The itchy and scabby horse Flashcards
List 4 broad conditions that can cause pruritus
ectoparasites
bacterial/ fungal- especially if chronic- pruritus occurs 2ndry
hypersensitivity
drug reactions
List 4 types of ectoparasites that cause pruritus in horses
mites
lice
biting flies/ insects
Oxyuris equi
List 3 types of mites that affect horses
Chorioptes spp
Psoroptes spp
Trombicula spp
where are lesions typically found with chorioptes equi
distal limb +++
groin/abdomen
where are lesions typically found with Trombicula autmnalis
head and legs (+++)
when are lice common in horses
in winter months
crowded barns
Clinical signs of lice in horses
“Moth-eaten” “Snow flake” appearance coat
Mane, base of tail and dorsum most common
Severe pruritus, self-mutilating, biting, rubbing
Alopecia, excoriation, serum exudation
Describe what biting lice look like
small, yellowish, broad flatted head feeds on scales
Describe what sucking lice look like
dark colour blood sucking, narrow head, slightly bigger
Describe how to treat chorioptes equi
dormectin injection
Fibronil spray
How to treat Trombicula autunnalis
Lime sulphur solution
pyrethrin spray
How to treat Psoroptes equi
oral macrocytic lactones (ivermectin or moxidectin)
lime sulphur solution
pyrethrin
How to treat lice in horses
permethrin pour-on
fibronil
Cliical signs of Oxyuris equi (Pin worm)
Once the female is fertilized migrates to anus to lay eggs>intense pruritus
Rubbing tail, broken hair on tail head, abrasions on perineum
How to treat Oxyuris equi
ivermectin or pyrantel by mouth
when does Culicoides hypersensitivity tend to occur
= sweet itch
Develops early in live (3-4yo) but worsen with age
Seasonal presentation: Spring-early autumn
Clinical signs of Culicoides hypersensitivty
dorsal or ventral lesion distribution
Pruritus
Crusted papules: mane, rump, base of the tail that extend to face, pinna, neck
List 3 ways to manage Culicoides hypersensitivity
stable horse at night wit fly-screen
keep horses away from water sources
apply permethrin pour-on - or other fly repellent
where do skin lesions generally occur with food allergies in horses
Face, neck, trunk lesions, angioedema and urticaria common
Where do skin lesions occur with contact dermatitis
Localised in areas in contact with tack predominantly
List 5 broad categories of causes of crusting/ scaling in horses
bacteria
Dermatophytosis
Pemphigus
parasites
chronic diseases
what is dermatophilosis congolensis also know as
rain scald/rot
List 4 risk factors for dermatophilosis congolensis
Poor nutrition
poor hygiene (sweaty horses)
high temperature and humidity
low-immunity
Describe clinical signs of dermatophilosis congolensis
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
Describe how to manage rain scald
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
Describe local treatment of rain scald
antiseptic washes
daily application of 5% K-permangante for 5 days
after washing dry horse with towel
Describe systemic treatment of rain scald
if highly exudative and painful cases +/- 2ndry infections
penicillin 3-5 days
TMPS for 2 wk
Describe the lesions seen with dermatophytosis (ringworm)
erected hairs in circular areas, typically silvery and slightly scaly extending centripetally»circular areas of alopecia
which horses are most likely affected by dermatophytosis
young horses more likely affected
Desribe how dermatophytosis is spread
Normally spread through contaminated girth, boots, clippers, brushes, etc
Mechanical disruption of skin is necessary for fungal colonization
Describe management of dermatophytosis
possibly Zoonotic- wear gloves
correct nutrition/ primary immuno-suppression
stop training
isolate
clean and disinfect tack
what do we see with photosensitization
non-pruritic crust in white areas
describe type 1 photosensitization
ingestion of photdynamic agent- plants
ST. Johns wort
Perennial ryegrass
Describe type 2 photosensitization
congenital disease
Describe type 3 photosensitisation
liver failure most common cause
How to manage photosensitization
treat primary problem
remove from pasture
apply sunscreen
cover affected areas until healing
Describe Pemphigus
exfoliative dermatitis due to type 2 hypersensitivity
How to diagnose Pemphigus
biopsy
How to treat Pemphigus
long-term glucocorticoids- immuno-suppressive
omega fatty acids
vit E supplementation
sunlight restriction
address underlying triggers
Describe Onchocera
Microfilaria parasite lowering prevalence due to the use of macrocytic lactones dewormers (ivermectin/ moxidectin)
How to treat Onchocerca
macrocytic lactone - permanent leukoderma possible
Describe pastern dermatitis
Multifactorial syndrome affecting caudal aspect of the pasterns
Lots od predispositions
what generally causes pastern dermatitis
Staphylococcus aureusandDermatophilus congolensis primary pathogens»fungi (Malassezia and Trichophyton)
Describe diagnostic approach/plan and management to pastern dermatitis
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
List 4 causes of ulcerative lesions in horses
virus- EHV-3, vesicular stomatitis
neoplasia- SCC
pressure sores
Summer sores
where do skin lesions occur in EHV-3
Lesions on the vulva, perineum, penis, prepuce and testicles
Oral and lip ulcers
How to manage Urticaria
identify trigger
wash skin if environmental trigger
cold hosing may improve clinical signs
steroids
cetirizine
omega fatty acids
Describe Vitiligo
Idiopathic depigmentation
Most common in grey horses
Around eyes and lips
No treatment=permanent change
Decsribe areata
Auto-immune disease
Non-pruritic progressive thinning mane and tail
Areas of alopecia
Leukotrichia
Exclamation shape hair bulb but
Biopsy for confirmation
