Non-inflammatory Alopecia Flashcards
T/F: alopecia is typically infectious (folliculitis) but it is not always
True
What are the stages in the hair cycle
1) Anagen - growth phase
2) Catagen- transition
3) Telogen- resting
4) Exogen- release/ shedding
What are the influeneces of the hair cycle
1) External: photoperiod, ambient temperature, nutrtion
2) Genetic
3) Hormonal
4) Neuronal
5) Immunologic
6) Cellular (mast cells, macrophages)
7) Signaling (growth factors, cytokines)
What endocrinopathies cause alopecia
1) Hyperadrenocortisim (spontaneous, atypical, iatrogenic)
2) Hypothyroidism
3) Sex hormone imbalances ( Testicular neoplasia, cystic ovaries, ovary neoplasia, estrogen exogenous supplementation), sex hormone producing adrenal tumors
4) Grown hormone deficiency (pituitary dwarfism)
5) Diabetes mellitus (maybe secondary to bacterial pyoderma)
*skin biopsies not particularly useful for differentiation
What might cause sex hormone imbalances leading to alopecia
-Testicular neoplasia (ie sertoli cell tumor)
-Cystic ovaries
-Ovarian neoplasia
-Exogenous supplementation (estrogen)
-Sex hormone producing adrenal tumors (ie progestens)
-Contact with sex hormone topicals used by owners
T/F: skin biopsies are not particularly useful for differentiation of endocrinopathy causes of alopecia
True
How can hormone imbalances effect the coat
1) Hair follicle cycle abnormalities
-Telogenization of follicles (stuck in resting phase)
-Failure to regrow after clipping
-Hair loss
2) Hanges in hair quality- coarse and frizzy
3) Changes in coat color- bleaching or darkening
Alopecia due to hormone imbalances is typically
bilaterally symmetrical truncal/ tail coat thinning
sparing the head and distal extremities
What signs might you see of disordered keratinization from hormone imbalances
1) Hyperkeratosis- thickening of stratum corneum
2) Scaling/seborrhea
3) Comedo (black head formation)
non-specific
Hair due to hormone imbalance will be
dull, dry, brittle +/- texture and color change
changes in hair thickness (atrophy) is seen with
hyperadrenocorticism
excess progestogen exposure
diabetes mellitus
alopecia or coat thinning due to hormone imbalances is typically spared at the
head and distal extremities
If you see a comedone in a cushing’s patient, why might you also want to diagnostically work the case up more
even though HAC can cause comedones, they are also immunocompromised which demodex could also cause comedones
With HAC, you can see cutaneous atrophy, what is that
often first noted in areas of old scars
striae (stretch marks)- ventrum
visible blood vessels
palpably thin
loss of elasticity
calcinosis cutis
vascular proliferations often seen in Cushing patients
differential for hemangiomas
might want to biopsy if cushings not diagnosed
Phlebectasia
What should you beware of with long-term, daily, low dose prednisone or prednisolone for allergy management, daily budesonide for IBD, and hgiher dose daily or EOD therapy for immune mediated disease
Iatrogenic hyperadrenocorticism
Alopecia over the bridging of the nose makes you suspicious for
Hypothyroidism
T/F: rat tail hypotrichosis is specific for hypothyroidism
False
What are the hypometabolic skin changes seen with hypothyroidism
1) Hyperkeratotic- thickening of stratum corneum (panum and areas of wear)
2) Epidermis normal to thickenined
3) Dermis normal to thickened
+/- mucin accumulation in dermis
What are your differentials for paw pad hyperkeratosis
1) Hypothyroidism
2) Zinc responsive dermatosis
3) Superficial Necrolytic Dermatosis (Liver failure)
4) Pemphigus
5) Idiopathic
With endocrinopathies, what might you see with response to therapy
May see initial - gets worse before better
1) Increased shedding/exfoliative dermatitis, scaling 3-6 weeks into treatments
2) Initial hair regrowth - often darker
Best normalization of coat/skin associated with optimal control:
-TT4 high normal to slightly supra-normal on BID therapy
-Cortisol normalized
How long does it take for the skincoat to get better after treating endocrinopathies
by about 3-6 weeks
With treating endocrinopathies, you get the best normalization of coat/skin with
