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Dermatology > Non-inflammatory Alopecic diseases > Flashcards

Non-inflammatory Alopecic diseases Flashcards

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1
Q

Causes of alopecia

A
  • Traumatic (Allergies, parasites, pruritic pyoderma, Malassezia)
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2
Q

What re causes of hair falling out from folliculitis?

A
  • Pyoderma
  • Demodex
  • Dermatophytosis
  • Also sebaceous adeniti
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3
Q

Non-inflammatory causes of alopecia from hair cycle arrest

A
  • Endocrine
  • Alopecia X
  • Cyclic flank alopecia
  • Pattern alopecia
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4
Q

Non-inflammatory causes of alopecia from dystrophies/dysplasias?

A
  • Congenital hypotrichosis
  • Color dilution alopecia
  • Black hair follicular dysplasia
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5
Q

Benefits of hair

A
  • Thermal insulation/regulation
  • SEnsory perception
  • Barrier protection
  • Camouflage
  • Social communication
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6
Q

What is primary hair?

A
  • Undercoat or guard
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7
Q

What are secondary hairs?

A
  • Undercoat
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8
Q

Do cats have more primary or secondary hairs?

A
  • More secondary hairs, which is why they are softer
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9
Q

Do puppies lose their undercoats?

A
  • No, they gain adult coats
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10
Q

What are the three phases of the hair cycle?

A
  1. Anagen
  2. Catagen
  3. Telogen phase
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11
Q

Anagen phase - what’s happening?

A
  • Active growth

- Producing new cells and keratin

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12
Q

Catagen phase - what’s happening?

A
  • Stops growing

- Detaches slowly

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13
Q

Telogen phase - what’s happening?

A
  • Resting phase

- Prepares the next cycle

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14
Q

What controls the hair cycle (and what is most important?)

A
  • Photoperiod (very important)**
  • Ambient temperature
  • Nutrition
  • Genetics
  • Hormones
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15
Q

When is activity and hair growth maximal or minimal?

A
  • Maximal in summer

- Minimal in winter

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16
Q

What causes increased shedding?

A
  • Increased with artifical light
  • Telogen hairs
  • Disease states
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17
Q

What type of cycles do most humans poodles have?

A
  • Anagen cycles
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18
Q

WHat type of hair cycles do most dogs have?

A
  • Telogen cycles
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19
Q

Is telogen a pathologic state?

A
  • No
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20
Q

Are telogen hairs easy to pull out?

A
  • Not necessarily
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21
Q

What hormone accelerates anagen hairs?

A
  • Thyroid hormones or growth hormone
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22
Q

What hormones inhibit anagen?

A
  • Glucocorticoids/estrogens

- Suppress hair growth rate

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23
Q

How long does hair take to regrow on a short coated dog?

A
  • 3-4 months
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24
Q

How long does hair take to fully regrow on a long-coated dog?

