Sweet itch is a debilitating, extremely irritating and often painful skin condition that is unfortunately very common, especially in native pony types, affecting around 5% of the overall horse population in the UK. It's caused by an allergic reaction to midge bites which then causes localised irritation to the skin, and is normally most prevalent along the mane, back and at the base of the tail. The reaction is caused by sensitivity to irritants within the midge's saliva which causes itchiness - in some cases extreme itchiness - which then leads horses to scratch, bite or rub at their skin in an attempt to relieve the discomfort. If left unmanaged, the repeated itching leads to bald patches and areas of sore or even broken and bleeding skin. Some horses can cause severe damage to themselves and their environment in their attempts to relieve itching, and in some occasions horses might not be able to tolerate tack.
Ponies generally tend to be more affected by sweet itch than horses, with certain breeds more prone than others. Native breeds such as Welsh Ponies, Shetlands, Connemaras and cob types seem to be more prone, with research showing that it could be genetic - foals from an affected stallion or mare are more likely to develop the condition.
Sweet itch suffers will show allergic reactions and itching between March and November, worsening in hot, humid weather and around dawn/dusk when more midges are around. The main symptom of this condition is the repeated itching in localised areas (usually along the mane, back and tail). This leads to the loss of mane and tail hair, bald patches on the body, sore and broken skin and the thickening of the skin due to repeated damage.