Crusting and exudation in a Welsh stallion pony Author: Mark CraigEditor: David Lloyd © European Society of Veterinary Dermatology

Crusting and exudation in a Welsh stallion pony

Author: Mark Craig Author: Mark Craig Editor: David LloydEditor: David Lloyd

© European Society of Veterinary Dermatology © European Society of Veterinary Dermatology

History | Signs | Differentials | Tests | Therapy | NotesHistory | Signs | Differentials | Tests | Therapy | Notes

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History -1

HistoryHistory

• 10-year-old Welsh pony stallion

• Weight 300 kg


History -2

HistoryHistory

• First signs developing over a 4-week period• Papules on flank and neck, pruritus• Generalised crusting and exudation• Swelling of all four legs accompanied by stiffness and

lameness• Weight loss and lethargy

• No treatment by the referring vet


Clinical signs - 1

SignsSigns

The horse was thin and there was generalised crusting with diffuse alopecia

No peripheral lymphadenopathy was detected


Clinical signs - 2

SignsSigns

Close-up views of alopecic and crusted areas

Clipped area on the withers


How would youapproach this case?

SignsSigns

• What are the next steps you would take?

• Make a list of your principle differential diagnoses

• List any samples you would collect

• List any tests you would perform to assist in making a definitive diagnosis


Test - 1

DifferentialsDifferentials

• Principle differential diagnoses• Bacterial folliculitis, dermatophilosis,

dermatophytosis • Ectoparasitic infestation• Pemphigus complex, SLE, drug eruption• Allergy


Tests - 2

TestsTests

• Tests• Blood tests: routine haematology and biochemical

screens; ANA test• Multiple punch and excision biopsy samples from

crusted and alopecic areas• Skin scrapings, crusts and hair pluckings for

microscopic examination, smears, bacterial and fungal culture


Results

TestsTests

• Scrapings, crusts and hairs did not reveal ectoparasites or fungal structures; Dermatophilus was not demonstrated on microscopic examination

• Haematological and biochemical profiles were within accepted limits. The ANA test was negative

• Histopathology revealed a superficial pustular dermatitis. No micro-organisms were found in the lesions


What now?

TestsTests

• What treatment, if any, should you now institute whilst waiting for the fungal cultures?

• What are now your principle differential diagnoses?

• Are there any other samples you would collect?


Initial therapy

TherapyTherapy

• Ectoparasitism and neoplasia were deemed unlikely

• Autoimmune or immune-mediated disease seemed likely and the horse was deteriorating hence therapy was initiated

• Prednisolone, 0.5 mg/kg daily; trimethoprim and sulphadiazine (Uniprim), 0.5 sachet daily


What is yourdiagnosis?

TherapyTherapy

• What is your principle diagnosis?

• Do the investigations permit a definitive diagnosis?

• Are there any additional investigations which you think may need to be done?


Further tests

TherapyTherapy

• A superficial pustular dermatitis was present

• The pustules contained many neutrophils & acanthocytes but no micro-organisms

Histopathology


Diagnosis

TherapyTherapy

• Pemphigus foliaceus• Lesion type and histopathology are consistent• No history of previous drug therapy• Fungal culture was negative


How would you deal with this case?

• What is your prognosis?

• How will you advise the owner?

• What treatment would you consider?

TherapyTherapy


Response to therapy - 1

NotesNotes

• After 5 days the lesions were unchanged

• The prednisolone dose was increased to 300 mg per day and there was a moderate improvement over a period of 10 days - decreased scaling and some hair regrowth

• Steroid therapy lapsed (owner’s choice) and the horse’s condition remained stable over a two-month period but then again worsened


Response to therapy - 2

NotesNotes

• Prednisolone therapy at 300 mg twice daily (1 mg/kg b.i.d.) was resumed. Within 2 weeks all lesions had disappeared and after 1 month the horse was reported to be in good condition

• Attempts will be made to lower the dose over the coming months


Prognosis

NotesNotes

• Prognosis is guarded• The disease may require potent immunosuppressive

therapy with significant side effects• It may not respond adequately


Review

NotesNotes

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Crusting and exudation in a Welsh stallion pony Author: Mark CraigEditor: David Lloyd © European Society of Veterinary Dermatology