Changes

==Signalment & risk factors==

==Signalment & risk factors==

Although sweet itch may occur in horses of all breeds and ages, the disease has a peak age of onset of between 2 and 4 years. In cases where horses have been moved to an area with a heavier insect burden clinical signs may develop in older horses. Most breeds are affected although sweet itch is rare in Thoroughbreds. It has suggested that genetic factors may have a role in the pathogenesis of the disease as the prevalence of sweet itch in some breeds is higher, such as Icelandic ponies and German Shire horses.  

Although sweet itch may occur in horses of all breeds and ages, the disease has a peak age of onset of between 2 and 4 years. Clinical signs may develop in older horses if moved to pasture area with a heavier insect burden. Most breeds are affected although sweet itch is rare in Thoroughbreds. It has suggested that genetic factors may have a role in the pathogenesis of the disease as the prevalence of sweet itch in some breeds is higher, such as Icelandic ponies and German Shire horses.  

''Culicoides'' require marshy areas or still water and horses kept in fields near streams or water may be at higher risk of developing sweet itch. Additionally, in order to breed successfully the midges require decaying manure and bedding, therefore poor hygiene increases the risk of sweet itch.   

''Culicoides'' inhabit marshy areas or still water and horses kept in fields near streams or water may be at higher risk of developing sweet itch. Additionally, in order to breed successfully the midges require decaying manure and bedding, therefore poor hygiene increases the risk of sweet itch.   

==Pathogenesis==

==Pathogenesis==