3. Skin diseases - Alopecia Flashcards
What is alopecia?
Complete or partial lack of hairs (where they normally are present)
What is important to remember when it comes to Alopecia?
It is a CLINICAL SIGN and NOT a disease
What are the 4 type of alopetic divisions according to areas where it is spread on skin?
- Localized
- Multifocal
- Regional (facial, truncal, limb)
- Generalized
What is the two basic classifications of alopecia?
Hereditary or Acquired
Name a few causes for development of Alopecia?
Most commonly - Pruritic skin disease and associated with self-trauma
- Self-trauma from pruritus caused by
- ectoparasitic disease
- microbial infections
- hypersensitivities
- Folliculitis as a result of staphylococcal infections, dermatophytosis, demodicosis or autoimmune folliculitis
- Failure of hair growth cycle → Endocrinopathy.
What are the classification of hereditary alopetic skin diseases?
- Dystrophy or abscence of hair follicles
- Abnormalities in the hair shaft structure
What is Hereditary hypotrichosis?
- A congenital non-colour linked alopetic disorder that gives less hair than normal.
What is typical for Hereditary hypotrichosis?
- Generalized truncal alopecia at birth is typical
- Mild secondary pyoderma or seborrea may develop in dogs, comedones are common
- Rare in both dogs and cats except in Alopetic bred breeds
How can Hereditary hypotrichosis be treated?
There is no treatment for the alopecia itself since they are bred for this appearance.
But anti-bacterial schampoos for the secondary seborrhea or pyoderma can be used - Anti-seborrheic follicular flusing
What is Canine primary seborrhea?
Belonging to what type of alopecia?
- A hereditary disorder of keratinization
- Hereditary Alopecia - Dystrophy or abscence of hair follicles
What are clinical signs of Canine Primary Seborrhoea?
Begin at a young age / puppyhood as mildly and worsens with age
Dull, dry hair coat, excessive scaling (dandruff), variable pruritus and crusty seborrheic patches.
Most of the body is involved.
- interdigital areas
- perineum
- face, axillae, ventral neck
- abdomen and skin folds usually most severely affected
- ceruminous otitis externa is common.
The animal usually has secondary infection with Malassezia (distinct smell).
Which hereditary alopetic skin diseases belongs to “Abnormalities in the hair shaft structure”?
- Follicular dysplasia
- Pattern alopecia
- Recurrent alopecia (canine recurrent flank alopecia)
- Sebaceous adenitis
- Epidermal dysplasia of West Highland White Terriers
What is follicular dysplasia?
A group of genetic dermatoses characterized by a structural hair follicle abnormality –> resulting in alopecia
Why is it important to know about Follicular dysplasias?
They are important for differential diagnosis from all the endocrine alopecia
What are age and breed predisposition of Follicular dysplasia?
- Dermatological signs starts in YOUNG dogs and progress slowly
Siberian Husky and Malamute FD – Several puppies in same liter. Reach 3 months of age, hairs on trunk become reddish and falling out gradually.
Irish water spaniel – Alopecia starts between 2 – 4 years of age mainly neck, dorsolumbar region and tail BEFORE spreading to the trunk.
What are clinical signs of follicular dysplasia?
- Dermatological signs start in young dogs and slowly progress.
- “Moth eaten” appearance across the dog’s trunk.
- Scaly skin
Head and limbs usually unaffected!!!!!
What is the most common genetic/hereditary dermatosis disease in dogs?
Color-dilution alopecia (Follicular dysplasia belonging to Abnormalities in the hair shaft structure)
Give an example of a color-diluted alopecia?
Black hair follicular dysplasia
Which dogs are most commonly affected by CDA?
CDA = Color-Dilution Alopecia
In dogs with blue/black coats - especially in Doberman but also in YT, Great Dane, Dachshund, Salukis
What is thought to be the reason for development of black hair follicular dysplasia?
Poor understood but,
* Primary hair follicle dysfunction
* Abnormal melanosome transfer to keratinocytes also suscpeted in Dobermann
* Melatonin stimulating hormone deficiency
When do clinical signs usually appear in CDA/Black hair follicular dysplasia?
Usually between 4 months and 3 years old
What are clinical signs of black hair follicular dysplasia starting at early age?
Progressive hypotrichosis
Extensive alopecia of pigmented regions, mainly on trunk
- Short, dry, lusterless hair
- Head and limbs are often not affected or much later in life
What is common secondary development from Black hair follicular dysplasia?
Pyoderma in dorsolumbal region and may cause pruritus
Name the non-inflammatory alopecias
- Pattern Alopecia
- Recurrent flank Alopecia
Describe Pattern alopecia
- Unknown aetiology but a common dermatosis a genodermatoses. Non-inflammatory alopecia
- Belonging to Hereditary alopecia (Abnormalities in the hair shaft structure)
What are clinical signs to Pattern alopecia?
Alopecia start around 6-12 months of age on convex pinnae, ventral neck, thorax, caudal thighs, abdomen and tail.
Gradually progressing over the years but remaining localized.
What is thought to be reason for development of Recurrent flank alopecia?
Unknown aetiology but suspect,
- Seasonal follicular dysfunction
- Influence of photoperiod (Melatonin and Prolactin two photo-dependent hormonens involved in hair growth)
What are clinical signs of recurrent flank alopecia?
- Non-pruritic, non-inflamed
- Well-defined bordered alopecia limited to the thoracolumbar region that is often unilateral.
- Skin is often hyperpigmented.
- Cyclical alopecia of convex pinnae, bridge of nose and caudal thighs.
- Similar to Pattern Alopecia which is NOT cyclical
What is Sebaceous adenitis?
Poorly understood. A destructive inflammatory disease of sebaceous gland
What characterizes Sebaceous adenitis?
Mild or severe scaling of head, face, ear, neck, dorsum and tail.
Sebum production = moist alopecia with potential pruritus.
Pruritus if secondary Malassezia infection.
How can the skin disease Sebaceous adenitis be spread on body?
May remain localized, be multifocal or general over trunk
In which breeds are Sebaceous adenitis thought to be an autosomal recessive disease?
Poodles and Akitas
How can Sebaceous adenitis be treated?
- Essential FA
- Prednisone (corticosteroid)
- Vitamin A
- Antimitotic ATB
Any secondary bacterial or Malassezia infection should be treated with appropriate systemic medication.
What is special with West Highland White Terriers?
They are the only breed with having inherited disorder of keratinization (dysplastic epidermis) which is predisposed to secondary Malassezial infection and allergy
What is Epidermal dysplasia?
Severe chronic dermatosis
Characterized by pruritus, seborrhea and lichenification
Occurihg in West Highland White Terriers
What are clinical signs of Epidermal dysplasia?
- Development of greasy hair coat
- Moderate pruritus of face, ears, limbs, feet and ventral body.
As it becomes chronic:
- Intensified pruritus
- Widespread pyoderma – > alopecia, scaling, crusting, lichenification and hyperpigmentation
Name classification of acquired alopecia
Divided into traumatic and non-traumatic.
Traumatic:
* Pruritic dermatoses
* Physical and chemical assault
Non-traumatic: (NOT PRURITIC)
* Endochrinopathy
* Tumors
Name 4 acquired alopecia diseases except the traumatic and non-traumatic ones.
- Canine Pattern Baldness
- Idiopathic Bald Thigh Syndrome
- Feline Preauricular and Pinnal Alopecias
- Demodicosis
Is Follicular dysplasia genetic or not? Which endocrinological disease is it similar to?
Suspected and has been genetically proven in some cases.
Similar to Hypoestrogonism
