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Dermatology > Non-inflammatory Alopecic diseases > Flashcards

Non-inflammatory Alopecic diseases Flashcards

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
Q

What are alopecic breeds?

A
  • Chinese crested
  • Xoloitzcuintle
  • Sphinx cat
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26
Q

Congenital hypotrichosis - what causes?

A
  • Not well understood
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27
Q

Congenital hypotrichosis - by what point do they lose their hair?

A
  • Either brn with no hair or lose hair within the first month

-

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28
Q

Breeds with congenital hypotrichosis

A
  • Chihuahua, poodles, GSD
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29
Q

How to differentiate congenital hypotrichosis

A
  • Look for signs of active inflammation
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30
Q

Color dilution alopecia - what causes

A
  • ALopecia associated with coat color dilution gene
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31
Q

What color hair coats associated with color dilution alopecia?

A
  • Blue or fawn colored hair coats
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32
Q

Breeds associated with color dilution alopecia

A
  • Dobermans
  • Great Danes
  • Dachshunds
  • Italian Greyhounds
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33
Q

When do clinical signs start with color dilution alopecia?

A
  • 6 months to three years
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34
Q

Clinical signs associated with color dilution alopecia, and where do they show up?

A
  • Alopecia
  • Seborrhea
  • Pyoderma (papules, pustlues, crusts, epidermal collarettes)
  • With the trunk most severe
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35
Q

What underlying causes of pyoderma should you look for even with color dilution allopecia?

A
  • Allergy or endocrine
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36
Q

Diagnosis of color dilution alopecia

A
  • 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
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37
Q

Treatment for color dilution alopecia

A
  • Symptomatic therapy for seborrhea and antibiotics for pyoderma
  • Melatonin may possibly help stimulate hair growth but mechanism unknown
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38
Q

How common is black hair follicular dysplasia?

A
  • Uncommon
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39
Q

Age of dog with black hair follicular dysplasia?

A
  • Young dogs

- Often born normal but show changes within 4 weeks

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40
Q

WHere are the lesions with black hair follicular dysplasia?

A
  • Only black hairs affected
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41
Q

Histopathology for black hair follicular dysplasia?

A
  • Same as with color dilution alopecia

- Abnormal melanin clumping within the hair shaft and periadnexally

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42
Q

Trichogram for black hair follicular dysplasia?

A
  • Not helpful because the hairs are too dark (black)
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43
Q

What is the major problem with most hair cycle abnormalities?

A
  • Hairs remain in telogen and fail to enter anagen
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44
Q

Factors that influence hair cycle

A
  • genetics
  • Trauma
  • Intrinsic factors (growth factors)
  • Extrinsic factors (endocrine, immunologic, metabolic)
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45
Q

Diseases 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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46
Q

Clinical signs associated with hair cycle abnormalities ? Are any of these specific for hair cycle abnormalities?

A
  • 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
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47
Q

Histological characteristics

A
  • 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)
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48
Q

Are biopsy findings with hair cycle disorders specific?

A
  • No, they cannot differentiate endocrine diseases from other causes of non-inflammatory alopecias
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49
Q

HPA axis

A
  • 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
Q

Where do primary, secondary, and tertiary hypothyroidism affect the animal?

Which is most common?

A
  • Primary (most common - thyroid gland)
  • SEcondary (pituitary gland)
  • Tertiary (hypothalamus)
51
Q

What is primary hypothyroidism?

A
  • Lack of functional thyroid tissue

- Most common form >95%

52
Q

What is most common cause of primary hypothyroidism?

A
  • Acquired
  • Lymphocytic thyroiditis ~50%
  • Idiopathic follicular atrophy
  • Least likely to be secondary neoplasia
53
Q

Iatrogenic causes of primary hypothyroidism

A
  • Surgery
  • Radioactive iodine therapy
  • Anti-thyroid medications
54
Q

How common is congenital primary hypothyroidism?

A
  • Rare
55
Q

Cretinism

A
  • Thyroid gland agenesis or dysgensis
  • Dyshormonogenesis (thyroid peroxidase deficiency)
  • Deficient dietary iodine
  • Ingestion of goitrogens
56
Q

Why don’t you see congenital primary hypothyroid ism that often?

