Transcript Case of the Month - Ross Bond

Seborrhoea and otitis
in a crossbred dog
Author: Ross Bond
Editor: David Lloyd
© European Society of Veterinary Dermatology
History - 1
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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
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History | Signs | Differentials | Tests | Therapy | Notes
History - 2
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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 | Signs | Differentials | Tests | Therapy | Notes
History - 3
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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
History | Signs | Differentials | Tests | Therapy | Notes
Clinical signs - 1
• 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
History | Signs | Differentials | Tests | Therapy | Notes
Clinical signs - 2
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The dog was
overweight
The coat was long,
thick and greasy
History | Signs | Differentials | Tests | Therapy | Notes
Clinical signs - 3
Anterior and dorsal views of the dog
History | Signs | Differentials | Tests | Therapy | Notes
How would you
approach this case?
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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
History | Signs | Differentials | Tests | Therapy | Notes
Case investigation
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Principle differential diagnoses
• Ewan - what would you include?
History | Signs | Differentials | Tests | Therapy | Notes
Tests
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Tests
• Skin scrapings from feet ..... Ewan where else?
• Tape strips from interdigital spaces ......?
• Blood tests
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Routine haematology
Biochemistry panel
History | Signs | Differentials | Tests | Therapy | Notes
Results
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Scrapings did not reveal ectoparasites
Tape strips demonstrated substantial numbers of
Malassezia in the interdigital spaces
Haematological and biochemical profiles were within
accepted limits
History | Signs | Differentials | Tests | Therapy | Notes
What now?
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What treatment, if any, should you now institute?
What are now your principle differential diagnoses?
Are there any other samples you would collect?
History | Signs | Differentials | Tests | Therapy | Notes
Initial therapy
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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.
History | Signs | Differentials | Tests | Therapy | Notes
What is your
diagnosis?
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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?
History | Signs | Differentials | Tests | Therapy | Notes
Further tests
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Total T4 and endogenous TSH were measured,
Results
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What does this mean?
• Total T4 = 12.7 µmol/l (13-52)
• Endogenous TSH = 0.47 µg/ µl (<0.41)
History | Signs | Differentials | Tests | Therapy | Notes
Diagnosis
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Hypothyroidism diagnosis supported by:
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Low total T4 and elevated TSH levels
Dog overweight
Poor exercise tolerance
Susceptibility to skin infection
Hypertrichosis
History | Signs | Differentials | Tests | Therapy | Notes
How would you deal
with this case?
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What is your prognosis?
How will you advise the owner?
What treatment would you institute?
History | Signs | Differentials | Tests | Therapy | Notes
Prognosis
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Prognosis is good
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Hypothyroidism normally responds well to therapy
with thyroxine
Hypothyroidism may explain many, if not all of the
clinical problems in this case
History | Signs | Differentials | Tests | Therapy | Notes
Therapy
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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
History | Signs | Differentials | Tests | Therapy | Notes
Response to therapy
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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
History | Signs | Differentials | Tests | Therapy | Notes
Points to consider - 1
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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 antiyeast 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
History | Signs | Differentials | Tests | Therapy | Notes
Points to consider - 2
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Why is hypertrichosis sometimes a feature of
hypothyroidism?
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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
History | Signs | Differentials | Tests | Therapy | Notes
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History | Signs | Differentials | Tests | Therapy | Notes