Seborrhoea and otitis in a crossbred dog

Seborrhoea and otitisin a crossbred dog

Author: Ross Bond

Editor: David Lloyd

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History - 1

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History

•9-year-old neutered female Collie cross dog

•Weight 43 kg

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

•Has always been overweight but gaining more inlast 2 years

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History - 2

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History

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

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

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

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

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History - 3

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History

•Neomycin + betamethasone drops for otitis - littleimprovement

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

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

•Efavet 660, 1 twice daily. No effect

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Clinical signs - 1

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Signs

•Bright, alert dog

•Heart rate 110 beats per minute

•Rectal temperature 38.1oC

•Mild generalised seborrhoea

•Mild erythema and hyperpigmentation ofinterdigital skin

•Moderate ceruminous otitis

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Clinical signs - 2

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Signs

•The dog wasoverweight

•The coat was long,thick and greasy

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Clinical signs - 3

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Signs

Anterior and dorsal views of the dog

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How would youapproach this case?

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Signs

•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 adefinitive diagnosis

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Case investigation

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Differentials

•Principle differential diagnoses

•Ewan - what would you include?

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Tests

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Tests

•Tests

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

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

•Blood tests

•Routine haematology

•Biochemistry panel

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Results

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Tests

•Scrapings did not reveal ectoparasites

•Tape strips demonstrated substantial numbers ofMalassezia in the interdigital spaces

•Haematological and biochemical profiles were withinaccepted limits

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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?

Tests

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Initial therapy

•Ectoparasitism was deemed unlikely

•Malassezia numbers indicated infection necessitatingtherapy

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

Tests

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What is yourdiagnosis?

•What is your principle diagnosis?

•Do the investigations permit a definitive diagnosis?

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

Tests

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Further tests

Tests

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•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?

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Diagnosis

•Hypothyroidism diagnosis supported by:

•Low total T4 and elevated TSH levels

•Dog overweight

•Poor exercise tolerance

•Susceptibility to skin infection

•Hypertrichosis

Tests

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How would you dealwith this case?

•What is your prognosis?

•How will you advise the owner?

•What treatment would you institute?

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Tests

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Prognosis

•Prognosis is good

•Hypothyroidism normally responds well to therapywith thyroxine

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

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Tests

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Therapy

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Therapy

•Thyroxine administered at 10 ug/kg twice daily for 12weeks then the 4 hour post-T4 basal plasma total T4measured and gave a value of 35 nmol/l

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

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

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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

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Therapy

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Points to consider - 1

Notes

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•How do you asses the significance of Malassezia

•Tape strips and surface culture methods only identifysuperficial populations. Some cases withoutelevated surface populations will respond to anti-yeast therapy

•Could ketoconazole have been used to deal with theMalassezia?

•Signs were mild and did not justify ketoconazole anunlicensed product.

•Ketoconazole inhibits steroidogenesis and wouldhave complicated the interpretation of subsequentendocrine assessments

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Points to consider - 2

Notes

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•Why is hypertrichosis sometimes a feature ofhypothyroidism?

•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

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Review

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Notes

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