Equine Dermatologic Conditions

Front 1

What clinical signs are assoc. w/ Staph infection?

Back 1

circular alopecia, crusts, papules, draining tracts on saddle, lumbar, distal limbs, pastern

Front 2

What is the tx for Staph infection?

Back 2

- local infection: topical AB washes: chlorhexidine, silver sulfadiazine, mupiricin, ethyl lactate (work ~50% of the time)
- more extensive involvement: systemic ABs (TMS, Enrofloxacin)

Front 3

What are the clinical signs of insect allergies?

Back 3

pruritis, alopecia, excoriations, lichenification, papules

Front 4

What is the tx for insect allergies?

Back 4

- steroids: IV &/or PO to break cycle
- antihistamines: not effective in horses (difference in H1 receptor?)
- prevention: vector control (sprays, washes, fans, screens, masks, sheets)

Front 5

What are the clinical signs of atopic dermatitis?

Back 5

pruritis, alopecia, excoriation, lichenification, crusts, scales, erythema, urticaria

Front 6

What is the tx for atopic dermatitis?

Back 6

hyposensitization, steroids, antihistamines, topicals

Front 7

What are the clinical signs of food allergy?

Back 7

generalized pruritis, urticaria, diarrhea, reactive airway dz

Front 8

What is the pathogenesis of dermatophilosis?

Back 8

- Dermatophilus congolensis
- zoospores on horse’s coat activated by wet conditions
- horse to horse spread by insects
- natural immunity: heritable?
- usually occurs in fall, winter, early spring
- skin barrier damage: trauma, insets, chronic moisture

Front 9

What clinical signs are assoc. w/ dermatophilosis?

Back 9

crusts (initial lesion papular), painful, NOT pruritic, “paintbrush” lesions: most severe on distal limbs, dorsum

Front 10

How is dermatophilosis diagnosed?

Back 10

- signs, hx
- examine crusts on slide, gram stain, ink, Dif-Quik
Gram + branching filamentous organisms: railroad tracks
- culture, bx

Front 11

What is the tx for dermatophilosis?

Back 11

- most cases self-limiting
- topical antifungals, antibacterial washes (iodophors, chlorhexidine)
- if severe: systemic ABs (TMS, P/G)
- control: change environment

Front 12

What are the clinical signs of dermatophytosis?

Back 12

usually circular alopecia & crusts assoc. w/ tack or grooming
may have urticaria initially

Front 13

How is dermatophytosis diagnosed?

Back 13

- ddx: bacterial folliculitis (may coexist)
- Wood’s lamp rarely (+)
- microscopic exam of hairs: difficult
- bx: quick, use special stains (dx 70%)
- fungal culture (dx 90%)

Front 14

What is the tx for dermatophytosis?

Back 14

- spontaneous resolution
- antifungal washes: lime sulfur, Malaseb (miconazole + chlorhexidine)
- systemic antifungals: griseofulvin (not if pregnant)
- spray eniloconazole: environment, equipment
- fumigate w/ formaldehyde: equipment

Front 15

What are the causes of equine pastern dermatitis?

Back 15

- pastern folliculitis: S. aureus; affects posterior aspect of multiple limbs, may have papules  suppuration, erosions
- irritant or contact dermatitis
- dermatophilosis
- dermatophytosis
- photosensitization
- chorioptic mange: draft horses; typically around heels, very pruritic

all causes --> pastern leukocytoclastic vasculitis

Front 16

What are the clinical signs of equine pastern dermatitis?

Back 16

focal areas of erosion & ulceration, w/ pain, edema
photoactivated: more common in horses w/ white limbs

Front 17

How is equine pastern dermatitis diagnosed & treated?

Back 17

dx: bx

tx
- many cases resolve on own
- when tx required: costly & difficult to tx
- antibacterial shampoos, topical AB ointments, antifungal shampoos, sprays, dips, topical steroids, systemic ABs, systemic antifungals, antiparasitics, immunomodulator medications

Front 18

What is the pathogenesis of hyperelastosis cutis?

Back 18

- affects quarter horses: Poco Bueno line (autosomal recessive)
- collagen deficit: lack of adhesion w/in dermi

Front 19

What are the clinical signs of Pythiosis?

Back 19

- cutaneous & SQ infiltration: abdomen, pectorals, necks, lips, distal limbs
- granulomas rapidly enlarge
- splitting of dermis & epidermis, lots of exudate, concretions of eosinophils

Front 20

How is Pythiosis diagnosed & treated?

Back 20

dx: culture, bx, serology on core yellow necrotic tissue (“kunkers”)

tx
- wide surgical excision
- iodides: KI (oral), NaI (IV)
- vaccine if seropositive

Front 21

What are ddx for pruritis?

Back 21

#1: parasites
infection: Malasezzia, Staph (superficial), Strep, Corynebacterium, or Pseudomonas (deep)
hypersensitivity

Front 22

ddx for scaling & crusting

Back 22

dermatophilosis
dermatophytosis