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Dermatology > Non-Inflammatory Alopecia > Flashcards

Non-Inflammatory Alopecia Flashcards

1
Q

Causes of Alopecia

A

Allergies
Parasites
Pruritic pyderma
Malassezia

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2
Q

Alopecia

Hair falling out suggests (see divots)

A

Folliculitis:
Pyoderma
Demodex
Dermatophytosis (erythematous)

Sebaceous adenitis

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3
Q

Alopecia

Non-inflammatory causes

A 
Hair cycle arrest:
Endocrine (bilateral, symmetrical) - hypothyroidism
Alopecia X (Poms)
Cyclic flank alopecia
Pattern alopecia
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4
Q

Dystrophies/Dysplasias

Background

A

Non-inflammatory cause of alopecia

Congenital hypotrichosis
Color dilution alopecia
Black hair follicular dysplasia

Can get secondary pyoderma

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5
Q

Hair Cycle

A

Anagen Phase: active growth; producing new cells and keratin

Catagen Phase: stops growing; detaches slowly

Telogen Phase: resting phase; prepares next cycle

Starts over

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6
Q

Hair Cycle and Haircoat controlled by:

A 
Photoperiod!
Ambient temp
Nutrition
Genetics
Hormones
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7
Q

Hair Cycle and Haircoat

Photoperiod

A

Activity and hair growth is maximal in summer and minimal in winter

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8
Q

Hair Cycle and Haircoat

Shedding

A

Increased with artificial light
Telogen hairs
Disease states

Help shed by grooming

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9
Q

Hair Cycle and Haircoat

Telogen vs. Anagen

A

Most humans and poodles have anagen cycles (constantly growing hair)

Most dogs have telogen cycles; not necessarily easy to pull out

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10
Q

Hair Cycle and Haircoat

Thyroid Hormones/Growth Hormones

A

Accelerates anagen hairs (increases growth)

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11
Q

Hair Cycle and Haircoat

Glucocorticoids/Estrogens

A

Inhibits anagen (stuck in telogen phase; not growing)

Suppress hair growth rate

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12
Q

Hair Cycle and Haircoat

Regrowth

A

Short coated dog:
3-4 months

Long coated dog:
Up to 18 months

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13
Q

Congenital hypotrichosis

A

Not well understood

Born with no hair or lose hair within first month

Chihuahua, poodles, GSD

Non-inflammatory!
Note: if there is inflammation most likely demodex not this condition

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14
Q

Color dilution alopecia
What is it?
Breeds

A

Alopecia associated with coat color dilution gene

Blue or fawn colored hair coats

Breeds:
Dobermans
Great Danes
Dachshunds
Italian Greyhounds
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15
Q

Color dilution alopecia

Clinical Signs

A

Alopecia: 6 months to 3 years of age

Bacterial folliculitis (pyoderma)

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16
Q

Top 3 DfDx for Folliculitis!

A

Pyoderma
Demodex
Ring worm

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17
Q

Color dilution alopecia

Diagnosis

A

Signalment

Microscopic examination of hairs = melanin clumping

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18
Q

Non-specific clinical signs with hair cycle abnormalities

A 
Alopecia
Dull, dry, brittle hairs
Failure to regrow hair
Increased pigmentation
Seborrhea
Comedones
Secondary infections
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19
Q

Primary hypothyroidism

Background

A

Lack of functional thyroid tissue

Most common form >95%

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20
Q

Primary hypothyroidism

Acquired

A

Most common form

Lymphocytic thyroiditis
Idiopathic follicular atrophy
Secondary to neoplasia (least likely)

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21
Q

Primary hypothyroidism

Iatrogenic

A

Surgery
Radioactive iodine
Anti-thyroid medications

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22
Q

Disease associated with hair cycle abnormalities

A 
Endocrine dermatoses(hypothyroidism, Cushing's)
Alopecia X
Cyclic flank alopecia
Pattern alopecia/baldness
Anagen/telogen defluxion
Post clipping alopecia
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23
Q

Hair cycle disorders

Histology

A

Histopathology cannot differentiate between endocrine and other non-inflammatory alopecias

Epidermal hyperkeratosis: seborrhea
Follicular hyperkeratosis: comedones
Follicular dilation: dilated because full of keratin
Follicular atrophy: small follicles and adnexal units
Telogen hairs
Epidermal meanosis
Epidermal atrophy

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24
Q

Congenital primary hypothyroidism

A

Rare

Dwarf puppy

Thyroid gland agenesis or dysgenesis
Deficient dietary iodine
Ingestion of goitrogens