A
  • Early death so may go undiagnosed

- Disporportionate dwarfism

57
Q

Secondary hypothyroidism

A
  • Imparied secretion of TSH from the pituitary gland
58
Q

Acquired causes of 2° hypothyroidism

A
  • Neoplasia
  • Illness, malnutrition
  • Pituitary suppression, e.g. glucocorticoid administration
59
Q

Congenital causes of 2° hypothyroidism

A
  • Cystic Rathke’s pouch

- Other pituitary hormone deficiencies, e.g. ADH

60
Q

Tertiary hypothyroidism

A
  • Lack of TRH in the hypothalamic supraoptic and paraventricular nuclei
  • Never documented in the dog
61
Q

Signalment of hypothyroidism

A
  • RARE under one year
  • Peak incidence around 4-6 years
  • No sex predisposition
  • Dobies, Golden and Labrador Retrievers, Dachshunds, Cocker Spaniels
62
Q

Clinical signs of hypothyroidism

A
  • 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
Q

Dermatologic signs with hypothyroidism

A
  • > 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
Q

Why do dogs with hypothyroid have wear of their hair?

A
  • Thyroid hormones needed for initiation of anagen phase
65
Q

What is myxedema?

A
  • Severe cases
  • Excess mucopolysaccharides (+hyaluronic acid in dermis)
  • Results in tragic facial expression (more advanced often)
66
Q

Recurrent infections with hypothyroidism

A
  • Otitis externa
  • Pyoderma
  • Effect on immune system
  • Effect on barrier function
  • may be their only sign
67
Q

Other clinical signs with hypothyroidism

A
  • Cardiovascular effects
  • Ocular abnormalities (rare)
  • Neurologic abnormalities (from segmental demyelinization)
  • GI abnormalities
  • REproductive abnormalities
  • Myxedema coma
68
Q

Diagnostic tests for hypothyroidism

A
  • 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
Q

Which drugs alter thyroid hormones?

A
  • Glucocorticoids

- TMS antibiotics

70
Q

How do glucocorticoids affect thyroid hormones?

A
  • Decrease TT4, free T4
  • Decrease T4 to T3 conversion
  • Decrease TSH
  • Could cause a false positive I think
71
Q

How do trimethoprim-sulfa antibiotics alter thyroid hormones?

A
  • Inhibits iodine conversion
  • Decrease TT4, decrease free T4, and increase TSH
  • True but reversible hypothyroidism
72
Q

Diagnosis of hypothyroidism

A
  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
Q

Medication for treatment of hypothyroidism

A
  • L-thyroxine
74
Q

HPA axis for cortisol

A
  • 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
Q

Appearance of adrenal glands with pituitary dependent hyperadrenocorticism

A
  • With pituitary dependent it produces a lot of ACTH and causes hypertrophy of the adrenal glands
76
Q

Appearance of adrenal glands with adrenal dependent hyperadrenocorticisim

A
  • 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
Q

What are the five P’s of hyperadrenocorticism?

A
  • 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
Q

Causes of panting with Cushing’s

A
  • THoracic fat
  • Abdominal distention
  • Muscular weakness
  • Thromboembolic complicatiosn
  • Many small breed dogs also have mitral insufficiency, collapsing trachea, etc.
79
Q

Appearance of alopecia with Cushing’s

A
  • Bilateral, symmetric
  • Often spares head and extremities
  • Atrophy of hair follicles
  • Nonpruritic
  • May fail to regrow their hair
  • Hyperpigmentation
80
Q

Common age of dogs with Cushing’s

A
  • Middle to older dogs
81
Q

Common breeds for hyperadrenocorticism

A
  • Bostons, Dachshunds, Boxers, Shih tzus
82
Q

Dermatologic signs with Cushing’s

A
  • 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
Q

What may be the only sign associated with Cushing’s?

A
  • Recurrent pyodermas
84
Q

What are the 5 P’s?

A
  • Polydipsia
  • Polyuria
  • Polyphagia
  • Panting
  • Pendulous abdomen
85
Q

Other clinical signs associated with Cushing’s

A
  • Urinary tract infections
  • Muscle atrophy
  • Generalized weakness
86
Q

More serious complications with Cushing’s

A
  • PTE
  • Cerebral infarct
  • Glomerulonephritis
  • Hypertension
  • Opportunistic infections
  • Diabetes mellitus
  • Acute pancreatitis
  • Pyelonephritis
  • Pituitary macroadenomas
87
Q

What should you immediately think with dermal atrophy or milia?

