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Infectious equineskin problems

Marianne M. Sloet van Oldruitenborgh-Oosterbaan

Departement of Equine Sciences

Faculty of Veterinary Medicine

Utrecht University

the Netherlands

Infectious skin diseases

� viral

� bacterial

� fungal

� parasites

papillomas = warts

aural plaques

=

equine earpapillomas

Molluscum contagiosum

� molluscipox virus

� well demarcatedhyperplasia

� keratinocyten are called‘molluscum bodies’

Sarcoids

� occult sarcoid

� verrucous sarcoid

� nodular sarcoid

� fibroblastic sarcoid

� mixed sarcoid

� malevolant sarcoid

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16 year oldTrakener gelding

Sarcoids are the most common skin tumour

Sarcoid therapy

� surgical excision

� cryochirurgy

� local immune therapy with BCG

� laser therapy

� Knottenbelt - ointment

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Infectious skin diseases

� viral

� bacterial

� fungal

� parasites

dermatophilosis

botryomycosis

=

bacterialpseudomycetoma

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GlandersCourtesy Lidwien Verdegaal

Skin problems lower limbs

� pastern dermatitis

� folliculitis

� Einschuzz (cellulitis/vasculitis)

� ulcerative lymphangitis

� leucocytoclastic pastern dermatitis

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Infectious skin diseases

� viral

� bacterial

� fungal

� parasites

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Fungal infections in horses

� Trichophyton equinum

� Trichophyton mentagrophytes

� Trichophyton verrucosum

� Microsporum canis

� Microsporum equinum

� Microsporum gypseum

InsolInsol®® DermatophytonDermatophyton where to vaccinate?where to vaccinate?

� deep intra-muscular

� muscle is preferably ‘relaxed’

� thigh is preferred

� pectoral muscle is also suitable

� preferably not in the neck

� alternate sides between vaccinations

� 139 dierenartsen

� 2486 paarden

4 weeks after 2nd vaccination(-)

5%(+)

7%

(++)

26%(+++)

62%

When to vaccinate with When to vaccinate with

InsolInsol®®DermatophytonDermatophyton? ?

� horses with clinical signs of dermatophytosis

� possible infected horses

� horses due to travel

(second injection has to be administered at least 14 days prior to departure)

� all horses on premises with historically problems

hygiene is essential !!!

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Remember ……when a horse has dermatophytosis,but does not show clinical signs (yet), these symptoms will show soon

after vaccination !

When not to vaccinate with InsolWhen not to vaccinate with Insol®® D ? D ?

� reduced immunity

- foals younger than 5 months

- sick or stressed horses

� pregnant mares ??

� close before important events!

hygiene is essential !!!

Sporothrix schenkii

Infectious skin diseases

� viral

� bacterial

� fungal

� parasites

Importance of dermatoses caused by ectoparasites?

Utrecht University

1. Insect bite hypersensitivity2. Chorioptes3. Pediculosis4. Dermanyssus gallinae

Ectoparasites I

� Arachnids – Acarina

- Astigmata (Sarcoptes, Psoroptes, Chorioptes)

- Prostigmata (Thrombiculidae + Demodex)

- Mesostigmata (Dermanyssus)

- Metastigmata (Ixodus, Dermacentor)

� Insecta – Exopterygota

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Ectoparasites II

� Insecta - Exopterygota

- Mallophaga (Werneckiella)

- Siphunculata (Haematopinus)

- Diptera (Culicoides, Gasterophilus, Hypoderma, Hippobosca)

� Nematoda

Ectoparasites III

� Nematoda

- Ascaridida (Oxyuris)

- Spirurida (Habronema, Draschia,

Parafilaria, Onchocerca)

Acarina

� Sarcoptes

� Psoroptes

� Chorioptes

� Thrombiculidae

� Demodex

� Dermanyssus

� Ixodus / Dermacentor

Sarcoptes, Psoroptes, Chorioptes

� mostly late winter – early spring

� contributing factors

- crowding

- prolonged stabling

- suboptimal nutrition

- environmental temperature

� limited host specificity

Sarcoptes

� 0.25-0.6 mm in diameter

� tunnel through epidermis

� feed on tissue fluids + epidermal cells

� life cycle on host ± 2-3 weeks

� off-host survival time only a few days

� ‘endangered species’

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Sarcoptes

� starts on the head

� very severe pruritus

� anaemia may occur

� secondary infections may occur

� mites very difficult to find

� often ‘diagnostic therapy’

Sarcoptes

� treatment with appropriate spray or dip

at least two times - 10-14 days between

� few or even no products licensed

� in the Netherlands we use foxim – Sebacil®

� ivermectine should be useful

� reportable disease in many countries

Psoroptes

� 0.4-0.8 mm long

� nonburrowing

� feed on tissue fluids

� life cycle on host ± 10 days

� 14-18 days off-host survival time

but incidentally up to 84 days?

