Term
| What are the common dermatologic diseases of horses? |
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Definition
-bacterial folliculitis: pastern dermatitis
-dermatophytosis
-dermatophilosis
-ear conditions
-hypersensitivity: fly bite dermatitis, hives
-tail rubbing |
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Term
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Definition
| -inflammation of hair follicle with accumulation of inflammatory cells within follicle lumen |
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Term
| What are the causes of folliculitis? |
|
Definition
-Staph spp: coagulase positive
-Strep spp |
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Term
|
Definition
| -degeneration of hair follicle that leads to infection of surrounding dermis and subcutis |
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Term
| What are the clinical signs of bacterial folliculitis? |
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Definition
-rapid development: first sign is rughly circular areas of erect hairs
-regresses or proceds to smal painful papules
-papules develop an ulcerated central area: local edema and exudation
-usually not pruritic |
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Term
| What is the typical clinical presentation of bacterial folliculitis? |
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Definition
| -most commonly noted in areas of rubbing: saddle, rugs, harness, etc |
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Term
| What is the seasonality of bacterial folliculitis? |
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Definition
| -seen most commonly in later spring/summer |
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Term
| What diagnostic tests do we use for bacteriral folliculitis? |
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Definition
-bacterial culture/sensitivty
-biopsy |
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Term
| What is the culture method we use for bacterial folliculitis? |
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Definition
-locate intact pustule, do not clean with antiseptic
-use a sterile needle to obtain an aspirate, or use needle to open pustule prior to swabbing with cotton tip swab
-transport medium is essential |
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Term
| Describe the initial treatment of bacterial folliculitis? |
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Definition
-+/- clip hair
-wash infected area with water and dilute antiseptic
-leave scrub on skin 5-10 mins and rinse off with warm water |
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Term
| What are our antiseptic choices for treating bacterial folliculitis? |
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Definition
-chlorhexidine
-povidone-iodine scrub
-benzoyl peroxide products |
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Term
| For what do we use systemic antibiotic treatment? |
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Definition
| -used for bacterial skin diseases that are untreatable with topical therapy alone |
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Term
| What is the most commonly used antibiotic for bacterial folliculitis treatment? |
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Definition
| -Trimethoprim sulfamethaxazole |
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Term
| What is the most common cause of inabilit y to resolve skin infections due to bacterial folliculitis? |
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Definition
| -treatment is discontinued too early |
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Term
| What is the general treatment recommendation for bacterial folliculitis? |
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Definition
| -continue antibiotic therapy 7-10 days after skin surface healing |
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Term
| What are some fo the potential etiologies of pastern dermatitis? |
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Definition
-bacterial folliculitis
-dermatophilosis
-dermatophytosis
-contact dermatitis
-photosensitization
-chorioptic mange |
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Term
| What is the major clinical sign seen with pastern dermatitis? |
|
Definition
|
|
Term
| What is the predisposing factor for pastern dermatitis in horses? |
|
Definition
|
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Term
| What is pastern folliculitis? |
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Definition
| -superficial bacterial infection of pastern region |
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Term
| What are the common names for pastern folliculitis? |
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Definition
| -Scratches, Greasy heel, mud fever |
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Term
| What is the causative agent of pastern folliculitis? |
|
Definition
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Term
| What are the leesions of pastern foliculitis? |
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Definition
-papules/pustules
-untreated lesions coalesce, resulting in ulceration and suppuration (painful) |
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Term
| How do we diagnose pastern folliculitis? |
|
Definition
| -clinical appearance, culture, and smears |
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Term
