Dermatology (Excluding The Bits Poppy Covered) Flashcards
Top differential for lesions of the mane, tail and ventral line
Insect bite hypersensitivity
Top differential for tail rubbing/hair looks on tail
Oxyuris equi
Insect bite hypersensitivity
Lice infestation
Common conditions presenting as macule/patches (circumscribed flat impalpable colour change areas)
Alopecia areata
Vitiligo
Common conditions presenting as papules and plaques (solid circumscribed discoloured firm areas)
Bacterial infection
Fungal infections
Some ectoparasites
Common conditions presenting as vesicles (raised fluid-filled well demarcated lesions)
EHV-3
Vesicular stomatitis
Pemphigus foliaceus
Common conditions presenting as Pustules
Bacterial infections
Insect bites
Fungal infections
Common conditions presenting as wheals (flat topped, oedematous raise lumps with no skin changes)
Urticaria
Food allergies
Insect stings
Common conditions presenting as nodules (raised circumscribed solid lumps extending deep into dermis)
Papilloma
Sarcoid
Melanoma
Eosinophilic granuloma
Exuberant granulation tissue
Common conditions presenting as neoplasia
Melanoma
Sarcoids
Cutaneous lymphoma
Fibromas
Mastocytoma
Histiocytoma
Common conditions presenting as abscesses
Trauma
Streptococcal, clostridial (c, pseudotuberculosis) infection
Common conditions presenting as alopecia
Self mutilation from pruritis
Healing fungal-bacterial infections
Common conditions presenting as scale
Ectoparasites
Pemphigus
Chronic fungal-bacterial infections
Common conditions presenting as crusts
Chronic fungal-bacterial infections
Pemphigus
Chronic mites
Systemic lupus
Common conditions presenting as erosions
Insect bite hypersensitivity
Drug reaction 2nd to scratching
Common conditions presenting as ulcers
Pressure sores
Habronemiasis
Common conditions presenting as lichenification
Sarcoidosis
Pemphigus
Systemic lupus
Common conditions presenting as hyper/hypopigmentation
Repeated trauma
Healing fungal-bacterial infections
What can swollen frayed hair shafts indicate
Dermatophytosis
What test should you send for if suspect of dermatophytosis
PCR as faster than culture
What bacteria causes rainscald
dermatophilus congolensis
What do you have to be careful of diagnosing rainscald
dermatophilus congolensis looks like fungi as shows a railroad pattern on cytology
Importance of allergy tests
Don’t currently work
Location of lesions for chorioptes equi
Distal limb +++
Groin/abdomen possible
Presentation of chorioptes equi
Signalment
-draft breeds
- feathers
- winter
Clinical signs
- rubbing/scratching/stomping distal limbs
-exudate, scabbing, alopecia
Lesion position of trombicula autumnalis
Head and leg++
Presentation of trombicula autumnalis
Densely feathered but all horses
Biting/stomping at legs
Small papules on pastern/nose
Lesion site if psoroptes equi
Head, tail, ears
Presentation of psoroptes equi
All horses
Tail rubbing/broken hairs
Scaling of ears
Ear discharge
Dermanyssus gallinae lesions
Legs face and abdomen papules/crust
Presentation of Dermanyssus gallinae
All horses
Small orange/red mite
Biting/stomping legs
Lesions of papules/crusts
Management/ treatment for chorioptes equi
Clip feathers (burn the hair)
Extensive disinfection (should allow stables to rest)
Treat all horses
Treat with Doramectin injection
- 0.25% fipronil spray daily for a week then weekly for 4
- 5% lime sulphur solution weekly for a month
Management/treatment of trombicula autumnalis
Remove straw
Avoid infected grass/woods
Treat with lime sulphur solution, pyrethrin spray or 0.25% fipronil spray
Management/treatment for psoroptes equi
Remove all organic debris from stable disinfect and rest (70 days) disinfect tack also.
