Symptoms
Sweet Itch, or Summer Seasonal Recurrent Dermatitis (SSRD), is a problem that affects thousands of horses, ponies and donkeys in many countries of the world to a greater or lesser degree. Virtually all breeds and types of ponies and breeds can be affected.

Symptoms include severe pruritus (itching), hair loss, skin thickening and flaky dandruff. Exudative dermatitis (weeping sores, sometimes with a yellow crust of dried serum) may occur. Without attention sores can suffer secondary infection.

The top of the tail and the mane are most commonly affected. The mid-line of the belly, the saddle area, the sides of the head, the sheath or udder and the legs may also suffer.

The animal may swish its tail vigorously, roll frequently and attempt to scratch on anything within reach. It may pace endlessly and seek excessive mutual grooming from field companions. When kept behind electric fencing with nothing on which to rub, sufferers may scratch out their mane with their hind feet and bite vigorously at their own tail, flanks and heels. They may drag themselves along the ground to scratch their belly or sit like a dog and propel themselves round to scratch the top of their tail on the ground.

There can be a marked change in temperament - lethargy with frequent yawning and general lack of 'sparkle' may occur, or the horse may become agitated, impatient and, when ridden, lack concentration. When flying insects are around, the horse may become agitated, with repeated head shaking.

Diagnosis is not usually difficult - the symptoms and its seasonal nature (spring, summer and autumn) are strong indicators. However symptoms can persist well into the winter months, with severely affected cases barely having cleared up before the onslaught starts again the following spring.

Horses that go on to develop Sweet Itch usually show signs of the disease between the ages of one and five and it is common for the symptoms to appear first in the autumn.

There is anecdotal evidence that stress (e.g. moving to a new home, sickness, or severe injury) can be a factor when mature animals develop Sweet Itch.

Sweet Itch is not contagious, although if conditions are particularly favourable to a high Culicoides midge population, more than one horse in the field may show symptoms.

Causes
Sweet Itch is an allergic reaction and therefore an immune system problem. Unfortunately these are notoriously complicated and difficult to deal with.

The disease is a delayed hypersensitivity to insect bites and results from an over-vigorous response by the animal's immune system. In the process of repelling invading insect saliva (which actually contains harmless protein) the horse attacks some of its own skin cells 'by mistake' and the resulting cell damage causes the symptoms described as Sweet Itch.

Treatment
At present there is no cure for Sweet Itch. Once an animal develops the allergy it generally faces a 'life-sentence'.
The animal's comfort and well being are down to its owner's management.

Treatment mainly consists of trying to minimise midge attack.

• Avoid marshy, boggy fields. If possible move the horse to a more exposed, windy site, e.g. a bare hillside or a coastal site with strong onshore breezes. Chalk-based grassland will have fewer midges than heavy clay pasture.
• Ensure pasture is well drained and away from rotting vegetation. (e.g. muck heaps, old hay-feeding areas, rotting leaves).
• Use a Sweet Itch Blanket. (See Links) This is by far the most effective Sweet Itch protection to date and avoids the need to use insecticides, oils or greases. The blanket covers the horse's body almost completely, thus preventing it from getting bitten.
• Use and insect repellant. Some are effective against flies but their effectiveness against Cullicoides is unproven.
• Coat the susceptible areas of the horse with an oil. Midges dislike contact with a film of oil and they will tend to avoid it.
  Oils and other repellants that are effective usually work for a limited time. Re-application two or three times every day may be neccessary. Greases (usually based on mineral oils) stay on the coat longer, but they are messy.
  Some preparations contain substances that can cause an allergic skin reaction. Always patch test first.

A less favourable alternative is to allow midge attack, but to try and minimize the resultant allergic reaction.

• As a final resort it is possible to suppress the immune system with corticosteroids. This may bring temporarily relief but there can be side effects, including laminitis, in some animals. With time, corticosteroids may become less effective, requiring ever larger and more frequent doses.
• Applying soothing lotions to the irritated areas. Soothing creams can bring relief and reduce inflammation, but they will not deter further midge attack. Steroid creams can reduce inflammation.

Info from: www.sweetitch.com