| How do we treat pastern folliculitis? |
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Definition
-close-slip, clean, scrub with chlorhexidine or povidone-iodine, rinse thoroughly
-dry legs with clean towel for each leg
-topical creams/dessings containing silver sulfadiazine or antimicrobial
-recurrence common
-most commonly occurs with white legs
-clip and clean area
-change environment
-antimicrobial and astringent soaks and shampoos
-systemic antimicrobials |
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Term
| What is the etiology of dermatophytosis? |
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Definition
-Trichophyton equinum: most common but not zoonotic
-Microsporum equinum
-T. mentagrophytes
-T. verrucosum
-M. gypseum |
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Term
| What age of horse is predisposed to dermatophytosis? Is it contagious? |
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Definition
-young mroe predisposed
-contagious |
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Term
| How is dermatophytosis transmitted? |
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Definition
-fomites
-tack
-grooming techniques |
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Term
| Which of the etiologies of dermatophytosis is zoonotic? |
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Definition
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Term
| What are the clinical signs of dermatophytosis? |
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Definition
-lesions visible 7-21 days post infection
-lesion can expand/spread across body of horse for 2-4 months
-usually non pruritic
-erect hairs in circular areas 5-20 mm diameter
-localized inflammation, thickened skin
-7-10 days post infection: hair can be easily plucked: leaves a silvery, reddened area of exposred epidermis
-severe scaling and alopecia
-paint brush lesions |
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Term
| How do we diagnose dermatophytosis? |
|
Definition
-microscopic exam of plucked hairs: see fungal hyphae and put in dermatophyte test media
-response to treatment |
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Term
| What kinds of shampoos do we use to treat dermatophytosis? |
|
Definition
-chlorhexidine
-betadine
-miconazole |
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Term
| How do we treat dermatophytosis? |
|
Definition
-most resolve spontaneously in 6-12 weeks with access to sunshine is encourage
-tropical therapy is most commonly used treatment option |
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Term
| What are the sites commonly affected by dermatophilosis? |
|
Definition
-rump and topline
-saddle area around withers
-face and neck
-pasterns and heels
-cranial aspect of the hind cannon bones
-secondary cutaneous infection with Staph or Strep can occur |
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Term
| What is the etiology of dermatophilosis? |
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Definition
| -Dermatophilus congolensis |
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Term
| What does Dermatophilus congolensis look like on slides? |
|
Definition
-classic railroad track
-gram positive
-facultative anaerobic actinomycete |
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Term
| What are the most important predisposing factor of dermatophlosis? |
|
Definition
|
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Term
| What are the clinical signs of dermatophilsois? |
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Definition
-infectious superficial pustular dermatosis
-hair easily epilates
-scab with hairs attached like a paint brush |
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Term
| What is the treatment of dermatophilosis? |
|
Definition
-shampoos: chlorohexidine, betadine
-keep skin dry
-fresh towels to dry distal limbs after baths
-contagious |
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Term
| What is the systemic treatment of dermatophilosis? |
|
Definition
-procaine penicillin
-trimethoprim sulfamethoxazole |
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Term
| Dermatophilosis is a contagious condition. How do we combat this? |
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Definition
-isolate affected horses
-skin debris should be disposed
-all grooming equipment/tack should be washed and sterilized with tertiary amine disinfectant |
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Term
| What is indicated when you have difficulty passing the bridle or halter over the ears of your horse? |
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Definition
| -pain from ear conditions |
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Term
| What are the differentials for head shaking? |
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Definition
-behavior
-photic trigeminal neuritis
-temporohyoid osteopathy
-ear mange
-ear tricks |
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Term
| What are the primary clinical signs of otobius megnini? |
|
Definition
-pain
-msucle cramping
-muscle fasciculations
-sweating
-pawing
-prolapse of third eyelid
-inc CK |
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Term
| What is the etiology of aural plaques in the horse? How is it transmitted? Age predesposition? |
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Definition
-papilloma virus
-flies
-all ages affected |
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Term