A
  • UP to 18 months
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25
What are alopecic breeds?
- Chinese crested - Xoloitzcuintle - Sphinx cat
26
Congenital hypotrichosis - what causes?
- Not well understood
27
Congenital hypotrichosis - by what point do they lose their hair?
- Either brn with no hair or lose hair within the first month -
28
Breeds with congenital hypotrichosis
- Chihuahua, poodles, GSD
29
How to differentiate congenital hypotrichosis
- Look for signs of active inflammation
30
Color dilution alopecia - what causes
- ALopecia associated with coat color dilution gene
31
What color hair coats associated with color dilution alopecia?
- Blue or fawn colored hair coats
32
Breeds associated with color dilution alopecia
- Dobermans - Great Danes - Dachshunds - Italian Greyhounds
33
When do clinical signs start with color dilution alopecia?
- 6 months to three years
34
Clinical signs associated with color dilution alopecia, and where do they show up?
- Alopecia - Seborrhea - Pyoderma (papules, pustlues, crusts, epidermal collarettes) - With the trunk most severe
35
What underlying causes of pyoderma should you look for even with color dilution allopecia?
- Allergy or endocrine
36
Diagnosis of color dilution alopecia
- Microscopic examination of the hair r(trichogram) reveals melanin clumping resulting in distortion of the hair shaft - Histopath reveals abnormal melanin clumping within the hair shaft and periadnexally
37
Treatment for color dilution alopecia
- Symptomatic therapy for seborrhea and antibiotics for pyoderma - Melatonin may possibly help stimulate hair growth but mechanism unknown
38
How common is black hair follicular dysplasia?
- Uncommon
39
Age of dog with black hair follicular dysplasia?
- Young dogs | - Often born normal but show changes within 4 weeks
40
WHere are the lesions with black hair follicular dysplasia?
- Only black hairs affected
41
Histopathology for black hair follicular dysplasia?
- Same as with color dilution alopecia | - Abnormal melanin clumping within the hair shaft and periadnexally
42
Trichogram for black hair follicular dysplasia?
- Not helpful because the hairs are too dark (black)
43
What is the major problem with most hair cycle abnormalities?
- Hairs remain in telogen and fail to enter anagen
44
Factors that influence hair cycle
- genetics - Trauma - Intrinsic factors (growth factors) - Extrinsic factors (endocrine, immunologic, metabolic)
45
Diseases associated with hair cycle abnormalities
- Endocrine dermatoses (hypothyroidism, Cushing's) - Alopecia X - Cyclic flank alopecia - Pattern alopecia/baldness - Anagen/telogen defluxion - Post clipping alopecia
46
Clinical signs associated with hair cycle abnormalities ? Are any of these specific for hair cycle abnormalities?
- ALopecia (bilateral and symmetrical) - Dull, dry, brittle hairs - Failure to regrow hair - Increased pigmentation - Seborrhea - Comedomes - SEcondary infections (yeast, pyoderma) - Nonpruritic usually unless pyoderma, seborrhea, or yeast dermatitis present
47
Histological characteristics
- Hyperkeratotis (epidermal, follicular) - Epidermal hyperkeratosis clinically seen as seborrhea - Follicular hyperkeratotis clinically seen as comedoems - Follicular dilation (filld with keratin) - Follicular atrophy - Telogen hairs - Epidermal melanosis - Epidermal atrophy (more common for Cushing's)
48
Are biopsy findings with hair cycle disorders specific?
- No, they cannot differentiate endocrine diseases from other causes of non-inflammatory alopecias
49
HPA axis
- Hypothalmus releases thyrotropin releasing hormone - TRH on pituitary causes release of Thyroid stimulating hormoen (TSH) - TSH on thyroid gland causes release of T4, T3, and RT3 - Negative feedback possible with TSH on hypothalamus and the thyroid hormones on both the pituitary and hypothalamus
50
Where do primary, secondary, and tertiary hypothyroidism affect the animal? Which is most common?
- Primary (most common - thyroid gland) - SEcondary (pituitary gland) - Tertiary (hypothalamus)
51
What is primary hypothyroidism?
- Lack of functional thyroid tissue | - Most common form >95%
52
What is most common cause of primary hypothyroidism?
- Acquired - Lymphocytic thyroiditis ~50% - Idiopathic follicular atrophy - Least likely to be secondary neoplasia
53
Iatrogenic causes of primary hypothyroidism
- Surgery - Radioactive iodine therapy - Anti-thyroid medications
54
How common is congenital primary hypothyroidism?
- Rare
55
Cretinism
- Thyroid gland agenesis or dysgensis - Dyshormonogenesis (thyroid peroxidase deficiency) - Deficient dietary iodine - Ingestion of goitrogens
56
Why don't you see congenital primary hypothyroid ism that often?
- Early death so may go undiagnosed | - Disporportionate dwarfism
57
Secondary hypothyroidism
