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Dermatology > Non-Inflammatory Alopecia > Flashcards

Non-Inflammatory Alopecia Flashcards

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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
Q

Secondary hypothyroidism

A

Impaired secretion of TSH from the pituitary

Uncommon

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26
Q

Secondary hypothyroidism

Acquired

A

Neoplasia
Illness
Malnutrition
Pituitary suppression (administration of glucocorticoids)

27
Q

Secondary hypothyroidism

Congenital

A

Very rare

Cystic Rathke’s pouch
Pituitary hormone deficiencies (ADH)

28
Q

Hypothyroidism Signalment

A 
Dobermans
Dachshund 
Labrador
Poodle
Cocker Spaniel
Goldens

4-6 years of age (peak)

29
Q

Hypothyroidism Clinical Signs

A

Vague, diffuse, gradual onset

Most common: dermatologic and metabolic

30
Q

Hypothyroidism

General Appearance

A 
Dullness
Lethargy
Exercise intolerance
Obesity without history of polyphagia 
Cold intolerance (heat seekers)
31
Q

Hypothyroidism Dermatologic Signs

Major sign

A

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
Q

Hypothyroidism

Dermatologic Signs

A

> 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
Q

Hypothyroidism
Dermatologic Signs
Myxedema

A

Severe cases only

Excess mucopolysaccharides + hyaluronic acid in dermis

Causes “tragic facial expression”

34
Q

Hypothyroidism

Secondary infections

A

Otitis externa
Pyoderma

Hypothyrodism causes defects in immune system such as decrease in barrier function

35
Q

Hypothyroidism

Diagnostics

A

Evaluate all data! Often overdiagnosed

Signalment, history, clinical signs, PE

Clinicopathologic data

Thyroid hormone concentrations

Response to thyroid supplementation

36
Q

Drugs which alter thyroid hormones (KNOW)

A

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
Q

Hypothyroidism

Specific Diagnostic Tests

A

Low to low-normal TT4
Low Free T4
Elevated TSH with low T4, low free T4
Response to therapeutic trial

38
Q

Pituitary Dependent Hyperardrenocorticism

What happens

A

Pituitary produces a lot of ACTH

Creates large adrenal glands (overstimulated); a lot of cortisol produced

39
Q

Adrenal Dependent Hyperadrenocorticism

What happens

A

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
Q

Hyperadrenocorticism is…

A

Cushing’s

41
Q

Hyperadrenocorticism

The 5 Ps

A

PU/PD
Polyphagia
Panting (tachypnea)
Pot belly

Not pruritic; thought that increased cortisol decreases this sensation

42
Q

Hyperadrenocorticism

Why PU/PD?

A

Interference with release and action of ADH

43
Q

Hyperadrenocorticism

Why polyphagia?

A

Direct effect of glucocorticoids

44
Q

Hyperadrenocorticism

Why panting?

A

Thoracic fat
Abdominal distension
Muscular weakness
Thromboembolic complications

45
Q

Hyperadrenocorticism

Why abdominal enlargement?

A

Intraabominal fat
Hepatomegaly
Full urinary bladder
Lax abdominal muscles

46
Q

Hyperadrenocorticism

Alopecia

A

Bilateral, symmetric (spares head and extremities)

Atrophy of hair follicles

Non-pruritic (unless secondary pyoderma)

47
Q

Hyperadrenocorticism
What happens to the skin?
KNOW

A

Thinning
Dermal atrophy!

Milia; white spots (look like zits)

48
Q

See Comedones think…

A

Demodex

Cushing’s

49
Q

Hyperadrenocorticism

Superficial bacterial pyoderma

A

Will get recurring pyoderma

Papules
Pustules
Crust
Epidermal collarettes
Patchy alopecia
\+/- Pruritus

Mainly on ventral abdomen

50
Q

Hyperadrenocorticism

Diagnosis

A

History, Clinical Signs

CBC: stress leukogram (segments, monocytosis, leukopenia)
Chem:
Increased ALP, ALT, cholesterol

UA: dilute

51
Q

Hyperadrenocorticism

Screening Tests

A

ACTH Stim
LDDS Test

Urine cortisol:creatinine

52
Q

Hyperadrenocorticism

Differentiating tests

A 
LDDS Test (sometimes)
HDDST

Endogenous ACTH
Advanced imaging:
CT, MRI

53
Q

Hyperadrenocorticism

Treatment

A

Diagnose before treatment or can be dangerous

Trilostane
Lysodren

54
Q

Alopecia X

Signalment

A

Commonly seen in plush coated breeds:
Poms
Poodles
Nordic breeds (Skiperkee)

Age: 1-10 years

55
Q

Alopecia X

Clinical Signs

A

Symmetrical alopecia sparing head and legs

Diffuse hyperpigmentation

NOT an infection

56
Q

Alopecia X

Pathophysiology

A

Unknown

Defect in anagen hair cycle most likely

57
Q

Alopecia X

Diagnosis

A

Diagnosis of exclusion

Rule out other causes of endocrine alopecias:
Hypothyroidism
Cushing’s
+/- biopsy to rule out sebaceous adenititis

58
Q

Alopecia X

Treatment

A

Melatonin: 40% of dogs will grow hair back in 3-4 months

Neutering intact dogs

No cure

59
Q

Alopecia X

Treatments NOT recommended

A

Hyperadrenocorticism Rx: Trilostane and Lysodren

Growth hormones
Progesterone
Testosterone

60
Q

Pattern Alopecia

4 Syndromes

A
  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
Q

Cyclic Flank Alopecia

What is it?

A

Seasonal truncal alopecia; during periods of short day length

Resolves with UV exposure

Common in PNW

Diagnosis of exclusion

62
Q

Cyclic Flank Alopecia

Breeds

A

Airdales
Boxers
English Bulldogs

63
Q

Dogs with allergies generally do what?

A

Itch!

64
Q

Doges with non-inflammatory alopecia disorders do not do what?

A

Itch!

Dermatology (13 decks)

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