What is Sweet Itch?

Sweet itch is an allergic reaction to bites from mosquitos and midges which can affect almost any horse or pony – regardless of type, breed and age – but research does show it is particularly prevalent in some native breeds. Sweet itch is the most common allergic skin disease in the UK and affects around five per cent of our horse population.

The types of midges and mosquitos which cause the hypersensitivity differ depending on the country but in the UK these are the black fly (Simulium) and the midge (Culicoides). It is also worth noting that whilst we tend to think of sweet itch as a summer condition, these biting insects are active from March to November. The itchiness associated with insect bite allergies can be termed pruritis and the term ‘sweet itch’ literally describes the sensation experienced by the horse or pony in reaction to the bites. The condition varies in severity from the horse occasionally scratching his tail on a tree to the very worst cases who will scratch and scratch, causing self-trauma. A lot of cases will also have secondary infections or other allergens involved.