Treatment
- otitis - oral macrocytic lactones
- lime sulphur solution
-Pyrethrin spray
Management/treatment of lice
Disinfect stable with 10% bleach. Wash rugs/nummahs at 60 degrees
Poss treat in contacts
Treatment
- permethrin pour on
- 0.25% fipronil spray
- 1% Se sulphide shampoo q10days X3
When is oxyuris equi common
Young horses never treated with ivermectin
When does insect bite hypersensitivity develop
3-4 years
What breeds are predisposed to insect bite hypersensitivity
Icelandic, German shires, welshies, Shetlands, Connemaras
Management for insect bite hypersensitivity
Inside at dusk till dawn - cover windows with fly mesh
Fly sheets on when out of stables
Keep away from water
Fly repellent
How does food allergy present in the horse
Type 1 hypersensitivity
Face neck and trunk lesions
Angioedema and urticaria
How does contact dermatitis present in the horse
Type 4 hypersensitivity
Erythema, oedema, oozing to alopecia/lichenification from tack
Mouth/ventral abdomen from tack
Management/treatment of rainscald
Wear gloves - can be zoonotic
Most spontaneously regress
Wash tack rugs etc @60 in captain
Avoid sunlight
Keep dry
antiseptic washes of lesions but dry after daily k-permanganate for 5 days
Systemic antibiotics if necessary
Predisposition for rainscald
Poor nutrition
Poor hygiene (sweat)
High temperature
High humidity
Low immunity
Causal agents of dermatophytosis
Trichophyton equinum
Mycrosporum gypseum
Management/treatment of dermatophytosis
Gloves!
Isolate and disinfect
K-monopersulphate to fog premises outbreaks
Chlorhexidine spray daily x7 days
Chlorhexidine and miconazole spray/shampoo 2-3x weekly
Most common cause of photosensitisation
Type 3 hypersensitivity caused by liver failure
What is photosensitisation
Abnormal reaction of the skin when exposed to UV radiation
What is pemphigus
Exfoliative dermatitis due to type 2 hypersensitivity with antibodies directed at dermal cells.
Poorly understood
Diagnosis of pemphigus
Acantholysis on biopsy
Treatment of pemphigus
Long term immunosuppressive glucocorticoids
Omega fatty acids
Vitamin E
Sunlight restriction
What is onchocerca
A microfilaria parasite
Treatment of onchocerca
Macrocytic lactones
How does EHV-3 present
Lesions on the vulva, perineum, penis, prepuce and testicles
Oral and lip ulcers
Venereal transmission
How do you diagnose alopecia areata
Biopsy
What is vitiligo
Idiopathic depigmentation common around eyes/lips of grey horses which Andalusians/Arabs more predisposed
What is urticaria
Immunologic reaction to allergens
Management of urticaria
Identify trigger
Wash skin if a contact reaction
Steroids
Cetirizine
Omega fatty acids
Where does pedal/pastern dermatitis affect
Caudal aspect of the pasterns
What are the primary pathogens involved in pastern/pedal dermatitis
Staphylococcus aureus and dermatophilus congolensis
What is chronic proliferative lymphedema
Elastin dysfunction in lymphatic vessels
Predisposition in shire/Clydesdale/Belgian draft
Diagnosis and management of pastern/pedal dermatitis
Clip hair and take samples
Clean and dry thoroughly
Avoid bandaging
Treat primary problem
Will be a long term issue
Causes of melanomas
Gene mutation in STX17g, changes in melanocyte behavior
Disturbance in melanin transfer
Types of melanoma
Melanocytic nevi (single/multiple discrete nodules)
Dermal melanoma (originate in deep dermis - single/multiple nodules)
Dermal melanomatosis (confluent large melanomas - risk of mets)
Malignant (rare, invasive, likely to reoccur)
Most common melanoma location
Under tail
Diagnosis of melanoma
Visual
Ultrasound
FNA
Sarcoid features
Benign
Non metastatic
Locally aggressive
Types of sarcoid
Occult
Verrucose
Nodular
Fibroblastic
Mixed
Malignant
Occult sarcoid
Hairless skin
Mild/stable/superficial
Milks hyperkeratosis
Verrucose
Rarely aggressive unless injured
Warty looking
Hyperkeratosis with flake/scale
Nodular sarcoids
Not an issue till injured
0.5-20cm
Firm, spherical subcut nodules
2 types
Confined to subcutaneous
Involvement of overlying skin
Fibroblastic sarcoids
Ulcerated, fleshy, look aggressive
2 types
Pedunculated with small base palpable under skin
Wide base diffuse/I’ll defined margins
Mixed sarcoids
Mixture of types
Malignant sarcoid
Highly invasive, infiltrative of lymphatic vessels
Repeated injury if skin lesion can result
Treatment of sarcoids
Topical creams
Banding (thin peduncle)
Intralesional chemo (cisplatin)
Laser surgery
Electrochemotherapy
Vaccines
Radiotherapy
Cause of sarcoids
Bovine papilloma virus in tissue
Potentially fly transmission
Skin trauma giving direct access to BPV to subepidermal fibroblasts leading to abnormal proliferation
Squamous cell carcinoma
Locally invasive - more common in areas with limited hair, mucocutaneous junctions and poorly haired areas
Flies, smegma and UV predisposed
Melanoma treatment
Vaccination
Intralesional therapy