| What is the etiology of warts in the horse? Age rpedisposition? |
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Definition
-papilloma virus
-young horses |
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Term
| Where on the horse do warts usually occur? |
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Definition
|
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Term
| Do aural plaques spnteneously regress? |
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Definition
|
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Term
| Do warts spontaneously regress? |
|
Definition
-2-4 month sponteneously regression
-can crush to initiate immune response |
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Term
| What are the common locations of tick dermatoses in the horse? |
|
Definition
-ears
-mane
-base of tail
-axilla and groin |
|
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Term
| What is the common tick causing tick dermatoses in the horse? |
|
Definition
|
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Term
| What are the etiologies of urticaria? |
|
Definition
-airborne allergens
-drugs
-vaccines
-feed
-plants
-insects
-contactants
-exercise psychogenic
-IDIOPATHIC |
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|
Term
| What physiologically causes urticaria? |
|
Definition
| -mast cell and basophil degranulation |
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Term
| What are the clinical signs of urticaria? |
|
Definition
-multifocal wheals
-coalescine larger plaques
-linear or bizarre shaped patterns |
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|
Term
| How do we treat urticaria? |
|
Definition
-dexamethasone
-systematic removal of potential allergens: shampoos, sprays, stall bedding, feed, etc |
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Term
| What is the most common cause of allergic skin dz in the horse? |
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Definition
|
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Term
| What are the common names for insect hypersensitivity in the horse? |
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Definition
-Sweet itch
-Queensland itch
-Muck itch
-Summer dermatitis
-Allergic dermatitis |
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Term
| What two types of hypersensitivity reactions are seen with insect hypersensitivity? |
|
Definition
-type I hypersensitivity: immediate, response to antigens of biting insects, inc IgE in skin
-type IV hypersensitivity: delayed, cell-dependent immunological response to an Ag |
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Term
| What bugs are horses hypersensitive to? |
|
Definition
-gnats: Culicoides
-black flies: Simulium
-stable flies: STomoxyc salcitrans
-Horn fly: haematobia irritans
-Deer fly: chrysops |
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|
Term
| What is the most common cause of insect hypersensitivity in the horse? |
|
Definition
|
|
Term
| Certain horse breeds appear to have genetic predisposition to hypersensitivity reactions. What breeds would these be? |
|
Definition
-Welsh ponies
-Icelandics
-Arabians
-Connemaras
-German shires |
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|
Term
| What is the seasonality of insect hypersensititvity? |
|
Definition
|
|
Term
| What are the clinical signs of insect hypersensitivity? |
|
Definition
-pruritis
-dorsal distribution: from base of tail to face, crusted papules/ulcers, hair loss, lichenification, Culicoides, black flies
-Ventral distribution: ventral thorax and abdomen, axillae, legs, crusted papules, culicoides, horn flies, stableflies |
|
|
Term
| How do we diagnose insect hypersensitivity? |
|
Definition
-history
-physical exam
-rule out other conditions
-response to insect control |
|
|
Term
| What diagnostic tests do we use for insect hypersensitivity? |
|
Definition
-skin scrapins
-skin cytoloyg/cultures
-food trials |
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|
Term
| How do we manage insect hypersensitivity? |
|
Definition
-insect control
-enironmental changes: strong fans, eliminate standing water, clean manure
-residual insecticides
-fly predators |
|
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Term
| Which insects are an issue during daylight hours? |
|
Definition
| -horseflies, stable flies, black flies, horn flies |
|
|
Term
| Which insects are an issue during duck/dawn, night hours? |
|
Definition
| -culicoides spp, mosquitoes |
|
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Term
| How do we treat insect hypersensitivity? |
|
Definition
-systemic treatment in addition to fly control
-systemic antipruritic agents: glucocorticoids, antihistamines, omega-6/omega-3, combos
-glucocorticoids
-antihistamines |
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Term
| What are the possible etiologies of tail rubbing? |
|
Definition
-parasitic: oxyuris equi, Amblyomma americanum, mange
-fly bite hyeprsensitivity |
|
|
Term
| Are young or older horses more commonly affected by oxyuris equi? |
|
Definition
| -typicall younger horses under 3y but odler horses can be affected too |
|
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Term
| HOw do we test for oxyuris equi? |
|
Definition
|
|
Term
| What do we use to treat oxyuris equi? |
|
Definition
-anthelmentics: macrocyclic lactones, oxibendazole, fenbedazole, pyrantel pamoate
-mild detergent shampoo
-anti-puritic sprays |
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