Psoroptes

� P. equi, P cuniculi, P. natalensis and P. ovis are found on horses

� we did not diagnose it for > 25 years

� pruritic dermatitis of trunc and/orear disease with head shaking

� mane and tail seborrhoea

� mites rarely found

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Psoroptes

� ivermectine is very effective in the treatment of psoroptesotoacariasis and/or dermatitis

� eggs are not killed – second dose after 14 days necessary

� efficacy of ivermectine may be explanation for ‘extinction’

� often unnecessary treatment in the ears??

Courtesy Derek Knottenbelt

Chorioptes

� 0.3-0.5 mm long

� surface-inhabiting mites

� feed on normal debris

� life cycle takes ± 3 weeks on host

� survival off host 70 days

� C. bovis, C. caprae, C. equi, C. ovis

Chorioptes

� starts on the lower limbs

� often horses with feathered fetlocks

� more during winter

� pruritus varies from absent to intense

� widespread lesions may occur

� mites easy to find

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therapy ??

Ectoparasite therapy

� systemic treatment – ivermectine ??doramectine ??

� topical treatment

- first clip feathers

- bath the horse (10 min contact time)

- repeat 5-10 days intervals

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Thrombicula larvaCourtesy Derek Knottenbelt

Thrombiculidiasis

� thrombiculid larvae ± 0.2-0.4 mm long

� thrombiculid adults and nymphes are free-living

� larvae normally feed on tissue fluids of small rodents, but incidentally horses

� generally in late summer and fall

� entire life-cycle 50-70 days (7-10 days feeding as larvae on host)

Thrombiculidiasis

� infestation primarily in pastured horses

� papules and wheals

� muzzle, face, distal limbs

� to make the diagnosis: chigger larva seen in the centre of the lesion

� variable pruritus

� often self-limiting / topical treatmentThrombiculidiasis

Courtesy Derek Knottenbelt

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Demodex

Demodex

� ± 0.2 mm long (D.caballi + D. equi)

� normal residents of the skin in the hair follicles and sebaceous glands

� feed on normal debris

� life cycle takes ± 20-35 days on the host

� survival off host few hours to days

� probably not a contagious disease

Demodex

� only clinical after long-term glucocorticoid treatment

� most times asymptomatic

� alopecia and scaling, over the face, neck, shoulders and forelimbs

� papules and pustules may be seen

� deep skin scrapings necessary

� treatment not attempted

Dermanyssus gallinae – poultry miteDermanyssus gallinae

� ± 0.6-1.0 mm long

� incidentally on horses

� pruritic papules and crusts in contact areas

� horse can be sprayed or dipped

� eradication of the mite from the premises (and the poultry)

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Thicks may harm!

� injuries done by bites

� sucking blood

� transmitting various diseases

- Borrelia burgdorferi- Anaplasma phagocytophilum- Babesia caballi- Theileria equi

� causing thick paralysis

Thicks

� Ixodus ricinus, Dermacentor reticulatus

� incidentally in spring and summer

� may attack any part of the body surface

� papels, pustules, wheals

� later crusts, erosions, ulcers, alopecia

� pain and pruritus are variable

� anaemia

Thicks

� use of suitable insecticides

� knowledge of local insecticidal resistance

� in the Netherlands – fipronil / permethrin

Insects

� Werneckiella

� Haematopinus

� Culicoides

� Gasterophilus

� Hypoderma

� Hypobosca

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Lice infestation

� biting lice = Werneckiella equi = Damalinia equi

� sucking lice = Haematopinus asini

Werneckiella equi

� 3-6 mm in lenght (nits 1-2 mm)

� ‘moving dust’

� more in winter months

� feeds on cutaneous debris

� prefers dorsal trunk

� pruritus mild to moderate

� varying degrees of scaling and alopecia

Haematopinus asini

� 3-6 mm in lenght (nits 1-2 mm)

� very rare in our area

� feeds on blood and tissue fluid

� favor main, tail and fetlocks

� may cause anaemia

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Culicoides spp.

