Equine Derm 2 Flashcards
Weeping and seeping
Most dermatosis
- accumulation of fluid exudate which is 2nd to skin damage
Ulcerative lyphangitis
Caused by corynebacterium pseudotuberculosis
SUDDEN onset swelling of lower limbs (hind)
MULTI draining sores, follow lymph distribution
Tx of ulcerative lymphangitis
Antimicrobials therapy
- penicillin + aminoglycosides or floroquinolones
NSAIDS
Hydrotherapy
Bandaging to decrease edema
Pastern dermatitis
Scratches or greasy heel
Dermatitis of heel & caudal pastern
Common but not specific disease entity
Scratchy etiology
Chronic irritation of caudal pastern and heel
May be complicated by self-trauma
Infectious organisms often involved
Scratches Pathophys
Constantly exposed to irritation/injury, moisture and caustic substances
• Irritated skin allows for colonization by bacteria, fungi
• Infection —>worsened inflammation (pain, swelling) ±
exudation ± crusting, alopecia =constant flexion may lead to fissure formation
• Pediculosis and acariasis may predispose to/initiate this process
Clinical signs of scratches
Lesions may develop in one or more limbs
May involve only unpigmented skin initially
Acute lesions begin at heels then spread proximally and
anteriorly
Skin becomes thickened and may develop fissures - tightening of skin
DX and differentials of scratches
Diagnosis:
Any case involving only unpigmented skin must be evaluated for hepatic disease!!
Impression smears, fungal cultures, groomings and skin scrapings should be done in all cases
Differentials:
Contact dermatitis, chorioptic mange, photosensitization, vasculitis, sarcoid
Treating scratches
Treat predisposing problem - damage: mechanical, chemical, hair
Clean w 2% chlorhexidine scrub
Topical GC’s
- gentocin spray
Nodules
Common finding in many derm conditions
Inflammation: infectious, allergy, sterile
Non inflame: cysts, hernias
Neoplastic
Nodular necrobiosis
MOST common nodular skin condition ***
Firm, painless subQ nodules
DX by history & clin signs: biopsy definitive XX necessary
Treat w intralesional or systemic steroids
Neoplasia differentials
Sarcoid
Squamous cell carcinoma
Melanoma
Sarcoid
MOST common tumor of horses 90%
Found in young/YA horses
Head and ears
Locally invasive but nonmalignant - BPV?
Progression of sarcoids
Occult: flat, dry
Verrucous: wart like
Nodular: no skin eruption
Fibrous: looks like proliferative granulation tissue
Malignant or malevolent sarcoid
AGGRESSIVE & locally invasive
Multiple tumor types in one individual
SCC
Locally invasive, slow to metastasize
Common in Appaloosa, light colored breeds, YA <5y
-Non healing ulcerations
-nonpigmented skin - MCc junctions
-cauliflower lesions, bleeding
Risk and prog for SCC
Chronic UV exposure
Infection w equine caballus papilloma virus-2
Early recognition and Tx improves prognosis
Good when complete excision is possible or lesion is superficial
Melanomas
Second most common dermal tumor in EQ 80%
Majority benign at first but 66% can become malignant if untreated
Malignancy more common in NON gray horses
Treating neoplasia
Benign neglect
Surgery
Radiotherapy
Chemo therapy
Electro therapy
Photodynamic therapy
Antiviral therapy (sarcoid)
Immunomodulators therapy (sarcoid, melanoma)
Topical Tx
Papillomatosis
Warts due to EQPV
Common in young 6m-4y
Transmitted by black flies
No treatment - autogenous vaccines ?
Aural plaques
Lesions on pinnae associated with EQPV3,4,5,6
Flat HK proliferative area on inner surface of pinna
DX based on characteristic appearence
WILL NOT spontaneously regress
Tx of aural plaques
??
Imiquimod cream - immune response mod
Ivermectin, Cisplatin, eletrochemotherapy
Anhidrosis
Temp or total loss of ability to sweat, leads to
Exercise intolerance
Prolongation of recovery time
Poor quality of life
Dry flaky alopecia skin
Temporary anhidrosis
Can occur from overtraining or electrolyte imbalance
Drug associated
- macrolides (erythro worse that azithro or clarithromycin)
- antihistamines
Chronic idiopathic anhidrosis
Occurs in more than ONE consecutive summer season, will not resolve despite changes in housing, diet, exercise
Genetic?
Treating anhidrosis
Avoid hyperthermia !! Shade, rest, water
Electrolyte supplementation
Nutritional supplements
Antiinfectives
Antibacterials
Antifungals
Antivirals
Antiseptics/disinfectants
Ectoparasiticides
Anthelmintics
Antibacterials
C/S is ideal
Spectrum: gram positives often in skin
Good first choice:
Penicillins
TMS
Doxycycline
7-10 days minimum treatment
Challenges with antibacterials
Improved gram neg coverage: gentamicin
Highly lipophilic drugs:
Enrofloxacin
Chloramphenicol
Rifampin - good for staph, DO NOT USE ALONE
Systemic antifungals
Only for difficult lesions
- sodium or potassium iodide
- Amphotericin B
- griseofulvin
- azole drugs
Topical antifungals
Chlorhexidine
Povidone iodine
Miconazole crams
Lime sulfur dips
Enilconazole dips
Diluted bleach for environment
Therapeutics for ectoparasites
Ectoparasiticides
- organophosphates
- pyrethrins
- lime sulfur
- avermectins
Anthelmintics
- avermectins
- pyrantel pamoate/tartrate
- fenbendazole
Antihistamines
Little derm effect
- hydroxyzine hydrochloride
- Chlorpheniramine
- diphenhydramine
Hyposensitization
Allergen specific immunotherapy (ASIT)
Varying success, poor DX or prognosis
Discontinue after 6 months if no response
GC’s
Can alter pathologic processes
Anti inflammatory
Immunosuppressive
Use of GC’s for anti inflame
Nodular necrobiosis
Pastern dermatitis
Various …
Use of GC’s for immunosuppressive Tx
Pemphigus foliaceus
Hypersensitivity reactions
GC drugs
Prednisone
Prednisolone
Dexamethasone
Triamcinolone
Gentamicin
Prednisolone
Oral, intralesional, IV, IV topical
More $$
Absorption approved more than prednisoneXX
Delivered as active form
Dexamethasone
IV, IM, topical
More potent, longer half life
Risk of laminitis***
Triamcinolone
Intralesional inj, topical
Extremely potent
Lower risk of laminitis
GC that can be admin intralesionally
Prednisolone
Triamcinolone
GC in order of potency
Least —> most
PrednisoneXX
Gentocin spray
Prednisolone
Dexamethasone
Triamcinolone
Use of apoquel in horses
Inhibition of Janus kinase dep cytokines involved in allergy & inflammation & pruritis
Can be used for Culicoides hypersensitivity
