What is Equine Sweet Itch and how can you spot the symptoms, prevent it or treat it.

Equine Sweet Itch is a seasonal allergic skin condition caused by fly bites. The fly most commonly involved is Culicoides pulicaris midge and although most horses and ponies are bitten by this midge, they show no major signs or reaction to it. However, horses that suffer from sweet itch develop an allergy to the bites.

Sweet Itch, or Summer Seasonal Recurrent Dermatitis (SSRD), is a problem that affects thousands of horses, ponies and donkeys in many countries.

Almost all horse breeds and types of ponies can be affected, from tiny Shetland ponies to heavyweight draught horses, although the condition is rare in English Thoroughbreds.

In South Australia reports say that as many as 60% of horses and ponies are affected. About 5% of the UK horse population are thought to suffer.

Although known by different names (e.g. Sommer Ekzem in Germany, Kasen in Japan, Queensland Itch in Australia), sweet itch symptoms are always the same.

Equine Sweet Itch Symptoms

Sweet Itch symptoms include severe itching, hair loss, skin thickening and flaky dandruff. Exudative dermatitis , ie; weeping sores, sometimes with a yellow crust of dried serum, can occur. If sores are not attended to properly a secondary infection can result.

The top of the tail and the mane are most commonly affected. The neck, withers, hips, ears and forehead, and in more severe cases, the mid-line of the belly, the saddle area, the sides of the head, the sheath or udder and the legs.

Your horse 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 to rub on, your horse may scratch out their mane with their hind feet and bite vigorously at their own tail, flanks and heels. You may see your horse drag itself along the ground to scratch its belly or sit like a dog and propel themselves round to scratch the top of their tail.

There can be a marked change in temperament resulting in lethargy with frequent yawning and a general lack of spark, or your horse may become agitated, impatient and lack concentration when ridden. Your horse will become very agitated when flying insects are around and may start head shaking repeatedly.

Diagnosing Equine Sweet Itch

Diagnosis is not usually difficult as the symptoms and the seasonal nature (spring, summer and autumn) are strong indicators. However symptoms can persist well into the winter months, with severely affected horses hardly having any respite before the midge starts its onslaught again the following spring.

Horses that go on to develop equine 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. Sweet itch is most commonly seen in animals from 4 to 6 years of age as the allergy requires repeated exposure to fly bites to develop, this usually takes 2 to 4 summers. The signs of sweet itch can get worse as the animal gets older.

There is evidence that stress caused by moving to a new home, sickness, or severe injury, can be a factor when mature animals develop Sweet Itch.

Environmental factors play a major part and where the horse is born and where it lives as an adult are at least as significant as the bloodlines of its sire and dam.

Sweet Itch is not contagious, although if conditions are particularly favourable for a high Culicoides midge population, more than one horse in the field may show symptoms. The midge, Culicoides pulicaris, tends to stay near its breeding ground, wet areas, ponds, ditches, etc, and is most numerous when the weather is warm. They appear to be present more in the afternoon and through the warm evenings.

In the UK Sweet Itch is classed by Vets as a reportable condition, which must be disclosed by an owner to a prospective purchaser before the sale. A vet diagnosing the allergy may regard the condition as serious and specify your horse as unsound because of it.

Treating Equine Sweet Itch :

At present there is no cure for Equine Sweet Itch. Once an animal develops the allergy it generally faces a life-sentence and every spring, summer and autumn becomes a distressing period for both the horse and the owner.

Your horses comfort and well being are down to you, its owner, and the only reliable treatment available at the moment is to prevent the midges biting your horse.

The condition is incredibly frustrating to manage, however, it can be made easier providing you, the owner, take the time to understand the exact nature of your horses problem.

Stabling:
Stable your horse during peak fly periods and only turn-out when fly numbers are low. Stable at dusk and dawn, when midge feeding is at its peak, and close stable doors and windows, midges can get into warm stables. The installation of a large ceiling mounted fan can help create less favourable conditions for the midge.

For slight to moderate cases of Sweet Itch this can help. However a seriously itchy, stabled horse has hours of boredom to think up new ways of relieving his itch. Manes and tails can be demolished in a few hours of scratching against a stable wall. If stabling can be avoided it is best to do so.

Turning Out:
Avoid marshy, boggy fields. If possible move your horse to a more exposed, windy site, A bare hillside or a coastal site with strong onshore breezes. Chalk-based grassland will have fewer midges than heavy clay pasture.

Ensure your paddock is well drained and well away from rotting vegetation. Stay away from the muck heap, old hay-feeding areas, compost and rotting leaves.

