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42 2. Immunological: hypersensitivity where antigen/allergen probably reaches the skin via the systemic route rather than by local contact. The antigen reaches the systemic circulation mechanisms involved include type 1 and 111 hypersensivity reactions • Injection (drugs such as some antibiotics, BTZ, Ivermectin, Moxidexin, pethidine, Vit B complex, flunixen, iron dextran and many others) • Ingestion (chemical, feeds pasture plants) • Inhalation (pollen, dust, chemicals, moulds) • Vaccines (strangles, botulism, salmonella, tetanus etc) • Transfusion reactions • Biting insects (biting flies, mosquitoes, blackflies,bees, wasps, spiders etc) • Infections (bacterial, fungal, viral parasites such as onchocerciasis, habronemiasis,) • Vasculitis (streps, purpura haemorrhagica) 3. Allergic urticaria: • Atopy • Drug related • Food allergy • Inhaled antigens, pollens, moulds • Contact allergy (very rare); must be carefully distinguished from allergic contact dermatitis. 4. Physical urticaria, non-immunological pathogenesis. • Dermatographism: wheal developing from blunt scratch on skin • Cold urticaria, heat and light • Exercise induced urticaria Clinical Presentation There is no breed, age or sex predilection. Onset can be peracute to acute with signs developing within minutes up to a few hours and usually resolve in 24-48 hours occasional signs can last up to 6-8 weeks. Or in the instance of recurrent urticaria it may be chronic or persistent if present for more than 8 weeks Lesions An oedematous lesion of the skin or mucous membrane is called a wheal, which is a flat topped papule/nodule with steep walled sides which pits on pressure. Some have slightly depressed centres. ACVSC Proceedings Dermatology Chapter Science Week 2005
Wheals vary in size and shape and quite arbitrarily may be divided into: 1. Conventional: 2-3mm up to 3-5mm. 2. Papular: multiple small uniform 3-6mm diameter wheals i.e. insect bites. 3. Giant: either single or coalesced multiple wheals up to 20-30cm diameter. 4. Annular: donut like lesions. The lesion may present differently depending on the location of the oedema i.e. whether it is in the upper layers of the dermis or subcutaneous and may be pruritic or non pruritic. 1. "Oozing urticaria" - where dermal oedema is severe, oozing of serum from the skin surface may occur. Care should be taken to distinguish this from an erosive/ulcerative process or a pyoderma. NB lesion must still pit on pressure. 2. Gyrate urticaria - has been referred to as the dermal form of erythema multiforme but it should be stressed that this syndrome is not related to 'true' erythema multiforme which is primarily an epidermal disease (lesions DO NOT pit on pressure). Drug reactions appear to be the most common cause of this form of urticaria. 3. Angiooedema (Angioneurotic oedema) - a subcutaneous form of urticaria which tends to be more diffuse due to lack of restraint to spread in the sub cutis. Usually involves the head and extremities and is more indicative of a systemic and serious disease than urticaria. Diagnosis Because of the numerous potential causes of urticaria a definitive diagnosis may only be reached after extensive clinical and diagnostic investigation which can be time consuming, expensive and often unrewarding. Horse owners usually are reluctant to undertake the costly task of endeavouring to obtain an accurate diagnosis. Initially, diagnosis is mostly based on clinical signs (mostly cutaneous reaction patterns) and a careful history of the case. (Scott & Miller 2003) History is important: - Is it the first attack? - If not, how many and are they seasonal? - Site of lesions- is it a point of contact with gear? - Use of any drugs, frequency and reaction at time of use, drenches, medicated sprays, ointments, shampoos, ultrasound gel. Etc - Pasture plants Specific activities-exercise only induced Being worked, (confirm by 30 min exercise producing urticaria) out in paddock for pick of grass - Food allergy can only be traced by elimination diets and then challenge with suspected feed ( very time consuming with NO short ACVSC Proceedings Dermatology Chapter Science Week 2005 43
Page 1 and 2: Australian College of Veterinary Sc
Page 3 and 4: Australian College of Veterinary Sc
Page 5 and 6: 3.00 Afternoon tea 3.30 How I treat
Page 7 and 8: Dr Jennifer A. Charles BVSc MVS Dip
Page 9 and 10: Scientists in Feline Medicine in 19
Page 11 and 12: IgE-bearing cells have been demonst
Page 13 and 14: years, median age 6.5 years, with a
Page 15 and 16: dusts, grain smuts, moulds, danders
Page 17 and 18: References: Evans AG, Paradis MR, &
Page 19 and 20: Comparatively simple, cheap and eff
Page 21 and 22: TABLE 1: CURRENT ALLERGENS SELECTED
Page 23 and 24: AmericanCockroach Cockroach mix
Page 25 and 26: Patient Preparation Drug Withdrawal
Page 27 and 28: Each injection site is visually exa
Page 29 and 30: References 1. Scott DW, Miller WH:
Page 31 and 32: Intradermal Testing (IDT) in Horses
Page 33 and 34: TABLE 2 Additional allergens used i
Page 35 and 36: Allergen Positive reactions Mosquit
Page 37 and 38: much higher and corresponded to the
Page 39 and 40: and this and other uncontrolled tri
Page 41: Introduction Diagnostic Approach to
Page 45 and 46: References Evans AG, Paradis MR & O
Page 47 and 48: Introduction: Equine Chronic Urtica
Page 49 and 50: Acute treatment - Epinephrine 1:100
Page 51 and 52: anecdotal success with use of human
Page 53 and 54: an 80:20 mixture of evening primros
Page 55 and 56: Clinical approach to the horse with
Page 57 and 58: identify plants in a pasture that m
Page 59 and 60: Equine sarcoidosis Sonya Bettenay T
Page 61 and 62: described as a possible feature of
Page 63 and 64: others 2001), isotretinoin(Waldinge
Page 65 and 66: 12. LeGall, F., Loeuillet, L., Dela
Page 67 and 68: Introduction The equine sarcoid: an
Page 69 and 70: Clinical Presentation Small fibrous
Page 71 and 72: Assessment should be made on the fo
Page 73 and 74: (ix)Bone becomes devitalized if inc
Page 75 and 76: and mitomycin C have been used. All
Page 77 and 78: Owen LN & Barnett KC (1983) - Treat
Page 79 and 80: any anatomic location but commonly
Page 81 and 82: epidermis may be histologically nor
Page 83 and 84: References D.C. Knottenbelt, S. Edw
Page 85 and 86: indicated. Each sample for culture
Page 87 and 88: Proper dosage and proper duration a
Page 89 and 90: 2. Affect on the horse and 3. Affec
Page 91 and 92: Affected horses usually scratch and
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• Cattle ear tags impregnated wit
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How I treat: equine pemphigus folia
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Treatment of pemphigus foliaceus in
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SCOTT, D.W., WALON, D.K., SLATER, M
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Diagnosis History of access of hors
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These vaccines are not manufactured
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References Alfaro AA & Mendoza L (1
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y a variety of fungal metabolites.
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Authors recommendations: 1. Both Im
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chorioptic mange by the author (Lit
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Clinical Disease The clinical resul
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treatment options have been used. P
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Notes ACVSC Proceedings Dermatology
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