Horse Dermatology

Question 1

Predilection site for Chorioptes.

How to identifty Chorioptes

Answer 1

Limbs and tails.

Chorioptes have long legs as are surface mites

Question 2

Horse fly genus

Answer 2

Tabanus.

Stomoxys = Stable fly

Question 3

Treatment for Lice infection in horses

Answer 3

Fibronil spray. Can normally see lice with naked eye

Question 4

Tail rubbing and self trauma around the tail base would make you suspitious of…

Answer 4

Pinworm infestation (Oxyuriasis) 
Adult worms migrate from terminal parts of large intestines out of anus to lay eggs.

Question 5

The equivalent of FAD in horses is known as

Answer 5

Sweet itch (Culicodies). Most common skin allergy in horses. 
Seasonal pruitis, papules, crusts and skin thickening. Dorsal or vertral midline.

Question 6

Management changes to help reduce sweet itch

Answer 6

Always check Pin worm status.
Stable between 4 and 8am. Rugs/hoods/ windy dry fields.
Repellents and Longterm insecticides (Pyrethoids)

Question 7

‘Rail track’ on DiffQuick cytology of horse leg lesion (exudate, matted hair) is indicative of

Answer 7

Dermatophilosis conglenisis. Dorsum or limbs (mud fever)

Question 8

Aural plaque pathogenesis and treatment

Answer 8

Hyperkeratoic plaques on concave aspect of ear. Common.
Simulium vectors.
DON’T TREAT; INCIDENTAL

Question 9

Treatment of Dermatophytosis in horses

Answer 9

Healthy host; spontaneous resolution within 5-6 weeks. Pruitic in horse. Fungal culture for diagnosis as yard outbreak needs to be confirmed before.

Question 10

Pathogenesis of Alopecia areata.

What is the main Ddx

Answer 10

Immune attack on hair bulb needs. Diagnosis by biopsy.

Main Ddx is Dermatophytosis

Question 11

Main skin change in PPID in horses

Answer 11

Hirsuitism (long hair)
Hyperhyrsosis,
Laminitis.
Hyperplasia of the pituitrary pars intermedia

Question 12

In a horse with poorly pigmented skin, work up of the skin disease should include

Answer 12

Liver enzymes as Phyllerythrin due to liver disease = secondary ph.

Question 13

Pathogenesis of Systemic granulomatous disease and Chronic eosinophilic enteritis

Answer 13

Oxfolative dermatitis= generalised scaling, often crusting, alopecia or nodules.
Systemic signs: Severe wasting, fever, icterus, diarrhoea.

Question 14

An acute onset erythema, oozing, crusting and painful in non-pigmented lower limbs could be…

Answer 14

Leucocytoclastic vasculitis. Need to confirm diag via biopsy before starting immunosuppressive therapy.
Liver enzymes should be checked as only white area affected (rule out Liver disease)

Question 15

How to differentiate Nodular disease from Urticarial disease

Answer 15

Apply pressure, urticarial disease will pit with pressure.

Question 16

Collagenolytic granuloma

Answer 16

Cause unknown possibly hypersensitivity to insect bites. Often in saddle area, neck and flanks, Mostly spring and summer.
NOT ALOPCECIA, ULCERTATIVE OR PAINFUIL.
Chronic lesions lead to Mineralisation

Question 17

Ddx from Collagenolytic granuloma

Answer 17

Papular dermatitis, Staphylococcal folliculitis & furunculosis, dermatophytosis, neoplasia, cutaneous amyloisosis

Question 18

Equine sarcoids restricted to which layers

Answer 18

Skin and Subcutis. Common at fly predilection sites and wounds.

Question 19

Six clinical sarcoid entities. Considerations of biopsy

Answer 19

1. Occult
2. Nodular
3. Verrucous
4. Fibroblastic
5. Mixed
6. malevolent
   CAN PROGRESS FROM ONE FORM TO ANOTHER WHEN TRAUMATISED THEREFORE CARE WITH BIOPSY

Question 20

Occult sarcoid

Main Ddx

Answer 20

Flat, eyes mouth hairless areas. Main Ddx: Dermatophytosis, burns, trauma

Question 21

Nodular sarcoid

Main Ddx

Answer 21

Groin, sheath, eye lid, subcut nodules.

Main Ddx: Fibroma, Melanoma, Collagenolytic, Granuloma, Warble Fly cysts

Question 22

Verrucous sarcoid

Main Ddx

Answer 22

‘Warty’ Face&Body nodules, thickening.

Main Ddx@ Papillomatosis, Chronic sweet itch, SCC

Question 23

Fibroblastic sarcoid

Answer 23

Groin, eyelids. limbs. wounds fleshy/ulcerated.

Ddx: Granulation tissue,

Question 24

Why does care have to be taken when biopsy is taken off suspected equine sarcoid

Answer 24

Diagnostic but may encourage progression. Excisional better than partial. Contradinidicated if lesions static over a long time

Question 25

Surgical removal of equine sarcoids is best reserved for…

Answer 25

Nodular, occult (flat) and verrucous ‘warty’ sarcoids only.

Question 26

Why are farm cats more predisposed to getting Feline Sarcoids?

Answer 26

As sarcoids are thought to be transmitted by flies / Bovine papillomavirus

Question 27

What is the required test for a horse with suspected SLE?

Answer 27

Systemic lupus erythematosus = lupus. ANA test
Cutaneous signs utaneous signs predominate:
Exudative polyfocal or diffuse/generalized hyperkeratosis/exudation.
Scaling and flaking.
Crusting if exudative.

Question 28

Clinical signs of SLE in horse

Answer 28

Systemic lupus erythematous. Multi-systemic autoimmune disease. Signs vary from mild limb oedema to multiple organ failure.. Treatment corticosteroids. Poor prog
Cutaneous changes predominant: utaneous signs predominate:
Exudative polyfocal or diffuse/generalized hyperkeratosis/exudation.
Scaling and flaking.
Crusting if exudative..

Question 29

Relevance of acanthocytes in a horse with lethargy, wt loss, papules and scaling? `

Answer 29

Acanthocytes= rounded off epithelial cells which are highly suggestive of Pemphigus foliaceus

Question 30

Clinical features of Mud Fever

Answer 30

Mud Fever in horses= Dermatophillosis. Exudate, matted hair, alopecia.
Main Ddx is Staph

Question 31

Demidocosis in horses

Answer 31

Ivermectin.

Amitraz is CONTRAINDICATED IN HORSES (Effect on gut motility)