23.11.3: Scale disease

Question 1

What is scale and what does it result from?

Answer 1

Scale: presence of flakes of keratin in the hair coat and on the skin. Scale may be adherent (well attached to the epidermis) or loosely attached.

Scale results from:
* Normal skin function (a little scale a.k.a. dandruff = normal in many situations)
* Abnormal desquamation (shedding of corneocytes)
* Abnormal cornification (creation of the outer epidermal layers)
* Inflammation (inflammation induces cell turnover)
* Bacterial and fungal enzymatic action

Question 2

Diseases in which scale is noted
1

Answer 2

Question 3

Diseases in which scale is noted
2

Answer 3

Question 4

Which is more common: primary or secondary scale?

Answer 4

Secondary scale is very much more common than primary disease.

Question 5

Diagnostic plan for animal presented with scaling disease
1-5

Answer 5

Question 6

Signalment and presentation of Zinc-responsive dermatosis

Answer 6

Signalment
* Genetically predisposed breeds e.g. Huskies have Type I = genetic poor absorption of zinc
* Often young adult onset in winter
* Type II = nutritional restriction in young, rapidly growing large breeds
* Beware concurrent hypothyroidism (older animals, later onset)

Clinical presentation
* Dull coat and specific hard plaques with marked scale and crusting; lesions occur wherever dog knocks itself
* Crusted hyperkeratosis (bacterial infection common) -> lift crust and do cytology to check for infection
* ± Bacterial infection
* Variable pruritus, more so if infected

Question 7

Answer 7

Zinc responsive dermatosis

Question 8

Histological findings with zinc-responsive dermatosis

Answer 8

• Parakeratosis is a key finding
• Nuclei are retained in the stratum corneum; this is seen to a lesser extent in bacterial pyoderma and in superficial necrolytic dermatitis
• Zinc is required for normal keratinisation -> disease most common at areas of trauma

Question 9

Treatment of zinc-responsive dermatosis

Answer 9

• Zinc supplementation - Zinc sulphate traditionally used but may cause vomiting
• Correct diet
• Consider steroids if Type I and poor response (hard to get enough zinc into a husky, a tiny amount of anti-inflammatory dose steroids help but we don’t know how)

Question 10

History and clinical presentation of ichthyosis of Goldern Retrievers

Answer 10

• Seen from a few weeks old; scale variable over life but can be severe; need to rule out ectoparasites as a ddx
• Barrier function is not compromised -> secondary infection is uncommon, secondary otitis can occur
• Genetic disease, recessive allele -> genetic testing recommended

Question 11

Treatment of ichthyosis of Golden Retrievers

Answer 11

• Symptomatic treatment only
• Manage with shampoos
• Vitamin A-like analogues (retinoids) used with some success but quite severe drugs

Question 12

Signalment and clinical presentation of canine ear margin seborrhea

Answer 12

• Relatively uncommon
• Marked breed predilection in Dachshunds
• Can be a feature of hypothyroidism
• Adherent keratin on both medial and lateral sides of the pinna
• Follicular casts and plugs may trap hair
• Rubbing produces erosions and ulceration
• Pruritus is variable
• Fissuring and secondary infection can be problematic

Question 13

Differential diagnoses for canine ear margin seborrhea

Answer 13

• Secondary causes of pinnal seborrhea
• Hypothyroidism
• Trauma due to pinnal flapping
• Early vasculitis
• Early localised scabies

Question 14

Diagnosis and treatment of canine ear margin seborrhea

Answer 14

Question 15

Important differential diagnoses for nasodigital hyperkeratosis

Answer 15

There are many possible ddx. Important ones:
* Superficial necrolytic dermatitis - would expect animal to be painful, systemically unwell, and more widespread disease
* Epitheliotropic cutaneous lymphoma - hypopigmentation, ulceration, progression beyond the nose and pads
* Demodicosis (foot pad disease) - rare, look for signs of mites elsewhere on the dog

Question 16

Signalment of nasodigital hyperkeratosis

Answer 16

Nasodigital hyperkeratosis: broad term for dogs with non-iflamed, quiescent and tightly adherent hyperkeratosis affecting the nose and sometimes the feet.
* Usually older dogs
* No sex or breed predisposition
* Probably a senile change

Question 17

Clinical signs of nasodigital hyperkeratosis

Answer 17

• Nasal lesions can be variable: frond-like projections or hard surface. Nose is dry, and cracks and fissures can occur and lead to irritation.
• Pad lesions: all pads affected, and most prominent at edges due to weight bearing. Lack of flexibility of pad leads to cracking, formation of corns, lameness.

Question 18

Answer 18

Nasodigital hyperkeratosis

Question 19

Diagnosis of nasodigital hyperkeratosis

Answer 19

Question 20

Treatment of nasodigital hyperkeratosis

Answer 20

• Cut off prominent fronds with scissors or scalpel blade
• Hydrate the keratin using shampoos and soaks
• Essential fatty acids PO

Question 21

Answer 21

Nasal parakeratosis of Labrador Retrievers

Question 22

History and clinical signs of Nasal parakeratosis of Labrador Retrievers

Answer 22

Question 23

Differential diagnoses, diagnosis and treatment of nasal parakeratosis of Labrador Retrievers

Answer 23

Question 24

History and clinical signs of footpad hyperkeratosis of Dogue de Bordeaux

Answer 24

There is popilteal and prescapular LN enlargement in cases of pedal infection (where the skin has split and enabled bacterial infection)

Question 25

Answer 25

Footpad hyperkeratosis of Dogue de Bordeaux

Question 26

Diagnosis and treatment of footpad hyperkeratosis of Dogue de Bordeaux

Answer 26

Question 27

Where are calluses typically formed? If they are found elsewhere, what might this tell you about your patient?

Answer 27

• Often found over hocks, elbows, sternum, ischium
• Callus = normal response to pressure-induced ischaemia and inflammation
• Secondary infection is common
• Other areas involved - may suggest orthopaedic problems or hypothyroidism

Question 28

Diagnosis and treatment of calluses

Answer 28

Diagnosis
* Typical clinical signs and position
* Can perform skin surface and exudate cytology -> bacterial cylture
* Can perform biopsy if needed for tissue culture

Treatment
* Treat secondary infection
* Remove trauma / pressure
* Consider bandaging and padding
* Surgery can help but need to consider if post-surgery the same factors that caused the callus will remain and lead to breakdown of the wound

Question 29

Signalment and clinical signs of thymoma-induced exfoliative dermatitis

Answer 29

This is a cutaneous marker of systemic disease.

Question 30

Diagnosis and treatment of thymoma induced exfoliative dermatitis

Answer 30

Question 31

You think you have diagnosed a dog with idiopathic canine sebaceous adenitis, but then you suddenly realise it has previously travelled abroad. What do you now need to consider?

Answer 31

Histological sebaceous adenitis can be seen in a variety of disease but particularly Leishmaniasis

Question 32

Pathogenesis of idiopathic sebaceous adenitis

Answer 32

Question 33

Clinical signs and diagnosis of idiopathic sebaceous adenitis

Answer 33

Question 34

Answer 34

Idiopathic canine sebaceous adenitis

Question 35

Treatment of idiopathic canine sebaceous adenitis

Answer 35

Question 36

2 major categories of treatment for scaling disease

Answer 36

Question 37

1 and 2

Answer 37