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Flashcards in Equine skin disease Deck (73)
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1

How are equine skin diseases categorised?

Infections or non-infectious

2

List infectious equine skin diseases

- ectoparasite (infestation)
- dermatophilosis
- folliculitis
- fungal (dermatophytosis)
- viral (aural plaques)

3

Non-infectious skin diseases

- allergies
- immune-mediated
- endocrinopathies
- miscellaneous
- neoplastic

4

What ectoparasites can affect horses?

- Chorioptes spp
- Psoroptes spp
- Neotrombicula autumnalis, Demanyssus gallinae
- RARE: scabies, demodex
- Ticks, lice, fleas, flies

5

Where are chorioptes found?

limbs and tail (pastern dermatitis)

6

Where are Psoroptes spp found?

head and ears

7

What causes equine chorioptic mange?

Chorioptes bovis, especially feathered horses

8

CS - chorioptic mange

pruritus, erythema, crusts, papules,
- peaks in WINTER

9

Tx - chorioptic mange

- challenging, often recurrent
- clipping (especially feathered)
- fipronil spray (repeat after 1 month)
- avermectins (controversial efficacy)
- permethrins/pyrethroids - flumethrin is acaricidal

10

CS - lice infestation

pruritus variable, very host specific

11

Tx - lice infestation

- fipronil spray (2tx, 10 days apart)
- synthetic pyrethroids
- systemic ivermectin

12

Dx - lice infestation

ID parasites

13

How can flies be a problem to horses?

- bites and stings
- hypersensitivity (culicoides - sweet itch)
- larvae (myasis)
- disease transmission (Habronemiasis, Ochocerchiasis)

14

What fly species can affect horses?

- Tabanus (horse fly)
- Stomoxys (stable fly)
- haematobia spp
- Muscids
- Culicoides spp
- Hyrotea spp.
- Hippobosca equina
- Simulium spp.

15

What causes itchy bottom?

Pinworm infestation (oxyuriasis): Oxyuris equi adult worms migrate from terminal parts of intestines out of anus to lay eggs --> tail rubbing, self-trauma around tail base, restlessness

16

Dx - pinworm infestatin

- handheld lens OR
- acetate tape and microscope to ID eggs

17

Tx - pinworm infestation

anthelmintics

18

What is the commonest skin allergy in horses?

sweet itch / culicoides bite hypersensitivity

19

CS - sweet itch

- seasonal pruritus
- excoriations
- alopecia
- SECONDARY LESIONS: papules, crusts, skin thickening, alopecia (primary lesions not well described)
- Dorsal or ventral midline
- restlessness and weight loss

20

2 forms of sweet itch

- dorsal distributed - commonest
- ventral biting Culicoides

21

Where is sweet itch common?

- culicoides spp regions
- wet fields, little wind
- animals > 6 months

22

Ddx - sweet itch

- Oxyuris equi
- other insects
- other allergies

23

Dx - sweet itch

- clinic
- midges
- (intradermal/ serology testing of little value since they only indicate exposure)

24

Management - sweet itch

1.) AVOIDANCE - stable 4pm-8am, rugs and hoods, fans, fly screens and traps, windy, dry grazing
2.) REPELLANTS AND LONG TERM INSECTICIDES: synthetic pyrethroids (cypermethrin, flumethrin, deltamethrin. Frequent administration essential)
3.) ANTI-INFLAMMATORIES/ANTI-PRURITIC - antihistamines and GCs (severe)

25

What bacteria infect equine skin?

- Staphylococci
- Dermatophilus congolensis
- Many others

26

How are equine bacterial skin infections diagnosed?

As in small animals - cytology (pathognomic railroad tracks seen)

27

What type of bacteria is Dermatophilus?

branching filamentous actinomycete
mainly affects ruminants and horses
varied clinical presentations

28

Describe Dermatphilus congolensis in cattle.

significant economic importance in central and west affrica - severe form in cattle infested by Amblyomma variegatum tick

29

What is Dermatophilus associated with in temperate climes?

moisture and skin trauma

30

Colloquial names - Dermatophilosis

Fleece rot - sheep
Mud fever - horses (also mud rash, greasy heal, pastern folliculitis)
Rain scald - horses