Equine dermatology pt 1

Question 1

functions of skin as an organ

Answer 1

§Shape and form
§Enclosing barrier
§ Temperature regulation
§Produces adnexa
§ Reservoir
§ Immunoregulation
§Sensory perception

Question 2

layers of the skin from top to bottom

Answer 2

• stratum corneum > dead keratinocytes
• stratum lucidum
• stratum granulosum > lamellar granules
• stratum spinosum > keratinocytes, sparse langerhans cells, melanocyte at base
• stratum basale
• dermis

Question 3

what is a merkel cell? where do we find it

Answer 3

§Slow-adapting mechanoreceptors
- in the stratum basale, connect to sensory neuron

Question 4

melanocytes are derived from

Answer 4

neural crest

Question 5

what is a langerhans cell

Answer 5

§ Dendritic, antigen-presenting cell

Question 6

what is the function of the basement membrane zone

Answer 6

§Anchors epidermis to dermis

Question 7

what do we find in the dermis

Answer 7

§Collagen and elastin § Fibroblasts
§Dermal dendrocytes

Question 8

§Phases of hair growth

Answer 8

§ Anagen: Growth phase
§ Catagen: Transitional phase
§ Telogen: Resting phase

Question 9

physical exam for skin issue includes:

Answer 9

§Perform complete examination
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§Skin lesions and distribution:
§Primary lesions
§Secondary lesions
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§Remember to check:
§Mucous membranes
§Mucocutaneous junctions
§Inguinal region
§Feathered limbs
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§Record lesions and measure!

Question 10

§Disorders of pigmentation
- leukoderma disorders

Answer 10

§ Vitiligo
§ Onchocerciasis
§Lupus erythematous
§Pressure sores
§ Burns, freezing, UV

Question 11

§Disorders of pigmentation
- leukotrichia disorders

Answer 11

§ Reticulated
§ Spotted
§ Hyperesthetic

Question 12

Disorders of hair

Answer 12

§Mane and tail dystrophy
§Curly coat
§ Hirsutism
§Alopecia areata
§Anagen defluxion
§ Telogen defluxion
§Naked Foal Syndrome

Question 13

what is a Macule

Answer 13

§ Erythema, hyper- or hypopigmentation
§ Up to 1cm in diameter
§ Not raised

Question 14

what is a patch

Answer 14

§ Same appearance as macule
§ Greater than 1-2 cm

Question 15

what is a papule

Answer 15

§ A circular, solid erythematous elevation of the skin up to 1cm in diameter

Question 16

what is a plaque

Answer 16

§ Larger, flat topped elevation of coalescing papules

Question 17

what is a nodule

Answer 17

§ Large papule, >1cm
§Raised and may extend into dermis

Question 18

what is a pustule

Answer 18

§Small accumulation of purulent exudate

Question 19

what is wheal

Answer 19

§ Raised elevation of skin due to dermal edema
§Pitting edema

Question 20

what is a vesicle

Answer 20

§ Elevation in epidermis filled with clear
fluid
§ Up to 1cm in size

Question 21

what is a bulla

Answer 21

§ Vesicle > 1cm in size

Question 22

what is an erosion

Answer 22

§ Partial loss of epidermis
§ Excoriation= linear erosion

Question 23

what is an dermal ulcer

Answer 23

§ Complete loss of epidermis and partial loss of dermis

Question 24

EXUBERANT GRANULATION TISSUE
- how does it arise
- anatomic location most common
- issues
- Tx

Answer 24

§Granulation= phase of wound healing §Overproduction of fibroblasts
> Exuberant granulation
§Most common in distal limbs §Prevents further healing §Requires surgical debridement

Question 25

pediculosis in horses
- signs
- agents
- season
- Tx

Answer 25

§ Species specific, obligate parasites
§Severe pruritus
§Damalinia equi- Biting louse
§Haematopinus equi- Sucking louse §More common in winter
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§ Treatment
§200ug/kg oral ivermectin every 2 weeks x 3 §500ug/kg topical eprinomectin once weekly x 4
§Pyrethrin spray/ powder every 14 days twice

Question 26

agents of mange in the horse

Answer 26

§ Sarcoptes scabei var. equi
§ Psoroptes equi
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§Chorioptes bovis

Question 27

Sarcoptes scabei var. equi
- character, contagion, signs
- anatomic locations

Answer 27

§ Highly contagious and zoonotic
§ Burrowing mite
§ Pruritic
§ Head, neck, and shoulders to generalized

Question 28

Psoroptes equi
- type of mite, signs, anatomic locations

Answer 28

§ Non-burrowing mite
§ Pruritic
§ Face, ears, areas with high hair density

Question 29

mange due to Sarcoptes scabei var. equi and Psoroptes equi
Tx

Answer 29

§ 200ug/kg oral ivermectin twice 14 days apart
§ 400ug/kg oral moxidectin once

Question 30

Chorioptes bovis clinical signs, where found

Answer 30

Mange
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§Survives in environment
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§ Clinical signs:
§ Severe pruritis
§ Erythema
§ Alopecia
§ Excoriation
§ Scales/ crusts
§ Lichenification

Question 31

chorioptic mange, Dx, Tx

Answer 31

Diagnosis
§Scrape non-traumatized areas
§Evaluate under microscope
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Treatment
§Remove all feathers
§Bathe with medicated or oatmeal shampoo
§ Topical eprinomectin or fipronil
§Oral ivermectin or moxidectin
§ Treat all horses and premise

Question 32

habronemasis
- common name
- agents
- season
- signalment

Answer 32

“Summer sores”
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Etiology
§ Habronema muscae
§ Habronema majus
§ Draschia megastoma
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Spring and summer
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Increased risk
§ Arabians
§ Grey horses
§ Coat color dilutions

Question 33

habronemiasis clinical signs

Answer 33

§Ulcerated lesion
§Non-healing wound
§ Contains gritty, yellow granules

Question 34

habronemiasis Dx, Tx

Answer 34

Diagnosis
§ Biopsy
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Treatment
* Oral ivermectin or moxidectin
* Topical care:
§Compounded ointment
§Surgical debridement
§Bandage if possible
§Fly control