Flashcards in Equine skin disease Deck (73)
How are equine skin diseases categorised?
Infections or non-infectious
List infectious equine skin diseases
- ectoparasite (infestation)
- fungal (dermatophytosis)
- viral (aural plaques)
Non-infectious skin diseases
What ectoparasites can affect horses?
- Chorioptes spp
- Psoroptes spp
- Neotrombicula autumnalis, Demanyssus gallinae
- RARE: scabies, demodex
- Ticks, lice, fleas, flies
Where are chorioptes found?
limbs and tail (pastern dermatitis)
Where are Psoroptes spp found?
head and ears
What causes equine chorioptic mange?
Chorioptes bovis, especially feathered horses
CS - chorioptic mange
pruritus, erythema, crusts, papules,
- peaks in WINTER
Tx - chorioptic mange
- challenging, often recurrent
- clipping (especially feathered)
- fipronil spray (repeat after 1 month)
- avermectins (controversial efficacy)
- permethrins/pyrethroids - flumethrin is acaricidal
CS - lice infestation
pruritus variable, very host specific
Tx - lice infestation
- fipronil spray (2tx, 10 days apart)
- synthetic pyrethroids
- systemic ivermectin
Dx - lice infestation
How can flies be a problem to horses?
- bites and stings
- hypersensitivity (culicoides - sweet itch)
- larvae (myasis)
- disease transmission (Habronemiasis, Ochocerchiasis)
What fly species can affect horses?
- Tabanus (horse fly)
- Stomoxys (stable fly)
- haematobia spp
- Culicoides spp
- Hyrotea spp.
- Hippobosca equina
- Simulium spp.
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
Dx - pinworm infestatin
- handheld lens OR
- acetate tape and microscope to ID eggs
Tx - pinworm infestation
What is the commonest skin allergy in horses?
sweet itch / culicoides bite hypersensitivity
CS - sweet itch
- seasonal pruritus
- SECONDARY LESIONS: papules, crusts, skin thickening, alopecia (primary lesions not well described)
- Dorsal or ventral midline
- restlessness and weight loss
2 forms of sweet itch
- dorsal distributed - commonest
- ventral biting Culicoides
Where is sweet itch common?
- culicoides spp regions
- wet fields, little wind
- animals > 6 months
Ddx - sweet itch
- Oxyuris equi
- other insects
- other allergies
Dx - sweet itch
- (intradermal/ serology testing of little value since they only indicate exposure)
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)
What bacteria infect equine skin?
- Dermatophilus congolensis
- Many others
How are equine bacterial skin infections diagnosed?
As in small animals - cytology (pathognomic railroad tracks seen)
What type of bacteria is Dermatophilus?
branching filamentous actinomycete
mainly affects ruminants and horses
varied clinical presentations
Describe Dermatphilus congolensis in cattle.
significant economic importance in central and west affrica - severe form in cattle infested by Amblyomma variegatum tick
What is Dermatophilus associated with in temperate climes?
moisture and skin trauma