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Also known as: '''''Summer sores — Granular dermatitis — Bursautee
==Introduction==
Cutaneous '''Habronemiasis''' is a hypersensitivity reaction to the larvae of the nematode species [[Habronema and Draschia spp.|''Habronema'' and ''Draschia'']].
The condition is characterised by '''ulcerative, granulomatous''' skin lesions which do not heal.
Cutaneous '''Habronemiasis''' is a hypersensitivity reaction to the larvae of the nematode species ''Habronema'' and ''Draschia''. The adult nematode lives in the stomach of the horse and produces eggs which are then passed in the faeces as larvae. The larvae are ingested by the house fly (''Musca domestica'') or stable fly (''Stomoxys calcitrans'') in their larval phase, and deposited on equine skin when they feed as adult flies.
The condition is characterised by ulcerative, granulomatous skin lesions which do not heal.
==Signalment==
==Signalment==
Lesions most commonly occur on the legs, ventrum, around the eyes, urethral process and prepuce and at the site of pre-existing wounds.
Lesions most commonly occur on the legs, ventrum, around the eyes, urethral process and prepuce and at the site of pre-existing wounds.
The lesions are single or multiple ulcerative nodules with a serosanguinous discharge. There may be excessive granulation tissue and small yellow granules of necrotic debris which surround the larvae.
The lesions are single or multiple ulcerative nodules with a serosanguinous discharge. There may be excessive granulation tissue and small yellow granules of necrotic debris which surround the larvae.
Pruritus may be mild to severe.
Pruritus may be mild to severe.
In cases of '''conjunctival habronemiasis''' there will be gitty plaques on the conjunctival and palpebral borders, which is painful in severe cases leading to epiphora and blephrospasm. Conjunctival habronemiasis is fairly common and must be differentiated from [[Squamous Cell Carcinoma|squamous cell carcinoma]] of the third eyelid.
===Cytology===
Cytology of the exudate or skin scrapings frequently reveal larvae but biopsy is recommended because ''Habronema'' larvae commonly invade skin lesions with another underlying cause such as infectious granulomas, [[Sarcoids|sarcoids]] and ulcerative dermatitis.
===Biopsy===
===Biopsy===
Biopsy will reveal nodular/diffuse granulomatous dermatitis with eosinophilic infiltrates and mast cells. Necrotic foci with multiple nematode larvae and granulation tissue with [[Neutrophils|neutrophils]] along the ulcerated surface are also characteristic.
==Treatment==
Systemic '''glucocorticoids''' decrease the inflammatory response of the the hypersensitivity reaction, e.g. oral prednisolone.
Organophosphate pastes and anti-inflammatory pastes can be applied to the wound until it has healed, or the wound should be bandaged to prevent reinfestation.
Excessive granulation tissue should be removed surgically.
The conjunctival form can be treated with topical ivermectin eye drops with a pH of 7.4.
Ivermectin or appropriate anthelmintics should be used to limit nematode infestation, fly control will also reduce exposure to the larvae.
Ivermectin or appropriate anthelmintics should be used to limit nematode infestation, fly control will also reduce exposure to the larvae.
==Prognosis==
==Prognosis==
Recurrence is common. Fly control, meticulus wound management and regular anthelmintic use is needed to prevent or limit the condition.
Recurrence is common. Fly control, meticulous wound management and regular anthelmintic use is needed to prevent or limit the condition.
<big>'''See also [[Spirurids - Donkey|Habronemiasis in Donkeys]]'''</big>
{{Learning
|literature search = [http://www.cabdirect.org/search.html?q=%28%28title%3A%28%22Cutaneous%22%29+AND+title%3A%28%22Habronemiasis%22%29%29+OR+title%3A%28%22Summer+sores%22%29+OR+title%3A%28%22Granular+dermatitis%22%29+OR+title%3A%28Bursautee%29%29+AND+od%3A%28horses%29 Cutaneous habronemiasis publications]
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==References==
==References==
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[[Category:To_Do_- lizzyk]]
[[Category:Expert_Review]]
[[Category:Dermatological Diseases - Horse]]
[[Category:Integumentary System - Helminth Infections]]