Sweet Itch in Horses: Signs & Symptoms and How to Treat Them | Help & Advice | Houghton Country

Sweet itch, or Culicoides Hypersensitivity, is an irritating condition whereby the horse becomes very itchy due to an allergic reaction to midge bites, and so will bite, scratch or rub their own skin sometimes to the point of inflicting damage to themselves and their surroundings. Affected horses are allergic to midge saliva, so when a midge bites the affected horse, the horse suffers an allergic reaction which presents as the skin becoming very itchy. Midges are most active in the summer months, so horses that suffer from sweet itch tend to show signs between March and October. This guide describes the main signs and symptoms of sweet itch in horses, and how best to treat them and manage the condition.

Native types and ponies are generally most susceptible to sweet itch. It is often seen in Welsh ponies, Connemaras, Shetland ponies and Icelandic ponies, for example, but can occur in any breed, including Thoroughbreds and Warmbloods too. It is believed to be genetic, with either the mare or stallion – or both – passing it on to the foal. It is impossible to ‘cure’, but quality of life in a sweet itch horse can be controlled with correct management.

You may notice your horse almost constantly scratching on fence posts, trees, or his stable door, using his hind legs to itch his poll, face or ears, biting wherever he can reach, as well as excessive tail swishing or grooming from his field mates. The areas that are usually most itchy are the mane and top of the tail (dock), but the face, ears, withers, rump and underneath the belly can also be affected. When he is not itching, he may appear agitated, swishing his tail to get rid of surrounding insects, head shaking, snorting and/or stamping the feet. Such agitation can also be a result of a pollen allergy or mites, for example, so itching is the main sign to look out for.

As a result of your horse itching excessively, the skin at these areas will become inflamed and sore, potentially suffering from hair loss and open sores. After repeated itching, the skin will thicken, possibly becoming flaky with dandruff and developing folds. It is especially important to keep open sores clean to reduce the risk of infection, and this is where your first aid kit will come in handy. It may be that while you never see your horse itching, these sores are present, and they can be a sign of sweet itch even if you’ve never caught him itching. Don’t dismiss your horse’s mane thinning or the top of their tail becoming thinner than it was in winter as an ill-fitting rug or a one-off itchy tail – this could be an early sign of sweet itch.

If your horse is a little quiet or tired without the other signs of sweet itch, it is very unlikely  this lethargy is due to sweet itch, and it would be advisable to consult with your vet. However, a horse or pony known to be suffering with sweet itch is likely to present as lethargic alongside the more typical symptoms, due to the immune system working in overdrive. 

The key to giving your sweet itch horse the best quality of life possible is preventing the condition from setting in for the summer months. If you do not know that your horse is a sweet itch sufferer, it is therefore important to keep an eye out for the above signs, and act quickly with the preventative measures if you believe your horse has sweet itch. 

Once the horse has become itchy it is incredibly difficult to stop them scratching – it is far more effective to stop the midges from ever coming in contact with your horse, and the best chance of achieving this is by covering your horse in protective wear, feeding an anti-itch supplement, and applying topical lotions to deter midges and soothe the skin. These preventative measures are most effective early in the year before the first midges start to appear, which varies year to year depending on the temperature and weather conditions – but generally starting in February gives the best chance of preventing the condition manifesting. Midges will be rife until the first hard frost of the autumn season, so don’t be tempted into changing your sweet itch management routine until well after the temperature has started to drop.

Midges tend to be out most at dawn and dusk – if you can stable your horse at these times, he will have less exposure to midges. Ideally, stables will be kitted out with a fan and midge screens to stop any midges from coming in, and insecticide sprays sprayed on surfaces such as stable walls, your horsebox, and equipment further reduces the risk of midges entering your horse’s living environment. Even one bite from one midge can lead to itching to the extent that the horse hurts himself, so it is worth taking every preventative that you can. 

By covering the horse in a purpose-designed sweet itch rug or sheet, we protect the horse’s skin from midge bites. An ordinary fly rug does not protect from midges in the same way as a sweet itch rug, as midges can bite through the finer material. A sweet itch rug is thicker so offers better protection. Sweet itch rugs tend to have holes for the ears, offering more protection around the poll than a rug with an ordinary neck. They also usually have a belly flap to cover underneath the horse, an area prone to bites and itching, whereas a lot of fly rugs do not cover this area. A fly mask would also be beneficial to protect the face and ears.

Midges first start to appear around March, so it is worth rugging your horse in his sweet itch rug from around February onwards. It is most important that the horse wears the rug during turnout as this is when he is most likely to be exposed to midges, but some owners rug their horse when he is in his stable too in case there are midges present. If your horse lives out, it is advisable to take the rug off daily to brush your horse and check for any sores or rubs that need treating. It is also a good idea to wash this rug regularly, as dirt and grease attracts insects. 

Midges lay eggs in wet mud, so are likely to be found in areas where there is standing water, such as around ponds, lakes and slow-moving rivers or streams. They also prefer sheltered areas such as where there are lots of trees. A thick line of trees not only attracts midges but provides a scratching post for your horse, so it may be worth fencing off thick tree lines where possible. The best environment for a sweet itch sufferer is where there is a strong breeze, as midges are not strong fliers and won’t hang around in windy weather. The ideal would be a field on top of a breezy hill with no nearby water, although this of course is not always possible.

There are many products available to help repel insects, from creams you can apply directly on to the susceptible parts of the horse, to sprays that offer broader coverage. A decent fly spray will help keep midges away, but will not prevent them entirely. A sweet itch lotion can help to prevent midges biting as well as soothe itching from existing bites, making it an essential for sweet itch sufferers. 

Supplements that help to reduce itching, promote good skin health and aid hair regrowth can be beneficial in reducing the symptoms of sweet itch. Starting these supplements early, before midge season starts, is key, to allow the ingredients to get into the system before they are needed. A general skin supplement will promote healthy skin, but a supplement designed to reduce itchiness offers a more targeted approach.

Midges and flies are less attracted to a clean coat as opposed to one that is greasy or has been sweaty, so it is all the more important to keep a sweet itch horse clean. An aloe vera, tea tree or anti-itch shampoo is likely to not only remove grease but also soothe the skin, which is sure to be appreciated by an itchy horse. Medicated shampoo also contains a mild anti-bacterial agent to promote a healthy coat. Regular use of these shampoos will help to ensure the coat and skin are as healthy as they can be, helping your horse to feel less agitated.

Wooden fence posts are the perfect scratching post for your horse and can cause open wounds if they are itching intensely. Using electric fencing instead means there is one less thing for your horse to itch on, and if they are spending lots of hours turned out, it is worth providing a turnout environment where they are less likely to be able to itch.

Your vet can prescribe prescription-only topical ointments, steroids, and anti-histamines to help combat the condition. There is a relatively new vaccine available to stunt the allergic reaction that the sweet itch horse suffers, and this may be worth discussing with your vet.

In summary, prevention is better than cure where sweet itch is concerned, and with the right management from early in the year, including using a sweet itch rug, applying insect repellent and anti-itch lotions, and creating a midge-free environment where possible, it is possible for your sweet itch horse to enjoy the summer months.