- Imparied secretion of TSH from the pituitary gland
58
Acquired causes of 2° hypothyroidism
- Neoplasia - Illness, malnutrition - Pituitary suppression, e.g. glucocorticoid administration
59
Congenital causes of 2° hypothyroidism
- Cystic Rathke's pouch | - Other pituitary hormone deficiencies, e.g. ADH
60
Tertiary hypothyroidism
- Lack of TRH in the hypothalamic supraoptic and paraventricular nuclei - Never documented in the dog
61
Signalment of hypothyroidism
- RARE under one year - Peak incidence around 4-6 years - No sex predisposition - Dobies, Golden and Labrador Retrievers, Dachshunds, Cocker Spaniels
62
Clinical signs of hypothyroidism
- Vague, diffuse, gradual onset - Not pathognomonic for the disease - Most common is dermatologic and metabolic - General appearance: dullness, lethargy, exercise intolerance, obesity without history of polyphagia, cold intolerance ("heat seekers"_
63
Dermatologic signs with hypothyroidism
- >85% of dogs - Dry skin and hair coat (seborrhea) - Alopecia in areas of wear/pressure points - Rat tail or bridge of nose - Bilateral symmetrical alopecia - Dull, dry, brittle hair (retained in telogen phase) - Lose primary hairs and retain guard hairs - Failure to regrow hair after clipping - Hyperpigmentation in alopecic areas - Seborrhea, lichenification, comedones - Generally non-pruritic - Myxedema - REcurrent infections
64
Why do dogs with hypothyroid have wear of their hair?
- Thyroid hormones needed for initiation of anagen phase
65
What is myxedema?
- Severe cases - Excess mucopolysaccharides (+hyaluronic acid in dermis) - Results in tragic facial expression (more advanced often)
66
Recurrent infections with hypothyroidism
- Otitis externa - Pyoderma - Effect on immune system - Effect on barrier function - may be their only sign
67
Other clinical signs with hypothyroidism
- Cardiovascular effects - Ocular abnormalities (rare) - Neurologic abnormalities (from segmental demyelinization) - GI abnormalities - REproductive abnormalities - Myxedema coma
68
Diagnostic tests for hypothyroidism
- No single test (rarely confirm with biopsy) - Evaluate all data (signalment, history, clinical signs, physical exam, clinicopathologic data, thyroid ohrmone concentrations; reponse to thyroid supplementation) - Hypothyroidism tends to be overdiagnosed - T4, free T4, TSH measurements
69
Which drugs alter thyroid hormones?
- Glucocorticoids | - TMS antibiotics
70
How do glucocorticoids affect thyroid hormones?
- Decrease TT4, free T4 - Decrease T4 to T3 conversion - Decrease TSH - Could cause a false positive I think
71
How do trimethoprim-sulfa antibiotics alter thyroid hormones?
- Inhibits iodine conversion - Decrease TT4, decrease free T4, and increase TSH - True but reversible hypothyroidism
72
Diagnosis of hypothyroidism
1. Compatible clinical signs 2. Low to low normal TT4 3. Low free T4 4. Elevated TSH with low T4, low free T4 5. Response to therapeutic trial
73
Medication for treatment of hypothyroidism
- L-thyroxine
74
HPA axis for cortisol
- Hypothalamus stimulates corticotropin releasing hormoen onto pituitary gland - Pituitary gland releases ACTH onto the adrenal glands - Adrenal glands release cortisol, which has a negative effect on the pituitary and CRH
75
Appearance of adrenal glands with pituitary dependent hyperadrenocorticism
- With pituitary dependent it produces a lot of ACTH and causes hypertrophy of the adrenal glands
76
Appearance of adrenal glands with adrenal dependent hyperadrenocorticisim
- One is overproducing cortisol, which then goes back and has negative feedback on the hypothalamus and pituitary gland - This results in atrophy of the unaffected adrenal gland
77
What are the five P's of hyperadrenocorticism?
- Polyuria - Polydipsia (interference with release and action of ADH) - Polyphagia (direct effect of glucocorticoids) - Pot belly (intraabdominal fat, hepatomegaly, full urinary bladder, lax abdominal muscles) - Panting or tachypnea
78
Causes of panting with Cushing's
- THoracic fat - Abdominal distention - Muscular weakness - Thromboembolic complicatiosn - Many small breed dogs also have mitral insufficiency, collapsing trachea, etc.
79
Appearance of alopecia with Cushing's
- Bilateral, symmetric - Often spares head and extremities - Atrophy of hair follicles - Nonpruritic - May fail to regrow their hair - Hyperpigmentation
80
Common age of dogs with Cushing's
- Middle to older dogs
81
Common breeds for hyperadrenocorticism
- Bostons, Dachshunds, Boxers, Shih tzus
82
Dermatologic signs with Cushing's
- Bilateral symmetrical alopecia sparing head and distal extremities - Dermal atrophy (thin epidermis and dermis) - Recurring pyodermas** - Demodicosis - Milia - Calcinosis cutis - Poor wound healing - Bruising or petechia from minmimal trauma due to blood vessel fragility