A
  • You really should be thinking steroids
88
Q

Comedomes

A
  • Keratin plugged follicles
89
Q

Signs associated with pyoderma

A
  • Papules
  • Pustules
  • Crusts
  • Epidermal collarettes
  • patchy alopecia
  • +/- Pruritus
90
Q

Diagnosis of Cushing’s

A
  • History
  • Clinical signs
  • Minimum data base (CBC/Chem/UA
91
Q

CBC signs with Cushing’s

A
  • Lymphopenia and eosinopenia

- Monocytosis and neutrophilia

92
Q

Chemistry changes with Cushing’s

A
  • ALP elevated (85-95%)
  • Mildly elevated ALT
  • Cholesterol
93
Q

UA changes with Cushing’s

A
  • Dilute
94
Q

Screening tests for Cushing’s

A
  • ACTH Stimulation test
  • Low dose dexamethasone suppression test
  • Urine cortisol to creatinine
95
Q

Differentiating tests

A
  • Sometimes LDDST
  • HDDST
  • Endogenous ACTH
  • Advanced imaging (AUS/CT/MRI)
96
Q

Treatment of HAC

A
  • Trilostane (not benign; need to make sure diagnosis is correct)
  • Lysodren
97
Q

Who gets Alopecia X?

A
  • Pomeranians
  • Poodles
  • Nordic breeds
98
Q

Age of dogs with alopecia X?

A
  • 1-10 years of age
99
Q

Sex of dogs with Alopecia X?

A
  • Males and females equally
100
Q

Clinical signs of Alopecia X?

A
  • 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
Q

Pathomechanism of Alopecia X?

A
  • Unknown

- Defect of anagen hair cycle?

102
Q

Diagnosis of Alopecia X?

A
  • Rule out other causes of endocrine alopecias
  • Hypothyroidism and Cushing’s
  • +/- biopsy to rule out sebaceous adenitis
103
Q

Treatment possibilities for Alopecia X?

A
  • Melatonin (most benign treatment; up to 40% may regrow hair); may take 3-4 months
  • Neutering of intact dogs (castration responsive dermatosis)
104
Q

Treatments NOT recommended for Alopecia X?

A
  • 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
Q

WHen does pattern alopecia typically start?

A

<1 year of age

106
Q

Progression of pattern alopecia/

A
  • Typically born with normal hair coat then develops alopecia
107
Q

What are the four syndromes of pattern alopecia?

A
  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
Q

When does cyclic flank alopecia tend to occur?

A
  • Develops during periods of short day length (fall/winter/spring)
109
Q

What can resolve cyclic flank alopecia? Is it always effectie?

A
  • UV light exposure

- Not always

110
Q

Breed predispositions for cyclic flank alopecia

A
  • Airedales
  • Boxers
  • English Bulldogs
  • Can be hyperpigmented
  • Serpiginous (all over)
111
Q

Diagnosis of cyclic flank alopecia

A
  • 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
Q

Where is cyclic flank alopecia most often seen/

A
  • PNW and northern parts of the US
113
Q

Age of dogs with seasonal trunk alopecia or cyclic flank alopecia?

A
  • 1.5-4.5 years
114
Q

What is “witches foot”?

A
  • Deformed telogen follicles described by pathologists
115
Q

Treatment for cyclic trunk alopecia

A
  • Melatonin may shorten duration and prevent recurrence
  • Increase UV sunlight
  • Benign neglect
116
Q

Biopsy of pattern alopecia/baldness

A
  • Small miniature sized follicles and adnexa
  • Small anagen hairs
  • Not always definitive
117
Q

Treatment for pattern alopecia/baldness

A
  • Melatonin?

- Benign neglect

118
Q

Excessive shedding - when is normal shed cycle?

A
  • spring and fall
119
Q

In normal shedding, what should not be created with epilation?

A
  • Alopecic area
120
Q

What can cause more shedding?

A
  • Hyperexcitable or nervous animals
121
Q

What should you check for if there has been a change in shedding?

A
  • Endocrinopathies
122
Q

What to do for excessive shedding

A
  • Remove the dead hairs, diet changes, increased free fatty aids, adjust light and/or temperature

Dermatology (15 decks)

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