Changes

==History and clinical signs==

==History and clinical signs==

Multiple wheals are often observed and occur within a few minutes or hours of exposure to the causative agent. A history of recurrence or repeated episodes is often reported. Affected areas can vary from small, localised lesions up to 3cm in diameter, to extensive generalised areas involving large areas of skin. Lesions can occur on any part of the body but usually develop on the back, legs, flanks, neck and eyelids. Dermatographism is a specific pressure-induced type of urticaria in which wheals form in reponse to exogenous pressure, commonly these are observed in the saddle area of the horse. In severe cases the mucous membranes of the nose, mouth, anus and vulva may be involved.  Pruritus may or may not be present and the lesions usually disappear rapidly.

Multiple wheals are often observed and occur within a few minutes or hours of exposure to the causative agent. A history of recurrence or repeated episodes is often reported. Affected areas can vary from small, localised lesions up to 3 cm in diameter, to extensive generalised areas involving large areas of skin. Lesions can occur on any part of the body but usually develop on the back, legs, flanks, neck and eyelids. Dermatographism is a specific pressure-induced type of urticaria in which wheals form in reponse to exogenous pressure, commonly these are observed in the saddle area of the horse. In severe cases the mucous membranes of the nose, mouth, anus and vulva may be involved.  Pruritus may or may not be present and the lesions usually disappear rapidly.

==Diagnosis and treatment==

==Diagnosis and treatment==