83
What may be the only sign associated with Cushing's?
- Recurrent pyodermas
84
What are the 5 P's?
- Polydipsia - Polyuria - Polyphagia - Panting - Pendulous abdomen
85
Other clinical signs associated with Cushing's
- Urinary tract infections - Muscle atrophy - Generalized weakness
86
More serious complications with Cushing's
- PTE - Cerebral infarct - Glomerulonephritis - Hypertension - Opportunistic infections - Diabetes mellitus - Acute pancreatitis - Pyelonephritis - Pituitary macroadenomas
87
What should you immediately think with dermal atrophy or milia?
- You really should be thinking steroids
88
Comedomes
- Keratin plugged follicles
89
Signs associated with pyoderma
- Papules - Pustules - Crusts - Epidermal collarettes - patchy alopecia - +/- Pruritus
90
Diagnosis of Cushing's
- History - Clinical signs - Minimum data base (CBC/Chem/UA
91
CBC signs with Cushing's
- Lymphopenia and eosinopenia | - Monocytosis and neutrophilia
92
Chemistry changes with Cushing's
- ALP elevated (85-95%) - Mildly elevated ALT - Cholesterol
93
UA changes with Cushing's
- Dilute
94
Screening tests for Cushing's
- ACTH Stimulation test - Low dose dexamethasone suppression test - Urine cortisol to creatinine
95
Differentiating tests
- Sometimes LDDST - HDDST - Endogenous ACTH - Advanced imaging (AUS/CT/MRI)
96
Treatment of HAC
- Trilostane (not benign; need to make sure diagnosis is correct) - Lysodren
97
Who gets Alopecia X?
- Pomeranians - Poodles - Nordic breeds
98
Age of dogs with alopecia X?
- 1-10 years of age
99
Sex of dogs with Alopecia X?
- Males and females equally
100
Clinical signs of Alopecia X?
- Symmetrical alopecia sparing head and extremities** - Loss of guard hairs progressing to complete alopecia of the neck, tail, rump, perineum, caudal thighs**, and ultimately trunk** - No systemic illness - Diffuse hyperpigmentation (owners breeders falsely refer to it as Black Skin Disease)
101
Pathomechanism of Alopecia X?
- Unknown | - Defect of anagen hair cycle?
102
Diagnosis of Alopecia X?
- Rule out other causes of endocrine alopecias - Hypothyroidism and Cushing's - +/- biopsy to rule out sebaceous adenitis
103
Treatment possibilities for Alopecia X?
- Melatonin (most benign treatment; up to 40% may regrow hair); may take 3-4 months - Neutering of intact dogs (castration responsive dermatosis)
104
Treatments NOT recommended for Alopecia X?
- Trilostane (not without potential for side effects) - Lysodren (high potential for side effects) - Growth hormone (can cause diabetes) - Progesterone - Testosterone (high potential for side effects)
105
WHen does pattern alopecia typically start?
<1 year of age
106
Progression of pattern alopecia/
- Typically born with normal hair coat then develops alopecia
107
What are the four syndromes of pattern alopecia?
1. Pinnal alopecia of dachshunds 2. Ventral and caudal alopecia of Dachshunds and Boston Terriers (no inflammation, excoriations, pustules, papules, crusts) 3. Pattern alopecia of Portugese water dogs and American water spaniels (could be an allergy, so look at the skin) 4. Bald thigh syndrome of greyhounds
108
When does cyclic flank alopecia tend to occur?
- Develops during periods of short day length (fall/winter/spring)
109
What can resolve cyclic flank alopecia? Is it always effectie?
- UV light exposure | - Not always
110
Breed predispositions for cyclic flank alopecia
- Airedales - Boxers - English Bulldogs - Can be hyperpigmented - Serpiginous (all over)
111
Diagnosis of cyclic flank alopecia
- Consider/rule out endocrine causes - Hypothyroidism - Cushing's disease - Skin biopsy shows follicular keratosis; deformed follicles that are unusual telogen follicles described by pathologists
112
Where is cyclic flank alopecia most often seen/
- PNW and northern parts of the US
113
Age of dogs with seasonal trunk alopecia or cyclic flank alopecia?
- 1.5-4.5 years
114
What is "witches foot"?
- Deformed telogen follicles described by pathologists
115
Treatment for cyclic trunk alopecia
- Melatonin may shorten duration and prevent recurrence - Increase UV sunlight - Benign neglect
116
Biopsy of pattern alopecia/baldness
- Small miniature sized follicles and adnexa - Small anagen hairs - Not always definitive
117
Treatment for pattern alopecia/baldness
- Melatonin? | - Benign neglect
118
Excessive shedding - when is normal shed cycle?
- spring and fall
119
In normal shedding, what should not be created with epilation?
- Alopecic area
120
What can cause more shedding?
- Hyperexcitable or nervous animals
121
What should you check for if there has been a change in shedding?
- Endocrinopathies
122
What to do for excessive shedding
- Remove the dead hairs, diet changes, increased free fatty aids, adjust light and/or temperature

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