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Introduction 100 How I treat: equine phycomycosis ACVSC Proceedings Dermatology Chapter Science Week 2005 Reg Pascoe Chronic, subcutaneous, fungal, ulcerative, granulomatous, subtropical and tropical skin disease caused by Pythium insidiosum. Affects horses of all breeds, ages and sexes. Most cases occur in summer and autumn Other names include Bursatee, Florida horse leech, Swamp cancer.(Bridges & Emmons 1961, Blackford 1984 Scott & Miller 2003) Aetiology / Pathophysiology Caused by Pythium spp., free-living aquatic organisms which are not true fungi. Horses become infected by standing for long periods in stagnant water with rotting organic material and high ambient temperatures. 30º C to 40º C favour infection. Damaged skin assists the entry of the organisms into the horse’s skin Clinical Presentation There is no age, sex or breed predeliction. Pruritus occurs early in the infection with biting and kicking at affected area with subsequent ulceration of skin or wound Most lesions occur on legs and lower abdomen and chest. Lesions are usually single and unilateral but occasionally are multiple. Body lesions are often roughly circular with a sticky, serosanguineous, stringy discharge which either mats hairs or hangs from body wall in thick mucopurulent strands. Numerous irregular, gritty,coral like bodies (kunkers) occur within the necrotic sinuses found in the lesion. These are composed of fungal hyphae and tissue debris. Involvement of joint and tendons with sinus formation is a serious complication. Bone involvement is seldom seen in lesions less than four weeks old. Chronically affected horses may show invasion of underlying bone commonest areas are the cannon bones sesamoids and phalanges Lymphadenopathy occurs in chronic cases Differential diagnosis Sarcoid, habronema infestation in wounds, neoplasms (especially sarcoids and squamous cell carcinomas), Mycetoma, Botryomycosis, excess granulation tissue, foreign body granulomas and other Zygomycetes.
Diagnosis History of access of horses to water-logged pasture or lagoon creeks, or inescapable rain flooded paddocks. Clinical signs of pruritus with serosanguineous stringy discharge is almost pathognomonic. Biopsy early lesions; send fresh sample for culture and culture immediately on selective media such as Campy blood agar or on Sabouraud's dextrose agar (if being transported for over 1 to 3 days, samples are better transported on ice packs and cultured on non-selective blood agar) (Grooters et al 2002). Histopathology Cytological examination of aspirates and direct smears shows granulomatous and pyogranulomatous inflammation with possible eosinophils. Fungal elements are often found in foci of necrotic material (kunkers) , Such findings are not definitive due to the similarity to the hyphae of Basidiobolus haptosporus and Conidiobolus coronatus Management There are no reported cases of spontaneous remission with pythiosis. Surgical excision of the tumour is the most common and successful method, particularly in the more chronic cases. As the surgery can be both extensive and time consuming, general anaesthesia is usually preferred (Bridges & Emmons 1961, Bridges 1972, Restrepo et al 1980). Surgery on leg lesions is considerably aided if tourniquets are used above the surgical area. Careful dissection over tendon and joint locations is important and in some cases, close application of tumour to joint capsule and tendon sheath makes the surgical approach extremely difficult. Due to the extensive nature of the draining holes and sinus, the skin edges often cannot be closed. Strong iodine is packed into the surgical area and pressure bandages are applied to the lesion. These are left in situ for 2-3 days, and once granulation has commenced, the wound can be left unbandaged. Local application of strong iodine (10%) may have some beneficial effect. Repeat surgery is more usual than not when the lesions occur around tendons and joints. Intravenous medication with sodium iodide, 1g/15kg b.w. twice at weekly intervals (Pascoe 1973) is a useful adjunct to surgery, and also aids in the reduction of some abdominal growths of excessive size. Amphotericin B was used both systemically and topically (McMullan et al 1977). Intravenous treatment was well tolerated at an average daily dose starting at 0.38 mg/kg and increasing to as high as 1.47 mg/kg. ACVSC Proceedings Dermatology Chapter Science Week 2005 101
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Australian College of Veterinary Sc
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Australian College of Veterinary Sc
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3.00 Afternoon tea 3.30 How I treat
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Dr Jennifer A. Charles BVSc MVS Dip
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Scientists in Feline Medicine in 19
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IgE-bearing cells have been demonst
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years, median age 6.5 years, with a
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dusts, grain smuts, moulds, danders
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References: Evans AG, Paradis MR, &
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Comparatively simple, cheap and eff
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TABLE 1: CURRENT ALLERGENS SELECTED
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AmericanCockroach Cockroach mix
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Patient Preparation Drug Withdrawal
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Each injection site is visually exa
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References 1. Scott DW, Miller WH:
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Intradermal Testing (IDT) in Horses
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TABLE 2 Additional allergens used i
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Allergen Positive reactions Mosquit
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much higher and corresponded to the
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and this and other uncontrolled tri
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Introduction Diagnostic Approach to
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Wheals vary in size and shape and q
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References Evans AG, Paradis MR & O
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Introduction: Equine Chronic Urtica
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Page 59 and 60: Equine sarcoidosis Sonya Bettenay T
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Page 67 and 68: Introduction The equine sarcoid: an
Page 69 and 70: Clinical Presentation Small fibrous
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Page 83 and 84: References D.C. Knottenbelt, S. Edw
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Page 105 and 106: References Alfaro AA & Mendoza L (1
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Page 117 and 118: Notes ACVSC Proceedings Dermatology
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