Equine dermatology Flashcards
(17 cards)
Main 5 diagnostic tool for a derm horse case.
- Skin scrape
- Coat/skin brushing
- Hair pluck
- Impression smear
- Biopsy
How do you take a skin scrape?
Scalpel blade moistened with liquid paraffin, then scrape.
Look for:
* Parasites
Use for:
* Cytology
Hair do you do a hair pluck test?
- Mount in liquid paraffin
- Use for Dermatophyte culture (Ringworm)
- Look for lice eggs
Pruritus/itching in a derm case horse can indicate what parasite?
Oxyuris equi aka pinworms that come out their butt
Which 3 types of mites do horses get?
- Chorioptic mange by Chorioptes equi
- Dermanyssus gallinae
- Sarcoptes by Sarcopter scabiei variant equi (very rare though)
Biting midges are also known as
Culicoides
Describe equine pinworm infection.
Pinworm Oxyuris equi
* Adults live in the colon and rectum
* Females migrate to the anus to lay eggs in the perineal area.
Signs of infection:
* Rubbing their tail on stuff, broken tail hair.
* Super itchy
Use Scotch tape test to pick up eggs to check under microscope.
No specific therapy
* Pyrantel pamoate
* Ivermectin
* Moxidectin
Wash the perineal area for 3 days with warm water+soap.
Describe Pediculosis in horses.
aka Lice infestation
- Biting lice called Bovicola equi (Damalinia equi), suckling lice called Haematopinus asini.
Signs of lice in horses include
* Rubbing tail and mane, hair loss
You can see them by Visual inspection.
Tx with Pour-on solution:
* Deltamethrin 10mg/ml (10ml per horse)
* Eprinomectin 5mg/ml (0,5mg/kg)
* Clean Environment & equipment
Describe chorioptosis in horses.
Chorioptic mange caused by Chorioptes equi.
- Itching and scratching
- Legs, tail, sometimes belly or back
- Hair loss
- Thickened, scabby skin
- Crusting and scaling on the skin
Diagnose with skin scrapes.
Tx:
* Wash horse with shampoo
* Fipronil spray 0,25% or spot on (Soak the skin, Apply on every leg)
* Doramectin 10mg/ml (2 subcutaneous injections at 3mg/kg, two weeks apart)
* 5% Lime Sulphur Solution wash, no rinse.
* 1% Selenium Sulphide bath once a week for 4 weeks.
Describe Insect bite hypersensitivity in horses.
Also called sweet itch.
- Allergic reaction to the saliva of insects, mainly Culicoides midges (tiny biting flies).
Manage with:
* Allergen Avoidance
* Skin Barrier Repair (oral fish oil, linseed oil; topical conditioner)
* Anti-inflammatories
* Immunotherapy
* Clean the stables thoroughly, remove standing water.
* Use rugs and fly masks.
* Use insect repellents on the horse.
Tx with:
* topical or systemic Glucocorticoids
* Anti-histamines
* Allergen specific immunotherapy (ASIT) Intradermal injections
* Insol® Trichophyton species vaccine
name 3 antihistamines used in horses
- Cetrizine 0.2-0.4 mg/kg PO BID
- Diphenhydramine 1-2 mg/kg BID
- Hydroxyzine 1 mg/kg SID-TID
diff between Dermatophytosis and dermatophilosis
Fungal
* Dermatophytosis (ringworm)
Bacteria
* Dermatophilosis (rainrot)
Describe Dermatophytosis in horses.
Zoonotic!
Is Ringworm:
* Trichophyton equinum
* Microsporum gypseum
Circular areas of alopecia with scaling, crusting.
* Non-pruritic or mildly itchy
* Face, neck, girth, saddle area
Dermatophytosis diagnosis and tx in horses involves:
- Fungal culture
- Wood’s lamp (NB only certain Microsporum spp. fluoresce)
Antifungal topical treatment
* Enilconazole, miconazole
But, self-limiting 1-3 months.
Describe dermatophilosis in horses.
Also known as rain scald, rain rot.
Caused by Dermatophilus congolensis
* Gram-positive actinomycete bacterium.
Occurs to/on Damaged or constantly wet skin e.g. from Tight, moist rugs.
Dermatophilus bacteria form hyphae-like filaments and zoospores.
Induces a neutrophilic inflammatory response → pustules, crusting. Characteristic “Paintbrush lesions”:
* Tufts of matted hair over crusted exudate
* Raw, moist skin
* on the Back most commonly
* Face, neck, legs can be affected too.
NB is Mildly painful!
Tx of dermatophilosis in horses.
- Dry environment, Keep without rug
- 4% Clorhexidine shampoo wash
- Systemic antimicrobials with TMS
