Approach to alopecia Flashcards
What is the definition of alopecia?
A lack of hair in normally hairy areas
What are the two pathogenesis of alopecia?
- Failure of follicel to grow hair
- Loss of existing hair
What are two examples of ‘lack of follicles’ ?
- Alopecia Hypotrichosis
- Canine Ectodermal Dysplasia
What is follicle dysplasia?
A group of often ill-defined alopecia disorders that are frequently linke dto coat colouring
What is structural follicular dysplasia?
Disorder of follicle development that affects young to middle aged dogs
Weak hairs then break easily
Usua
What is colour dilution alopecia?
Blue/ Fawn coated breeds
Melanocyte dysfunction in the follicle
Coat is normal at birth -> starts losing hair at 6 months to 2 years
What is black hair follicular dysplasia?
Rare
Occurs in black haired areas
Associated with defective pigmentation
Puppies are normal at birth
Similiar to colour dilution
What is cyclical follicular dysplasia?
Often occurs in autumn or spring
2-4 years of age
Hair can regrow
What may assist with cyclical follicular dysplasia?
Melatonin administration
Prophylactic use may also help
What is atrophic follicular patterns baldness?
characterised by the miniaturisation of follicles
* associated with short-coated breeds
* different patterns= ears, ventral abdomen and chest, thighs
* Often starts in late puberty
* Dachsshund, Chihuahua, Sight hounds
* May progress to complete alopecia (skin becomes hyperpigmented)
What is idiopathic bald thigh syndrome of greyhounds?
Caused by structural hair shaft defects
Associated with downregulation of genes
Usually in young adults
Complex mode of inheritance
How does an endocrine disease cause an abnormal follicle cycle?
- Several hormones are involved in the maintenance of healthy follicle and hair growth
- Hairs arrest in telogen
What is alopecia X in dogs?
- Hair cycle arrests
- Primary hairs are affected first
- Gradual hair loss over the trunk and caudal thighs
- Spares the head and forelimbs
- Thought to be an adrenal sex hormone imbalance
- Breed predisposition = poodles and pomeranians (2-5 years of age)
How would you treat alopecia in dogs?
Thyroxine, Trilostane, Melatonin, Castration, Deslorelin
Give a couple of examples of systemic diseases that cause an abnormal follicle cycle?
- Hepatic disease
- End Stage Renal Disease
- Pancreatic Disease
- Neoplasia
What two drug therapies can cause an abnormal follicle cycle?
- Cytotoxic drugs
- Steroids
What is telogen effluvium?
Stressful event causes abrupt cessation of hair growth in the anagen phase
Hair follicles then become synchronised in the telogen phase
2-3 months after the event the telogen hairs shed
What 4 things can cause damage to follicles?
- Infection
- Immune Mediated Disease
- Neoplasia
- Trauma
- Tail gland hyperplasia
What is sebaceous adenitis?
Autoimmune response against sebaceous glands in hair follicles
Usually in young to middle aged dogs
Variety of treatments= VIT A, EFA’s cyclosporine
What is the drug reaction to immune mediated disease?
- Topical reaction or injection site reaction
- Hair loss may be immediated or delayed and may not regrow
What is alopecia areata?
- rare
- multifocal patchy hair loss
- affects many animals
- autoantibodies directed against hair follicle proteins
- Hair regrowth is often spontaneous
What is feline psychogenic alopecia?
- Hair loss and/or skin damage resulting from displacement grooming in reaction to stressors
- Diagnosis of exclusion = when all medical conditions are ruled out
- Address the associated stressors
- Use desensitisation and counterconditioning techniques to deal with any underlying fears
- Treatment is only effectivce with behavioural modification
What breeds are most likely to be affected by structural follicular dysplasia?
- Irish water spaniel
- Portugese water dog
- Doberman
- Weirmaner
What dogs are genetically predisposed to cyclical follicular dysplasia?
- Boxers
- Bulldogs
- Airedales
- Schnauzers
When does atrophic follicular pattern baldness usually start
- Often starts in late puberty
- may progress to complete alopecia
- skin may become hyperpigmented over time
What causes hyperestrogenism?
abnormal follicle cycle
Male dogs with Sertoli cell tumours
* castrate
* Bitches with cystic ovaries
* spay
What causes pituitary dwarfism?
Inadequate secretion of growth hormone
* Retardation of growth and progressive hair loss
* Genetic predisposition in GSD’s
* Treatment: growth hormone £££££
* Progestogens and thyroxine, but side effects
What causes alopecia in dogs?
Hair cycle arrest
* Primary hairs affected first – soft, downy secondary hairs remain
* Gradual hair loss over trunk and caudal thighs
* Sparing head and forelimbs
* Thought to be adrenal sex hormone imbalance
* Similarity with hyperoestrogenism
* Breed predisposition
* Poodle; Pomeranian (and arctic breeds)
* 2-5 years of age
* Treatment: thyroxine, trilostane, melatonin, castration, deslorelin – side effects* Aesthetic concern only
What kind of systemic disease may interrupt the hair growth cycle?
- Hepatic disease
- End-Stage Renal Disease
- Pancreatic disease
- Neoplasias
Name a bacterial infection that causes follicle damage?
Dermatphilus congolensis
What is sebaceous adenitis?
Autoimmune response against sebaceous glands in hair follicles
* Genetic predisposition; mostly seen in dogs; rarely in other mammals* Young to middle aged dogs
* Two expressions in dogs
* Long coated breeds – poodle, Akita, Samoyed – lesions ears, back and flanks* Short coated breeds – Viszla – facial lesions and generalised moth-eaten lesions* Variety of treatments: Vit A; EFAs; cyclosporine
* Secondary infections common – bacterial/fungal
What is alopecia areata?
Multifocal patchy hair loss
* Affects many animals
* In dogs often symmetrical, affecting face, head and legs
* Autoantibodies directed against hair follicle proteins
* Hair regrowth is often spontaneous (one paper cited remission in 60% of
cases) – regrowth may be lighter (non-pigmented)
* Resistant cases usually respond to corticosteroids or cyclosporin
What is feline psychogenic alopecia?
Hair loss and/or skin damage resulting from displacement
grooming in reaction to stressors which may be emotional or
environmental.
* Diagnosis of exclusion –made when all medical differentials ruled out
* Since psychogenic alopecia is a multifactorial condition, treatment will need to be
tailor made for each case
* Address associated stressors
* Increase stability of the emotional and physical environment of the cat
* Use desensitization and counterconditioning techniques to deal with any
underlying fears or phobias relating to specific stimuli.
* In severe cases psychopharmacology may be needed for example with tricyclic
antidepressants or serotonin reuptake inhibitors (SSRIs).
* Treatment will only be effective in combination with behavioural modification