Using electric fencing to prevent your horse from rubbing can help prevent skin damage, but it does not treat or prevent the underlying problem developing.

Barriers, Summer Sheets and Hoods
Use summer sheets and hoods that act as a barrier to prevent the midges biting.

Use a Boett® veterinary blanket. This is by far the most effective Sweet Itch protection to date and avoids the need to use insecticides, oils or greases. The Boett, pronounced Bo-ett, Blanket was invented in Sweden seventeen years ago to offer protection to horses and ponies suffering from insect-bite allergy.

It has been continually developed since then and is now used around the World as the best way to manage Sweet Itch, while avoiding undesirable side effects.

Deterrents, Fly Repellents, Insecticides, Oils and Greases
Use fly repellents, there are many fly repellents available including those containing benzyl benzoate, permethrin, garlic or citronella. Fly repellents containing diethyl toluamide (DEET) are the most effective. Make sure you try a small amount of any new repellent on a small area of your horses skin to test for any reaction.

DEET (the acronym for N,N-Diethyl-m-toluamide), has a track record stretching back over 40 years and has proven to be highly effective. It is the active ingredient in many midge and mosquito repellents used by humans. Research has shown that the higher the concentration of DEET in a repellent the more effective and long-lasting it is likely to be.

Benzyl benzoate was originally used to treat itch-mites (scabies) in humans and has been used for many years to combat Sweet Itch. In its neat form it is a transparent liquid with an aromatic smell, but it is more commonly obtained from Vets or pharmacies as a diluted milky-white suspension. It is listed as an ingredient in several proprietary formulations, including Carr, Day & Martins Kill Itch and Pettifers Sweet Itch Plus.

Benzyl benzoate should be thoroughly worked into the skin in the susceptible areas every day. However it is a skin irritant and should not be used on the horse if hair loss or broken skin have occurred. Application should start before symptoms develop in the spring. If used later its irritant properties can cause areas of skin to slough-off, in the form of large dandruff type flakes.

Some owners achieve good results with insecticides whilst others find they have shown little benefit in controlling Sweet Itch.

Always wear gloves when applying insecticides, including benzyl benzoate. Particular care should be taken if they are used on ponies handled by children as they can cause eye irritation. Especially if there is any risk that little fingers may transfer the chemical from the pony's mane to the eyes.

Coat the susceptible areas of your horse with an oil.
Midges dislike contact with oil and they will tend to avoid it. Commonly used preparations include Medicinal Liquid Paraffin and Avon Skin-so-Soft bath oil (diluted with water). There are several oil-based proprietary formulations, for example Day Son & Hewitt's Sweet Itch Lotion.

You can also try the Olive Oil and Garlic remedy outlined on Debbies equestrian tips page.

Oils and other repellents that are effective usually work for a limited time. In summer your horses short coat doesn't retain the active ingredient for long and it can be easily lost through sweating or rain. You usually have to re-apply two or three times every day.

Greases (usually based on mineral oils) stay on the coat longer, but they are messy and therefore not ideal if the horse is to be ridden. They can be effective if only a small area of the horse is to be covered. However it is impractical and often expensive to cover larger areas.

Some preparations contain substances like eucalyptus oil, citronella oil, tea tree oil, mineral oil or chemical repellents that can cause an allergic skin reaction themselves. Always patch test first, on your horses neck or flank and leave for 24 hours before using fully.

Medicines, Steriods, anti-histamines
Depressing your horse immune system with corticosteroids, either by injection of Depo-Medrone or Kenalog, or using Prednisolone tablets may bring temporary relief but there can be side effects, including laminitis. Corticosteroids can also become less effective over prolonged use, requiring larger and more frequent doses for the same level of relief.

The use of anti-histamines may bring some relief but high dose rates are required and they can make your horse drowsy.

Applying soothing lotions or creams to irritated areas such as Calamine lotion or Sudocrem can bring relief and reduce inflammation, but they will not prevent midge attack.

Steroid creams can reduce inflammation.

Effective treament of equine sweet itch depends on the severity of your horses condition and how much time and money you can afford to spend on it. You, the owner, are the only person that can decide your best and most cost effective treatment.

Reducing exposure to the Culicoides pulicaris midge is by far the best way to go, but locking your horse in a hot stable all summer could make life unbearable and we don't all have access to a windy, chalky hillside paddock.

No, equine sweet itch is one condition that requires you, the horse owner, to think about your horses care before diving in and trying forty different creams, lotions, rugs, repellents or drugs.

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