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Summer or Sweet Itch in Horses

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Introduction to Sweet Itch or Summer Itch:

Sweet itch or summer sores can make the summer months miserable for horse and horse owner. It is not unusual for sweet or summer itch to reoccur each year, as the biting insect responsible for the itch returns with warmer temperatures. Often it will be the same area on the horse that is affected. Sometimes sweet or summer itch is called hot spots because the inflammation causes discernible heat to radiate from the affected area. This is not exactly the same as hotspots on dogs however. I have seen a horse that was affected each summer, in the same area, with an inflamed area the size of an outstretched hand. In the fall, the sore area subsided and disappeared.

Names:

Summer Itch, Sweet Itch, Summer Sores, Hot Spots, Summer Seasonal Recurrent Dermatitis, Allergic Dermatitis, Queensland Itch

Causes:

Sweet itch or summer itch is blamed on biting insects . The horse will have an allergic reaction to insect bites that cause intense inflammation and itching. It is usually midge bites, also called no-see-ums, sand flies or punkies, that the horse is sensitive to. Generally, mosquitoes and black flies will not cause summer itch, but there is always an exception. When we lived in an area with bad black flies, the bites would cause bands of scabby, itchy areas across the horses chests and stomachs. As soon as the insects went away, the areas healed, and there was no sign of an allergic reaction. The insects responsible for summer or sweet itch usually bite along the top line and down towards the base of the tail, although depending on the type of insects, the abdominal mid-line may be affected.

Symptoms:

After being bitten by insects, the horse shows an allergic reaction to the bug's saliva on its skin. Patches of the horse's coat may stare and the area will be inflamed. The horse may kick or bite at, or try to rub the area.

Effects:

The areas may become hot to the touch, and look red and weepy. The hair, which may be standing straight up, may eventually fall out leaving bald patches. The inflamed area will probably be painful, or intensely itchy and the horse will object to any pressure on the area. If the area is very itchy the horse can cause further damage to itself by rubbing on trees, fences or stall walls. There is also a chance that the area could become infected. The same horse will often be affected in the same area of their body year after year. As the insects disappear in the autumn, the allergic reaction will also subside and eventually disappear. The hair, as long as the horse has not badly damaged the area by rubbing, should regrow.

Treatment:

Because it is often difficult to pinpoint exactly what is causing the allergic reaction, you may need a veterinarian to help determine if it is biting insects or something else that your horse is reacting to. Your veterinarian may suggest you apply a topical medication that contains corticosteroids to reduce the inflammation. This will only help relieve some of the itchiness and pain, but it will not help with the cause. Soothing washes of aloe vera, calendula or other herbal preparations may help calm inflamed and itchy areas.

Prevention:

To fully avoid sweet itch, the insect sensitive horse will have to be completely protected from whatever insect is causing the problem. This might include putting fly spray and fly sheets and masks on the horse as in the example of Bramble, a reader's horse who has reoccurring Sweet Itch, keeping it stabled during the insects active time or removing the horse from the location altogether. Sweet itch, unlike skin problems like ringworm and mange, is not transmissible through brushes, tack or handling. Owners dealing with sweet itch may also want to look into immune boosting supplements and homeopathic remedies and discuss the use of antihistamines with their veterinarian.

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