The approach to scale, crusting and nail disease Flashcards
What is scale?
The presence of flakes of keratin in the hair coat and on the skin
Scale results from…? (5 options)
- 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
How does scale lead to crusts?
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
What are some examples of disease where scale is primarily noted?
- Primary keratinization disorders
- Primary seborrhoea
- Zinc–responsive dermatosis
- Vitamin A-responsive dermatosis
- Ear margin seborrhoea
What are some examples of disease where scale is secondarily noted?
- Callus (compact adherent scale)
- Hypothyroidism
- Allergy
- Parasites
- Bacterial infection
- Dermatophytosis
- Sebaceous adenitis
How is scale managaed?
- Treat primary disease
- Manage scale by removing excess
What is the role of bacteria in scale production?
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
What are some examples of non-specific topical treatments for scale, how do they work?
- 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
What are some benefits of improving the skin surface?
- Reduce bacterial colonisation
- Reduce Malassezia numbers
- Reduce transepidermal water loss
Which breed is predisposed to Zn-responsive dermatosis?
Husky
What is the key histological finding for Zn-responsive dermatosis?
Parakeratosis
What are the signs and features of Zn-responsive dermatosis?
- 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
How can Zn-responsive dermatosis be treated?
Zinc supplementation, correct diet
Which breed is predisposed to ichthyosis?
Golden retriever
What are the signs and features of ichthyosis?
- 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
What are the clinical signs of ear margin seborrhoea?
- 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
How can ear margin seborrhoea be treated?
- Emollient rinses, Vaseline, propylene glycol
* Surgery to remove pinna margin
What are the main presentations of nail disease?
- Nail breakage and loss
- Pus, inflammation and/or swelling of the nailbed (paronychia)
- Discolouration of the nail
- Pruritis
Give some examples of diseases with nail loss and or breakage
- Symmetrical lupoid onychodystrophy
- Dermatophytosis
- Acute nail trauma
- Neoplasia of the ungual fold
How does symmetrical lupoid onychodystrophy present in nail disease?
- 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
How does dermatophytosis present in nail disease?
- 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
How is acute nail trauma treated?
- 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
Which two tumour types can cause neoplasia of the ungual fold?
Squamous cell carcinoma
Melanoma
How does neoplasia of the ungual fold present?
Digital pain, swelling and in the event of involvement of the nail fold or P3 nail loss and may also show paronychia (skin infection)
What are the different causes of paronychia?
Tumours, bacterial infection, Malassezia and immune-mediated diseases (especially pemphigus)
How do nails appear in Malassezia overgrowth?
Stained - collar shape
What consideration should be made when examining a patients nails?
What are some diagnosis options for nail disease?
- 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
