The approach to scale, crusting and nail disease

Question 1

What is scale?

Answer 1

The presence of flakes of keratin in the hair coat and on the skin

Question 2

Scale results from…? (5 options)

Answer 2

• Normal skin function (a little scale [dandruff] is normal in many situations)
• Abnormal desquamation (shedding of corneocytes)
• Abnormal cornification (creation of the outer epidermal layers)
• Inflammation (influences cell turnover and structures)
• Bacterial and fungal enzymatic action

Question 3

How does scale lead to crusts?

Answer 3

Crusts result from the hardening of pus, serum and/or blood with scale to form a solid material which is like scale is variably adherent to the skin

Question 4

What are some examples of disease where scale is primarily noted?

Answer 4

• Primary keratinization disorders
• Primary seborrhoea
• Zinc–responsive dermatosis
• Vitamin A-responsive dermatosis
• Ear margin seborrhoea

Question 5

What are some examples of disease where scale is secondarily noted?

Answer 5

• Callus (compact adherent scale)
• Hypothyroidism
• Allergy
• Parasites
• Bacterial infection
• Dermatophytosis
• Sebaceous adenitis

Question 6

How is scale managaed?

Answer 6

• Treat primary disease

- Manage scale by removing excess

Question 7

What is the role of bacteria in scale production?

Answer 7

Staphylococcus pseudintermedius causes a folliculitis and following rupture of the pustule and central hair loss a spreading circle of scale is seen moving from the central area
- The amount of scale depends on bacterial toxins

Question 8

What are some examples of non-specific topical treatments for scale, how do they work?

Answer 8

• Keratoplastic / keratolytic products: reduce scale production and remove scale
• Moisturizing and emollient products: reduce transepidermal water loss and prevent inflammation. best used after other products have removed scale

Question 9

What are some benefits of improving the skin surface?

Answer 9

• Reduce bacterial colonisation
• Reduce Malassezia numbers
• Reduce transepidermal water loss

Question 10

Which breed is predisposed to Zn-responsive dermatosis?

Answer 10

Husky

Question 11

What is the key histological finding for Zn-responsive dermatosis?

Answer 11

Parakeratosis

Question 12

What are the signs and features of Zn-responsive dermatosis?

Answer 12

• Genetic poor Zn absorption often young adult onset in the winter
• Dull coat and specific hard plaques with marked scale and crusting
• Crusted hyperkeratosis (bacterial infection common)
• Variable pruritis

Question 13

How can Zn-responsive dermatosis be treated?

Answer 13

Zinc supplementation, correct diet

Question 14

Which breed is predisposed to ichthyosis?

Answer 14

Golden retriever

Question 15

What are the signs and features of ichthyosis?

Answer 15

• Seen from a few weeks of age, scale is variable over life but can be severe
• Barrier function is not compromised so 2˚ infection is uncommon, but can get 2˚ otitis

Question 16

What are the clinical signs of ear margin seborrhoea?

Answer 16

• Adherent keratin on both medial and lateral sides of the pinna
• Follicular casts and plugs may trap hair
• Rubbing produces erosions and ulceration
• Pruritus variable

Question 17

How can ear margin seborrhoea be treated?

Answer 17

• Emollient rinses, Vaseline, propylene glycol

* Surgery to remove pinna margin

Question 18

What are the main presentations of nail disease?

Answer 18

• Nail breakage and loss
• Pus, inflammation and/or swelling of the nailbed (paronychia)
• Discolouration of the nail
• Pruritis

Question 19

Give some examples of diseases with nail loss and or breakage

Answer 19

• Symmetrical lupoid onychodystrophy
• Dermatophytosis
• Acute nail trauma
• Neoplasia of the ungual fold

Question 20

How does symmetrical lupoid onychodystrophy present in nail disease?

Answer 20

• Nail loss (onychomadesis)
• Nail breakage, nail splitting (onychorrhexis and onychoschizia)
• Nail pain (onychalgia)
• Haemorrhage within the nail
• Multiple nails and paws are affected with an acute or subacute onset

Question 21

How does dermatophytosis present in nail disease?

Answer 21

• Nail loss (less common than in SLO)
• Nail breakage (nail is invaded by fungal hyphae so often soft and crumbly
• Nail pain (onychalgia).
• Slow onset, starts in one area

Question 22

How is acute nail trauma treated?

Answer 22

• Removing loose or moving fragments of nail (painful – analgesia/sedation)
• Consider amputation for repeatedly traumatised dew claws (rare)
• Bandage to avoid pain and self-trauma

Question 23

Which two tumour types can cause neoplasia of the ungual fold?

Answer 23

Squamous cell carcinoma

Melanoma

Question 24

How does neoplasia of the ungual fold present?

Answer 24

Digital pain, swelling and in the event of involvement of the nail fold or P3 nail loss and may also show paronychia (skin infection)

Question 25

What are the different causes of paronychia?

Answer 25

Tumours, bacterial infection, Malassezia and immune-mediated diseases (especially pemphigus)

Question 26

How do nails appear in Malassezia overgrowth?

Answer 26

Stained - collar shape

Question 27

What consideration should be made when examining a patients nails?

Question 28

What are some diagnosis options for nail disease?

Answer 28

• Cytology from the nail fold (indirect impression smears using a fine swab are often best)
• Fungal culture should be performed in many cases
• Biopsy: when single or small numbers of digits fail to response to appropriate treatment for secondary infection