Equine Derm Flashcards
Non-infectious equine skin diseases?
- allergies
- immune mediated
- endocrinopathy
- misc
- neoplasia
Potential infectious skin diseases of horses?
- ectparasites
- dermatophilosis
- folliculitis
- fungal (dermatopyhtosis)
- viral (aural plaques)
Which ectoparasites affect horses? Esp common?
- chorioptes mite esp common (limbs and tail)
- psoroptes mite bit common (head and ears)
- neotrombicula autumnalis, Dermanyssus gallinae (seasonal)
- rarely: scabies, demodecosis
- ticks, lice, fleas, flies
Where is chorioptes often seen?
- feathered hgorses
- pastern dermatitis
- peaks in winter
Clinical signs chorioptes?
- pruritis, erythema, crusts, papules
Tx chorioptic mange?
- fipronbil spray (repeat monthly, lots needed)
- avermectins (efficacy controversial)
- permethrins/pyrethroids (flumethrin acaricidaL)
> clip feathers
Clinical signs of lice infestation?
- pruritis variable
- identify parasites!! people overlook
Tx lice infestation
- fipronil spray
- syth pyrethroids
- systemic ivermectin (H. Asini sucking lice)
are lice contagious?
Yes but species specific so only horses need treating
How may flies cause problems in horses?
- bites and stings
- infected woudns
- hypersensitivity (esp culicoides sweet itch)
- laral myasis
- disease transmission (habronemiasis and onchocerchiasis)
What worms cause itchy bottoms?
- pinworms
- oxyuris equi
> adults migrate from LI out of anus to lay eggs - self trauma
Most common skin allergy in horses?
Sweet itch
- insect bite hypersensitivity
Where is sweet itch seen? WHen?
USually dorsal but ventral fly also exists
- always seasonal! Not winter
Clinical signs of sweet itch??
- papules, crusts, skin thickening, alopecia
- seasonal pruritis
What aged hroses sweet itch affect?
- > 6 months
Ddx sweet itch?
- oxyuris equi
- insects
- other allergies
Is intradermal testing for sweet itch indicated?
- shows exposure not hypersensitivity
Does ASIT work for sweet itch?
No!!
Tx sweet itch?
- anti-inflammatories/antipruritic (antihistamines, GCs)
- management
> flies live in areas of wet fields and low winds and cannot fly far
> move horses!
> rungs/hoods/fly spray
> stable between 4pm and 8am
> long term insecticides and repellants (synth pyrethroids [cypermethrin, flumethrin, deltamethrin, CARE FLISH!]
Most common bacterial disease on the horse? How are these diagnosed? `
- Dermatophylsis congolensis (actinomyces) mud fever, affects cattle too if rain heavy > cytology on whole crust mixed with saline: “railroad tracks” may branch (not bacterial culture!)
- Staph aureus/pseudintermedius (NB. superficial pyoderma can be painful) > cytology
- rarely strep infections
Which horses are predisposed to med fever?
White limbs
When do cattle get rain salad/mud fever?
Serious tick infestation (Africa severe form)
- allows opportunistic Dermatophylsis congolensis
What does Dermatophylsis congolensis cause I’m other species ?
Rain scald
Sheep wool something
Cattle
What is mud ever also known as?
Mud rash
Greasy heel
Pastern folliculitis
Management and treatment of mud fever?
Look up papers
Management and husbandry changes
- chorioptes/ringworm/other pahtogens in mixed infection eradicated
What are aural plaques?
- papillomavirus infection
- hyperkeratotic plaques
- concave aspect pinnae
- common esp. yearlings and older
- Simulan spp. (midges) = vectors
- often persist but do not bother horse!!
- therapy = observation, do not tx unless causing problems!
Why is dermatophytosis treatement always indicated?
Zoonotic and contagious
Which species cause ringworm in horses?
- trichopyton
- m equinum and m gypseum
Pathogenesis of ringworm?
Resolvves in healthy horse within 5-6 weeks
CLinical signs dermatophytosis?
- may be pruritic
- same principles as SA (hair pluck/brush submit for fungal culture)
Tx ringworm?
> NOTHING LIC IN HORSES > offlicense: - topical griseofulvin/potassium iodide - malaseb - isolation and hygeine
Vax for dermatophytosis in the hrose?
No
What is a comon signs of horse with allergy?
- urticaria +- pruritis
> culicoides/food/atopic/{contact dermatitis?}
Potential immune mediated/autoimmune skin disease in horse?
- pemphigous foliacious (often accompanied by swelling and oedema)
- erythema multiforme [reaction pattern, not Dx] (may look = urticaria but urticaria will pit on pressure, erythema will not pit)
- adverse drug reactions
- vasculitis [reaction pattern, not Dx] (purpura haemorrhagica)
- alopecia areata (immune attack hair roots)
> reaction patterns may indicate neoplasia, infection etc.
What is PPID?
- cushings
- pituitary pars intermedia dysfunction
- hyperplasia of pituitary pars intermedia
clinical signs of PPID?
- old horses/ponies
- PUPD
- lethargy
- poor thriving
- 2* infections ^?
- hirsuitism
- laminitis
> MORE SEE SLIDE
What are systemic granulomatous diseases?
- or chronic eosinophilic enteritis (may be same thing or slightly different diseases?)
- also known as equine sarcoidosis (NOT RELATED TO SARCOIDS)
- wasting disease
- skin and GI affected
- aetiology unknown (hairy vetch? mycobacterium? viral antigen?)
- grave prognosis
Tx systemic granulomatous diseaase? Prognosis?
- change feed
- systemic GC months
- spontaneous recovery?
> prog grave
Clinical sings and dx of systemic granulomatos disease?
- exfoliative dermatitis (scaling)
- crusting
SEE SLIDE ADD MORE
How sudden onst is systemic granulomatous disease?
Acute onset v sudden onset
How id dx systemic granuloatous?
- liver function tests
- histopath
WHat 3 factors needed for photosensitisation? What 2 forms exist?
1* ( st. johns wort, phenothiazine)
2* (phylloerythrin due to liver disease)
> UV + poorly pigmented skin+ photodynamic agent in skin all needed
What photo induced disease are white limbs susceptable to?
- leucocytoclastic vasculitis
> acute onset erythema, oozing, crusting
> v painful
Dx. leucocytoclastic vasculitis?
- biopsy
sedate first!!
3 possible groups of nodular skin issues?
- sterile (often harmless, little known about them)
- collagenolytic granuloma
- cutaneous mastocytosis
- axillary nodular necrosis
- unilateral papillomatosis - infectious(microbial/parasitic - can be tx)
- botryomycosis
- habronemiasis
- dermatophilosis
- dermatophytosis - neoplastic
- malignant
- benign
What is eosinophilic granuloma also known as?
- eosinophilic grnauloma
- nodular necrobiosis
- SEE SLIDE
CLinical signs eosinophilic granuloma?
see slide
Dx collagenolytic granuloma?
- history (not v speciffic) > afge, speed of onset, seasonality, tx, systemic disease - tests > fungal/bacterial culture > FNA cytology > histopath for definitive dx
Ddx collagenolytic granuloma?
See slide
Is collagenolytic grnauloma harmful to horse?
No
Tx collagenolytic granuloma
- leave alone
- surgical excission if few
- GCs (systemic, intralesional, sublesional)
Prognosis collagenolytic granuloma?
see slife
See slide for sarcoid types Ddx
Which other species may get sarcoids?
- felines (esp. farm cats, zoo cats too)
