoderma

37 Exclusively on host Fusiform eggs (lemon shaped) 6 legged larvae (2 stages) 8 legged nymphs (2 stages) Adults days Life Cycle

38 Clinical Signs 1 Erythema Papules Comedones Alopecia Scaling Hyperpigmentation Pruritus not usually a feature unless secondary factors

39 Clinical Signs 2 Secondary pustule formation Severe disease; follicles rupture = furunculosis with deep lesions & crusting Lesions anywhere on body; face & feet most commonly affected Generalised cases may also show depression, lethargy, lymphadenopathy

40 Human Demodicosis Canine Demodicosis

41 Diagnosis Deep skin scrapings +/- trichograms A small area of skin (1-2 cm 2 ) scraped in direction of hair growth until capillary bleeding A blade covered with liquid paraffin is used Follicular papules or pustules are good sites for scraping Squeezing skin helps push mites out of follicles

42 Demodex canis on microscopy

43 Deomodex in Skin Scrapings Demodex mites are a normal part of cutaneous fauna so occasional mites can be found normally extremely rare to see more than one Demodex canis mite in a dog not affected by demodicosis Note the site of scraping & relative numbers of adults, larvae, nymphs & eggs per field Assessment of response to therapy relies on comparison of such numbers Scrapings ideally repeated at the same sites monthly

44 Categorisation of Disease LOCALISED GENERALISED 1) Juvenile Onset 2) Adult Onset (PODODEMODICOSIS)

45 Localised Demodicosis 3 to 6 months Up to 4-6 focal lesions Mild signs, especially periocular & top of head Lesions often wax & wane Majority; spontaneous resolution in 6 to 8 weeks Good prognosis

46 Generalised Demodicosis 1 1) JUVENILE ONSET 3 to 18 months 12 or more lesions or large patches of coalesced lesions and/or paw involvement More severe dermatological presentation Systemic signs Good prognosis Up to 50% of cases in dogs <1 year old resolve spontaneously

47 Generalised Demodicosis 2 2) ADULT ONSET 4 years+ with no prior history of Demodicosis Usually follows some form of immunosuppression Neoplasia Hyperadrenocorticism (Cushings) Hypothyroidism Immunosuppressive treatments e.g. glucocorticoids, chemotherapy Atopy Often poor prognosis

48 Pododemodicosis Pedal lesions Extremely uncomfortable Difficult to treat

49 Treatment - Localised Often resolves spontaneously Miticidal therapy may not be required; however, may expedite improvement in clinical signs eg. Advocate monthly Treatment may be necessary for concurrent bacterial infections

50 Advocate Treatment - Generalised Can be used monthly; better results weekly Use weekly for 6-8 weeks, assess response based on mite counts, if improving continue weekly until resolution (often takes many months) Skin scrapes / hair plucks at least every month & continue treatment until no live mites found at two scrapes a month apart Amitraz wash sometimes used full dog clip & prolonged contact time + Additional treatments for underlying disease

51 Treatment of Demodex Expectation! it s not 100% like Sarcoptes resolution of clinical cases often takes many months understandably vets often give up much sooner Treatment aim is to control mite numbers back to a commensal level rather than cure Mild to moderate first opinion cases Licensed products good first line option Severe generalised cases often need referral & dermatologists use oral off label ivermectin

52 Additional Treatments Multi-factorial disease - advisable to also treat any underlying disease appropriately (in particular in adult onset disease) Treat accompanying skin signs, e.g. pyoderma Treat underlying systemic disease Response to any therapy may be incomplete unless predisposing factors are addressed. DO NOT USE STEROIDS

53 Advocate Examples day -1 day 112

54 Control Eliminate demodex carriers from breeding line; castrate affected males, spay affected females (NB also a chance of relapse of disease during season so beneficial to individual too)

55 Summary

56 Sarcoptes scabiei var. canis Relatively common in dogs Extremely rare in cats Intense pruritus especially ears and elbows Highly contagious & zoonotic Do not rely on blood test Responds well to treatment; 2 Advocate applications at 4 week interval Treat all in-contacts Prognosis good

57 Otodectes cynotis Very common in dogs and cats Pruritus & dark brown / black wax Contagious close contact Responds well to treatment - 2 Advocate applications at 4 week interval Treat in-contacts Prognosis good

58 Demodex canis Low numbers; normal fauna in many dogs Disease often indicates underlying disease (esp. in older dogs) Alopecia +/- pruritus Non contagious (horizontally) Spontaneous resolution in some localised cases Advocate best results weekly Generalised cases often difficult to treat over many months and prognosis may be poor

Demodectic Mange. The initial increase in number of demodectic mites in the hair follicles may be the result of a genetic disorder

Demodectic Mange. The initial increase in number of demodectic mites in the hair follicles may be the result of a genetic disorder Demodectic Mange (Demodicosis) Basics OVERVIEW An inflammatory parasitic skin disease of dogs and rarely cats, caused by a species of the mite genus, Demodex Skin disease is characterized by an increased