The itchy and scabby horse

Question 1

List 4 broad conditions that can cause pruritus

Answer 1

ectoparasites
bacterial/ fungal- especially if chronic- pruritus occurs 2ndry
hypersensitivity
drug reactions

Question 2

List 4 types of ectoparasites that cause pruritus in horses

Answer 2

mites
lice
biting flies/ insects
Oxyuris equi

Question 3

List 3 types of mites that affect horses

Answer 3

Chorioptes spp
Psoroptes spp
Trombicula spp

Question 4

where are lesions typically found with chorioptes equi

Answer 4

distal limb +++
groin/abdomen

Question 5

where are lesions typically found with Trombicula autmnalis

Answer 5

head and legs (+++)

Question 6

when are lice common in horses

Answer 6

in winter months
crowded barns

Question 7

Clinical signs of lice in horses

Answer 7

“Moth-eaten” “Snow flake” appearance coat
Mane, base of tail and dorsum most common
Severe pruritus, self-mutilating, biting, rubbing
Alopecia, excoriation, serum exudation

Question 8

Describe what biting lice look like

Answer 8

small, yellowish, broad flatted head feeds on scales

Question 9

Describe what sucking lice look like

Answer 9

dark colour blood sucking, narrow head, slightly bigger

Question 10

Describe how to treat chorioptes equi

Answer 10

dormectin injection
Fibronil spray

Question 11

How to treat Trombicula autunnalis

Answer 11

Lime sulphur solution
pyrethrin spray

Question 12

How to treat Psoroptes equi

Answer 12

oral macrocytic lactones (ivermectin or moxidectin)
lime sulphur solution
pyrethrin

Question 13

How to treat lice in horses

Answer 13

permethrin pour-on
fibronil

Question 14

Cliical signs of Oxyuris equi (Pin worm)

Answer 14

Once the female is fertilized migrates to anus to lay eggs>intense pruritus
Rubbing tail, broken hair on tail head, abrasions on perineum

Question 15

How to treat Oxyuris equi

Answer 15

ivermectin or pyrantel by mouth

Question 16

when does Culicoides hypersensitivity tend to occur

Answer 16

= sweet itch
Develops early in live (3-4yo) but worsen with age
Seasonal presentation: Spring-early autumn

Question 17

Clinical signs of Culicoides hypersensitivty

Answer 17

dorsal or ventral lesion distribution
Pruritus
Crusted papules: mane, rump, base of the tail that extend to face, pinna, neck

Question 18

List 3 ways to manage Culicoides hypersensitivity

Answer 18

stable horse at night wit fly-screen
keep horses away from water sources
apply permethrin pour-on - or other fly repellent

Question 19

where do skin lesions generally occur with food allergies in horses

Answer 19

Face, neck, trunk lesions, angioedema and urticaria common

Question 20

Where do skin lesions occur with contact dermatitis

Answer 20

Localised in areas in contact with tack predominantly

Question 21

List 5 broad categories of causes of crusting/ scaling in horses

Answer 21

bacteria
Dermatophytosis
Pemphigus
parasites
chronic diseases

Question 22

what is dermatophilosis congolensis also know as

Answer 22

rain scald/rot

Question 23

List 4 risk factors for dermatophilosis congolensis

Answer 23

Poor nutrition
poor hygiene (sweaty horses)
high temperature and humidity
low-immunity

Question 24

Describe clinical signs of dermatophilosis congolensis

Answer 24

large oval lesions with a ‘paintbrush effect’
Lesions can be annular and often follow a “dribbling” or “scald line” pattern particularly in the dorsum and trunk

Question 25

Describe how to manage rain scald

Answer 25

wash tack keep horses dry after exercise Maintain the bedding clean and dry, avoid accumulation of manure Avoid sunlight in affected areas as it might aggravate irritation

Question 26

Describe local treatment of rain scald

Answer 26

antiseptic washes daily application of 5% K-permangante for 5 days after washing dry horse with towel

Question 27

Describe systemic treatment of rain scald

Answer 27

if highly exudative and painful cases +/- 2ndry infections penicillin 3-5 days TMPS for 2 wk

Question 28

Describe the lesions seen with dermatophytosis (ringworm)

Answer 28

erected hairs in circular areas, typically silvery and slightly scaly extending centripetally>>circular areas of alopecia

Question 29

which horses are most likely affected by dermatophytosis

Answer 29

young horses more likely affected

Question 30

Desribe how dermatophytosis is spread

Answer 30

Normally spread through contaminated girth, boots, clippers, brushes, etc Mechanical disruption of skin is necessary for fungal colonization

Question 31

Describe management of dermatophytosis

Answer 31

possibly Zoonotic- wear gloves correct nutrition/ primary immuno-suppression stop training isolate clean and disinfect tack

Question 32

what do we see with photosensitization

Answer 32

non-pruritic crust in white areas

Question 33

describe type 1 photosensitization

Answer 33

ingestion of photdynamic agent- plants ST. Johns wort Perennial ryegrass

Question 34

Describe type 2 photosensitization

Answer 34

congenital disease

Question 35

Describe type 3 photosensitisation

Answer 35

liver failure most common cause

Question 36

How to manage photosensitization

Answer 36

treat primary problem remove from pasture apply sunscreen cover affected areas until healing

Question 37

Describe Pemphigus

Answer 37

exfoliative dermatitis due to type 2 hypersensitivity

Question 38

How to diagnose Pemphigus

Answer 38

biopsy

Question 39

How to treat Pemphigus

Answer 39

long-term glucocorticoids- immuno-suppressive omega fatty acids vit E supplementation sunlight restriction address underlying triggers

Question 40

Describe Onchocera

Answer 40

Microfilaria parasite lowering prevalence due to the use of macrocytic lactones dewormers (ivermectin/ moxidectin)

Question 41

How to treat Onchocerca

Answer 41

macrocytic lactone - permanent leukoderma possible

Question 42

Describe pastern dermatitis

Answer 42

Multifactorial syndrome affecting caudal aspect of the pasterns Lots od predispositions

Question 43

what generally causes pastern dermatitis

Answer 43

Staphylococcus aureus and Dermatophilus congolensis primary pathogens>>fungi (Malassezia and Trichophyton)

Question 44

Describe diagnostic approach/plan and management to pastern dermatitis

Answer 44

take samples and clip hair clean with warm water and neutral soap dry throughly with towel avoid bandaging treat primary problem Warn owner: Long term and environmental management mandatory

Question 45

List 4 causes of ulcerative lesions in horses

Answer 45

virus- EHV-3, vesicular stomatitis neoplasia- SCC pressure sores Summer sores

Question 46

where do skin lesions occur in EHV-3

Answer 46

 Lesions on the vulva, perineum, penis, prepuce and testicles Oral and lip ulcers

Question 47

How to manage Urticaria

Answer 47

identify trigger wash skin if environmental trigger cold hosing may improve clinical signs steroids cetirizine omega fatty acids

Question 48

Describe Vitiligo

Answer 48

Idiopathic depigmentation Most common in grey horses Around eyes and lips No treatment=permanent change

Question 49

Decsribe areata

Answer 49

Auto-immune disease Non-pruritic progressive thinning mane and tail Areas of alopecia Leukotrichia Exclamation shape hair bulb but Biopsy for confirmation