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==Introduction==

Cutaneous '''Habronemiasis''' is a hypersensitivity reaction to the larvae of the nematode species [[Habronema and Draschia spp.|''Habronema'' and ''Draschia'']].  

 

 

==Description==

Cutaneous '''Habronemiasis''' is a hypersensitivity reaction to the larvae of the nematode species [[Habronema and Draschia spp.|''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 [[Musca spp.|house fly]] (''Musca domestica'') or [[Stomoxys calcitrans|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.

The condition is characterised by '''ulcerative, granulomatous''' skin lesions which do not heal.

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 of the third eyelid.  

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.  

 

===Biopsy===

===Biopsy===

Biopsy will reveal nodular/diffuse granulomatous dermatitis with eosinophilic infiltrates and mast cells. Necrotic foci with multiple nemotode larvae, and granulation tissue with [[Neutrophils|neutrophils]] along the ulcerated surface are also characteristic.

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==

==Treatment==

Systemic '''glucocorticoids''' decrease the inflammatory response of the the hypersensitivity reaction, oral prednisolone is effective at a dose of 1mg/kg SID or BID for 14days and then tapered.

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.  

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.

Excessive granulation tissue should be removed surgically.

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.

 

 

 

==References==

==References==

*Rose, R. J. and Hodgson, D. R. (2000) '''Manual of Equine Practice''' (Second Edition) Sauders.

*Rose, R. J. and Hodgson, D. R. (2000) '''Manual of Equine Practice''' (Second Edition) Sauders.

[[Category:To_Do_- lizzyk]]

 

 

[[Category:Expert_Review]]

[[Category:Integumentary System - Helminth Infections]]