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CVSOH BVSc4 > Derm - Alopecia > Flashcards

Derm - Alopecia Flashcards

1
Q

What makes up the structure of the hair follicle?

A

Hair bulb
Arrector pili muscle
Sweat gland
Sebaceous gland

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2
Q

What are the three stages of the hair cycle?

A

Anagen - active growth
Catagen - involution of the hair shaft
Telogen - no growth (until anagen displaces the old hair for a new one)

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3
Q

What do anagen hairs look like?

A

Rounded bulb like appearance

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4
Q

What do telogen hairs look like?

A

Tapered brush like root

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5
Q

What causes hair growth?

A

Keratinocytes form the hair shafts from the matrix of the hair bulb
These then differentiate into hair shaft and inner root sheath
Stem cell region replace epidermal keratinocytes
Daughter cells migrate up and out of the hair follicle

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6
Q

What molecules control the development of the hair follicle? What are they synthesised by?

A

Morphogens
Synthesised by tissue cells adjacent to the follicle or hormones

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7
Q

What are the 3 main pathogenetic mechanisms that result in alopecia?

A
  1. Destruction of normally growing hair follicles and hair shafts
  2. Abnormalities of the hair cycle causing atrophy and regression of hairs
  3. Abnormalities of the hair follicle/shaft causing structural defects
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8
Q

What are some causes of destruction of normally growing hair follicles?

A

Traumatic alopecia - self trauma
Folliculitis - staph infection, demodex, dermatophytosis
Inflammatory alopecia - vascular diseases, sebaceous adenitis, neoplasia

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9
Q

How do vascular disease cause alopecia?

A

Loss of blood supply to skin results in damage to hair follicle

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10
Q

How does sebaceous adenitis cause alopecia?

A

Inflammation of sebaceous gland spills over into hair follicle

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11
Q

What is the most common cause of abnormal hair cycles causing hair follicle atrophy?

A

Endocrinopathies

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12
Q

What is the most common cause of abnormal hair follicle/shaft developent?

A

Follicle dysplasia/dystrophy
Associated with certain breeds, coat types/colours

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13
Q

What is dermatophytosis?

A

Ringworm

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14
Q

How does dermatophytosis cause alopecia?

A

Arthrospores adhere to keratinocytes and cause microtrauma to the skin
Then invades epidermis
Enzymes breakdown keratinocytes

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15
Q

What is the incubation period for dermatophytosis?

A

1-3 weeks

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16
Q

What is the organism that causes dermatophytosis most commonly in cats and dogs?

A

Microsporum canis

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17
Q

What is the organism that causes dermatophytosis from exposure to rodents?

A

Trichophyton

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18
Q

What type of cat is particularly susceptible to dermatophytosis becuase it cant mount a good immune response?

A

Persian cats

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19
Q

What are the clinical signs of dermatophytosis?

A

Alopecia
Scale
Central healing
Folliculitis and furunculosis

20
Q

How can you diagnose dermatophytosis?

A

Fungal culture of hair and scale samples by the lab
PCR - quick but too sensitive, false positives possible
Wood’s lamp

21
Q

How can you collect samples to diagnose dermatophytosis?

A

Brush affected areas
Plucking
Scraping

22
Q

How does a Wood’s lamp work for diagnosing dermatophytosis?

A

Examine animal in a dark room to show fluorescence in the lesions/hair
Only works for M. canis
Pluck the hairs htat light up

23
Q

How can you treat dermatophytosis?

A

Animals can self cure
Topical therapy can reduce transmission

24
Q

Should you clip animals with dermatophytosis?

A

May help to reduce environmental and host load but may spread disease in the affected animal
Infection can spread up to 6cm from obvious lesions

25
Q

What are some examples of topical therapy for dermatophytosis?

A

Shampoos - malaseb (chlorhexidine and miconazole)
Dips - enilconazole
Wash twice weekly, soak for 10 mins

26
Q

What are some systemic therapies for dermatophytosis?

A

Itraconazole
Ketoconazole

27
Q

When should you use systemic therapy to treat dermatophytosis?

A

Generalised infection
Chronic infection
Breeds predisposed - persian, yorkie
In trichophyton infections

28
Q

What kind of dermatophytosis do horses get?

A

Trichophyton

29
Q

How is dermatophytosis spread in horses?

A

Direct contact
Infected tack and grooming

30
Q

How do you treat equine dermatophytosis?

A

Spontaneous resolution
Topical therapy - miconazole shampoo
Disinfection of tack and premises

31
Q

How do you diagnose demodex?

A

Deep skin scrapings

32
Q

When does generalised demodicosis generally occur?

A

Young dogs less than 18 months

33
Q

What is generalised demodicosis?

A

More than 5 lesions
One major body region affected
two or more feet

34
Q

What can cause adult onset demodex?

A

Immune suppression
Corticosteroids
Hyperadrenocorticism
Chemo
Neoplasia

35
Q

What is juvenile onset demodicosis?

A

Mild disease
Lesions in focal areas - not generalised
Will spontaneously resolve and lead to resistance

36
Q

How can you treat demodex?

A

Acaricidal treatment - Isoxazolines
Manage bacterial pyoderma with chlorhexidine baths

37
Q

What causes hair follicle dysplasia?

A

Abnormality of the merphogens that influence the development of the hair follicle

38
Q

What occurs in hair follicle dysplasia?

A

Abnormal hair shaft or follicle that doesnt allow hair growth - alopecia

39
Q

What are affected with hair follicle dysplasia?

A

Dogs - congenital or acquired
Chinese crested dogs
Dilute coat colours - blue, grey

40
Q

How do you diagnose hair follicle dysplasia?

A

Histopathology
Rule out endocrine disease

41
Q

How do you treat hair follicle dysplasia?

A

You cant

42
Q

What are some endocrine causes of alopecia?

A

Hyperadrenocorticism
Sertoli cell tumour

43
Q

What is cyclical flank alopecia?

A

Pigment changes in the skin and alopecia
Exact cause unknown, but is hormonal

44
Q

What breeds does cyclical flank alopecia affect?

A

Boxers, airedales, English bulldogs

45
Q

What is alopecia X

A

Aetiology poorly understood
Affects flank - spares head and legs
Hyperpigmentation
No other clinical signs
Response to treatments variable - neutering and melatonin

CVSOH BVSc4 (86 decks)

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