Seborrhoea and otitis in a crossbred dog Author: Ross BondEditor: David Lloyd © European Society of Veterinary Dermatology

Seborrhoea and otitis in a crossbred dog

Author: Ross BondAuthor: Ross Bond 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

• 9-year-old neutered female Collie cross dog

• Weight 43 kg

• Has had a dull, somewhat greasy coat for 4 years or more

• Has always been overweight but gaining more in last 2 years


History - 2

HistoryHistory

• Decreased exercise tolerance attributed by owners to weight gain and arthritis (reluctance to exercise)

• Mild, recurrent head tremor noted on several occasions in the past year

• Chews and licks feet but not a severe problem, has itchy ears

• Dog is bright, appetite good, thirst unchanged (1.8-2.0 litres/day)


History - 3

HistoryHistory

• Neomycin + betamethasone drops for otitis - little improvement

• Etiderm (ethyl lactate shampoo) - resolved pedal pruritus but erythema remained. Relapse after 6 weeks

• Prednoleucotropin (PLT), 1-2 twice daily for arthritis. Some improvement

• Efavet 660, 1 twice daily. No effect


Clinical signs - 1

SignsSigns

• Bright, alert dog

• Heart rate 110 beats per minute

• Rectal temperature 100.5oC

• Mild generalised seborrhoea

• Mild erythema and hyperpigmentation of interdigital skin

• Moderate ceruminous otitis


Clinical signs - 2

SignsSigns

• The dog was overweight

• The coat was long, thick and greasy


Clinical signs - 3

SignsSigns

Anterior and dorsal views of the dog


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


Case investigation

DifferentialsDifferentials

• Principle differential diagnoses• Ewan - what would you include?


Tests

TestsTests

• Tests

• Skin scrapings from feet ..... Ewan where else?

• Tape strips from interdigital spaces ......?

• Blood tests• Routine haematology• Biochemistry panel


Results

TestsTests

• Scrapings did not reveal ectoparasites

• Tape strips demonstrated substantial numbers of Malassezia in the interdigital spaces

• Haematological and biochemical profiles were within accepted limits


What now?

• What treatment, if any, should you now institute?

• What are now your principle differential diagnoses?

• Are there any other samples you would collect?

TestsTests


Initial therapy

• Ectoparasitism was deemed unlikely

• Malassezia numbers indicated infection necessitating therapy

• Owner was instructed to bathe the feet using Malaseb Shampoo twice weekly. Allowing a 10 minute contact time before rinsing.

TestsTests


What is yourdiagnosis?

• 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?

TestsTests


Further tests

TestsTests

• Total T4 and endogenous TSH were measured,

• Results

• Total T4 = 12.7 µmol/l (13-52)

• Endogenous TSH = 0.47 µg/ µl (<0.41)

• What does this mean?


Diagnosis

• Hypothyroidism diagnosis supported by:

• Low total T4 and elevated TSH levels

• Dog overweight

• Poor exercise tolerance

• Susceptibility to skin infection

• Hypertrichosis

TestsTests


How would you deal with this case?

• What is your prognosis?

• How will you advise the owner?

• What treatment would you institute?

TestsTests


Prognosis

• Prognosis is good• Hypothyroidism normally responds well to therapy

with thyroxine

• Hypothyroidism may explain many, if not all of the clinical problems in this case

TestsTests


Therapy

TherapyTherapy

• Thyroxine administered at 10 ug/kg twice daily for 12 weeks then the 4 hour post-T4 basal plasma total T4 measured and gave a value of 35 nmol/l

• Maintenance therapy was then established at 15 ug/kg of thyroxine twice daily

• Response. Loss of all hair apart from a short 2-3 cm coat, over a 3 month period


Response to therapy

• Coat then grew gradually to form a normal coat

• Weight decreased to 32kg over 12 months

• Exercise tolerance and mobility improved

• Head tremor absent

• Coat improved but still some greasiness

• Continuing mild otitis externa

• No pruritus

TherapyTherapy


Points to consider - 1

NotesNotes

• How do you asses the significance of Malassezia• Tape strips and surface culture methods only identify

superficial populations. Some cases without elevated surface populations will respond to anti-yeast therapy

• Could ketoconazole have been used to deal with the Malassezia?

• Signs were mild and did not justify ketoconazole an unlicensed product.

• Ketoconazole inhibits steroidogenesis and would have complicated the interpretation of subsequent endocrine assessments


Points to consider - 2

NotesNotes

• Why is hypertrichosis sometimes a feature of hypothyroidism?• Thought to be caused by slowed hair cycle turnover -

telogen hairs not shed and resultant thick coat

• It is a common feature of equine hypothyroidism

• In dogs it is seen particularly in setters


Review

NotesNotes

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Seborrhoea and otitis in a crossbred dog Author: Ross BondEditor: David Lloyd © European Society of Veterinary Dermatology