Gastrophiliasis – bots

� Gasterophilus intestinalis = G. equi

� G. nasalis, G. haemorrhoidalis, G. pecorum, G. inermis

� active in summer

� adult females glue eggs to hairs on legs and shoulders

� cutaneous gastrophiliasis – 1-2 mm wide greyish-white crooked streaks

Courtesy Derek Knottenbelt

Gastrophiliasis – therapy

� self-limiting

� rarely symptomatic

� treatment of gastric larvae in November –December

� ivermectin / moxidectin

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Hypodermiasis– ox warbles

� Hypoderma bovis and H. lineatum

� close contact to cattle

� egg – larvae – skin penetration –subcutaneous tissue

� H. bovis – spinal canal and epidural fat

� H. lineatum – submucosal connective tissue of the oesophagus

� second stage larvae to dorsum

� swellings of the back with breathing pore

http://www.fao.org/docrep/003/t0756e/T0756E109.jpg

Hypoderma – therapy

� confirm diagnosis !!

� enlarging breathing pore and extracting the larva

� surgical excision of the whole nodule

� wait and allow larvae to drop out by themselves

� prevention: deworming with ivermectinor moxidectin

Differential diagnosis

???

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Hippoboscus equina – louse fly

Hippobosca equina – louse fly

� adult louse suck blood

� tender to cluster in the perinealand inguinal regions

� only in import horses

� horses may be ‘irritated’

� therapy: insecticide

Lucilia sericata – myiasis

� adult blowflies lay clusters of light-yellow eggs in wounds

� larvae hatch within 8-72 hours

� larvae reach full size in 2-19 days

� treatment

- cleansing and debriding

- topical insecticide

- symptomatic therapy

Helminths

� Oxyuris

� Habronema / Draschia

� Parafilaria

� Onchocerca

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Oxyuris and Habronema adultsCourtesy Derek Knottenbelt

Oxyuriasis – pin worms

� Oxyuris equi , Probstmayria vivipara

� lives in coecum and colon

� adult females lay eggs around anus

� variable pruritus

� incidentally restless and irritable

� acetate tape – diagnosis

� therapy: routine worming

Oxyuris

Oxyuris eggCourtesy Han van der Kolk and Debora van Doorn

Habronemiasis

� summer sores

� swamp cancer

� granular dermatitis

� begins in spring and summer

� regresses partially or completely in winter

Habronemiasis

� H. muscae, H. majus + Draschia megastoma

� adults inhabit the stomach

� eggs and larvae passed with faeces

� Musca domestica + Stomoxys calcitrans

� infectious larvae deposited on the horse in moist areas or open wounds

� larvae near mounth are swallowed –complete parasitic life-cycle

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Habronema /

Draschia spp.

Courtesy Derek Knottenbelt

Habronema / Draschia spp.Courtesy Derek Knottenbelt

Habronemiasis

� perhaps partly a hypersensitivity disorder

- sporadic (one animal in a herd)

- seasonal

- recurs in same horse every summer

- systemic corticosteroids may be curative

� no optimal therapeutic protocol

(surgery, local and systemic therapy)Habronema / Draschia spp.

Courtesy Derek Knottenbelt

Habronema / Draschia spp.Courtesy Lidwien Verdegaal

Habronema / Draschia spp.Courtesy Lidwien Verdegaal

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Parafilaria multipapilosa

Parafilaria multipapillosa

� parafilariasis

� haemorrhagic filariasis

� summer bleeding

� only import horses in the Netherlands

� adult worms (3-7 cm) live in the connective tissues coiled within nodules

� nodules open at the surface and discharge a blood exsudate (eggs, larvae)

� therapy: time + avermectines?

Onchocerciasis

Onchocerca cervicalis

Onchoceriasis

� O. cervicalis, O. reticulata, O. gutturosa

� adult worms live in lichamentum nuchaeor in connective tissues of tendons

� microfilaria numerous in ventral midline

� Culicoides spp. are intermediate host

� in the Netherlands not diagnosed for over 25 years

Onchocerca Courtesy Derek Knottenbelt

Halicephalobiasis

� Halicephalobus gingivalis = Halicephalobus deletrix = Micronemadeletrix = Rhabditis gingivalis

� details of life cycle not known

� multiple organ systems can be infected

� cutaneous lesions uncommon

� diagnosis confirmed by biopsy

� treatment ??