1) TT4 high normal to slightly supra-normal on BID therapy
2) Cortisol normalized
Perianal adenomas/adenocarcinomas
excess androgen produced from testicular tumors or adrenals
hyperplasia of circumanal glands and tail glands
-regress after neutering
Sertoli cell tumors have the highest incidence in
cryptorchid
the non-neoplastic testicle is usually atrophied
What 6 things do you see with Sertoli cell tumor
1) Non-neoplastic testicle is usually atrophied
2) Feminization
3) Aspermatogenesis
4) Prostatic disease
5) Bone marrow hypoplasia
6) Linear preputial erythema or hyperpigmentation
Metastatic disease is uncommon
What might you see with hyperestrogenism due to cystic ovaries
1) Caudal thighs, ventrum, flank alopecia that may become truncal
2) Gynecomastia
3) Abnormal estrous cycles (prolonged or shortened)
What causes iatrogenic hyperestrogenism
chronic contact with human topical hormone replacement (estrogen)
What might resolve alopecia X in an intact male
castration
What are some other names for Alopecia X
-Adrenal Sex Hormone imbalance
-Maturity onset growth hormone responseive dermatosis
-Estrogen, testosterone responsive dermatosis
-Castration responsive dermatosis
-Pseudo-Cushings disease
What breeds are associated with Alopecia X
nordic breeds most common: pomeranian, chow chow, samoyed, keeshond, siberian husky, malamute, norweigan elkhound, finish spitz, american eskimo
miniature poodle
What kind of dogs are alopecia X common in
Intact males
young dogs- 2.5 yrs at onset
northern breeds, mini poodle
Alopecia X causes
hair cycle arrest
What is Telogen Effluvium
acute widespread alopecia from telogen defluxion
severe illness/metabolic stress (fever, pregnancy, lactation, shock, drugs) cause hairs to go into telogen stage
hair loss starting 3-4 weeks or more (1-3 months) after incident as new hairs regrowing
What causes telogen effluvium
severe illness/metabolic stress (fever, pregnancy, lactation, shock, drugs) cause hairs to go into telogen stage
hair loss starting 3-4 weeks or more (1-3 months) after incident as new hairs regrowing
Post-Clipping alopecia
follicular arrest in dogs with history of clipping, surgically scrubbed +/- epidural
no hair regrowth, unknown etiology
rest of the coat/skin is normal
regrowth in 6-24 months (usually <1 year)
melatonin? thyroid hormone?
try low level laser 2x weekly for 2 month
canine flank alopecia is common in what species
Airedales, Boxers, Schnauzers, Bulldogs
What is seen with canine flank alopecia
alopecia restricted to the flank of boxers, bulldogs, schnauzers, airedales
hyperpigmentation
may be seasonally cyclic
may involve melatonin deficiency
normal dogs- decreased photoperiod, increased melationin to stimulate winter pelage
What may cause canine flank alopecia seen in boxers and schnauzers and bulldogs and airedales
may involve melatonin deficiency
normal dogs- decreased photoperiod, increased melationin to stimulate winter pelage
may be able to resolve with melatonin supplementation
How do you treat the follicular dysplasia seen with canine flank alopecia
often responds to melatonin therapy
50-75% respond
melatonin implant with 4-6 month release
low level laser- twice weekly for 2 months
blue, fawn color coat seen in doberman, great dane, whippet where alopecia is restricted to the dilute area of the coat
Starts 6-12 months to 2-3 years
Color Dilution Alopecia (follicular dysplasia)
When does color dilution alopecia typically present
younger dogs
Starts 6-12 months to 2-3 years
What do you see diagnostically with color dilution alopecia
hairs with macromelanosomes that weaken the hair shafts
biopsies: pigment coloring around hair follicle
What breeds do you see acquired pattern alopecia (pattern baldness) in
Dachshund, boston terrier, chihuahua, whippet
Acquired Pattern Alopecia (pattern baldness)
Alopecia that develops as young dogs (1-3 years)
occurs in dachshund, boston terrier, chihuahua, whippet
may respond to melatonin therapy
photobiomodulation?
No need to treat (cosmetic)
What breeds typically get caudal thigh alopecia
greyhounds