Early death; may go undiagnosed

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25
Secondary hypothyroidism
Impaired secretion of TSH from the pituitary Uncommon
26
Secondary hypothyroidism | Acquired
Neoplasia Illness Malnutrition Pituitary suppression (administration of glucocorticoids)
27
Secondary hypothyroidism | Congenital
Very rare Cystic Rathke's pouch Pituitary hormone deficiencies (ADH)
28
Hypothyroidism Signalment
``` Dobermans Dachshund Labrador Poodle Cocker Spaniel Goldens ``` 4-6 years of age (peak)
29
Hypothyroidism Clinical Signs
Vague, diffuse, gradual onset Most common: dermatologic and metabolic
30
Hypothyroidism | General Appearance
``` Dullness Lethargy Exercise intolerance Obesity without history of polyphagia Cold intolerance (heat seekers) ```
31
Hypothyroidism Dermatologic Signs | Major sign
Alopecia Dry skin and haircoat Thyroid hormones needed for initiation of anagen Areas of wear/pressure points (rat tail) Bilateral symmetrical alopecia Generally non-pruritic (unless secondary pyoderma) Hyperpigmentation
32
Hypothyroidism | Dermatologic Signs
>85% of dogs have derm signs Puppy coat; loose primary hairs, retain guard hairs Dull, dry, brittle hair (retained in telogen phase) Failure to regrow hair after clipping (no anagen phase) Seborrhea Lichenification Comedomes (keratin plugged follicles) Hyperpigmentation
33
Hypothyroidism Dermatologic Signs Myxedema
Severe cases only Excess mucopolysaccharides + hyaluronic acid in dermis Causes "tragic facial expression"
34
Hypothyroidism | Secondary infections
Otitis externa Pyoderma Hypothyrodism causes defects in immune system such as decrease in barrier function
35
Hypothyroidism | Diagnostics
Evaluate all data! Often overdiagnosed Signalment, history, clinical signs, PE Clinicopathologic data Thyroid hormone concentrations Response to thyroid supplementation
36
Drugs which alter thyroid hormones (KNOW)
Glucocorticoids: Decrease TT4 and free T4 Decrease T4 conversion to T3 Decrease TSH ``` TMS antibiotics: Inhibits iodine conversion Decrease TT4, free T4 Increases TSH Results in true but reversible hypothyroid state ```
37
Hypothyroidism | Specific Diagnostic Tests
Low to low-normal TT4 Low Free T4 Elevated TSH with low T4, low free T4 Response to therapeutic trial
38
Pituitary Dependent Hyperardrenocorticism | What happens
Pituitary produces a lot of ACTH Creates large adrenal glands (overstimulated); a lot of cortisol produced
39
Adrenal Dependent Hyperadrenocorticism | What happens
One adrenal gland goes rogue and produces a lot of cortisol Negative feedback to pituitary gland so no longer producing ACTH Ipsilateral adrenal gland will regress (not getting stimulated by ACTH anymore)
40
Hyperadrenocorticism is...
Cushing's
41
Hyperadrenocorticism | The 5 Ps
PU/PD Polyphagia Panting (tachypnea) Pot belly Not pruritic; thought that increased cortisol decreases this sensation
42
Hyperadrenocorticism | Why PU/PD?
Interference with release and action of ADH
43
Hyperadrenocorticism | Why polyphagia?
Direct effect of glucocorticoids
44
Hyperadrenocorticism | Why panting?
Thoracic fat Abdominal distension Muscular weakness Thromboembolic complications
45
Hyperadrenocorticism | Why abdominal enlargement?
Intraabominal fat Hepatomegaly Full urinary bladder Lax abdominal muscles
46
Hyperadrenocorticism | Alopecia
Bilateral, symmetric (spares head and extremities) Atrophy of hair follicles Non-pruritic (unless secondary pyoderma)
47
Hyperadrenocorticism What happens to the skin? KNOW
Thinning Dermal atrophy! Milia; white spots (look like zits)
48
See Comedones think...
Demodex | Cushing's
49
Hyperadrenocorticism | Superficial bacterial pyoderma
Will get recurring pyoderma ``` Papules Pustules Crust Epidermal collarettes Patchy alopecia +/- Pruritus ``` Mainly on ventral abdomen
50
Hyperadrenocorticism | Diagnosis
History, Clinical Signs CBC: stress leukogram (segments, monocytosis, leukopenia) Chem: Increased ALP, ALT, cholesterol UA: dilute
51
Hyperadrenocorticism | Screening Tests
ACTH Stim LDDS Test Urine cortisol:creatinine
52
Hyperadrenocorticism | Differentiating tests
``` LDDS Test (sometimes) HDDST ``` Endogenous ACTH Advanced imaging: CT, MRI
53
Hyperadrenocorticism | Treatment
Diagnose before treatment or can be dangerous Trilostane Lysodren
54
Alopecia X | Signalment
Commonly seen in plush coated breeds: Poms Poodles Nordic breeds (Skiperkee) Age: 1-10 years
55
Alopecia X | Clinical Signs
Symmetrical alopecia sparing head and legs Diffuse hyperpigmentation NOT an infection
56
Alopecia X | Pathophysiology
Unknown Defect in anagen hair cycle most likely
57
Alopecia X | Diagnosis
Diagnosis of exclusion Rule out other causes of endocrine alopecias: Hypothyroidism Cushing's +/- biopsy to rule out sebaceous adenititis
58
Alopecia X | Treatment
Melatonin: 40% of dogs will grow hair back in 3-4 months Neutering intact dogs No cure
59
Alopecia X | Treatments NOT recommended
Hyperadrenocorticism Rx: Trilostane and Lysodren Growth hormones Progesterone Testosterone
60
Pattern Alopecia | 4 Syndromes
1. Pinnal alopecia of Dachshunds 2. Ventral and caudal alopecia of Dachshunds and Boston Terriers 3. Pattern alopecia of Portugese water dogs and American water spaniels 4. Bald thigh syndrome of greyhounds
61
Cyclic Flank Alopecia | What is it?
Seasonal truncal alopecia; during periods of short day length Resolves with UV exposure Common in PNW Diagnosis of exclusion
62
Cyclic Flank Alopecia | Breeds
Airdales Boxers English Bulldogs
63
Dogs with allergies generally do what?
Itch!
64
Doges with non-inflammatory alopecia disorders do not do what?
Itch!

Dermatology (13 decks)

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