Sweet itch is a prevalent equine skin condition triggered by insect bites, causing severe itching and discomfort. Approximately 2.8% to 10% of horses are affected by sweet itch globally, depending on the region and climate. In the UK alone, around 2.8% to 5% of horses are reported to suffer from this condition annually. Globally, millions of horses could be affected annually in tropical and subtropical areas where exposure to biting insects is prolonged, often for 9-10 months.
This blog dives into the causes, key symptoms, and top treatments, including soothing lotions, targeted injections, and beneficial supplements. If you’re seeking reliable products or practical prevention tips to keep your horse comfortable, this comprehensive guide has all the insights you need. Let's start with the basics.
What is Sweet Itch in Horses?
Sweet Itch is a common term for Summer Seasonal Recurrent Dermatitis. It is an allergic response to the saliva of biting midges, sandflies, and one kind of blackfly. It is a condition that strikes all horse breeds, but pony and cob types seem more prone than others.
Sweet itch is also believed to be hereditary and because of that, it is not recommended to breed from an animal that suffers from this condition. Sweet Itch is a seasonal complaint when midges are most active between April and early November, particularly on calm, humid days, biting mostly in the early morning and late afternoon.
Symptoms of Sweet Itch in Horses
Symptoms include severe itching, hair loss, skin thickening, and flaky dandruff. Weeping sores, sometimes with a yellow crust of dried serum may occur which can result in a secondary infection if not treated. 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 may also suffer.
The horse may swish its tail vigorously, roll frequently, and try to scratch on anything within reach. It may pace endlessly and seek mutual grooming from field companions.
Sweet Itch may cause a marked change in temperament; the horse may become agitated, impatient, and lacking concentration when ridden. The presence of flying insects often aggravates these changes and can lead to head shaking.
Horses affected with Sweet Itch start showing symptoms at one to five years and often have the first signs of the disease in autumn.
Causes of Sweet Itch in Horses
Sweet Itch is a form of delayed hypersensitivity, an allergic reaction, and the symptom results from an over-vigorous response by the horse's immune system. To repel invading insect saliva, the horse attacks some of its skin cells, and the resulting cell damage causes the symptoms described as Sweet Itch.
Both the Culicoides midge and the larger, hump-backed Simulium equinum, which is a blackfly, cause the disease. Each has a preferred feeding site; Culicoides tend to be body feeders and Simulium is most often ear feeders.
Management of sweet itch in horses
Currently, there is no treatment for Sweet Itch. Once a horse develops the allergy it generally has it for life and every spring, summer, and autumn are distressing periods for horse and owner alike. The animal's comfort and well-being are down to its owner's management, on the advice of their veterinarian.
If you suspect Sweet Itch infection, consult your vet to confirm the diagnosis and discuss a targeted approach for managing the problem, based on the circumstances.
Tips to Reduce The Attack
- Haul the horse to a more exposed, windy location.
- Pasture well drained and away from muck heaps.
- Stable at dusk and dawn when the midges are on their feed peak
- Use an insect repellent.
- Use a summer sheet, preferably with complete neck and tail covers to protect the base of the mane and tail. Specially manufactured anti-midge rugs are now available.
- Add garlic to the diet. Though not scientifically proven it helps
- Magnesium-rich mineral blocks have also been reported as causing a marked improvement in some animals.
- Use an insecticide like Benzyl Benzoate.
Minimise Allergic Reactions
- Depressing the immune system with corticosteroids (e.g. by injection of 'Depo-Medrone' or 'Kenalog', or in tablet form as 'Prednisolone') may bring temporary relief. However, there can be side effects, including laminitis.
- The use of antihistamines may bring some relief but high doses are required. This might make the horse drowsy.
- Use soothing lotions on the affected areas. Soothing creams such as Calamine Cream or 'Sudocrem' can help ease and reduce inflammation, but they will not prevent further midge attacks.
Sweet Itch Treatment Products
There are plenty of effective options to alleviate itching and protect your horse from further irritation. It includes soothing lotions and insect repellents to specialised supplements and veterinary-recommended injections. Here are the top 3 Sweet Itch Treatment Products to try out:
Switch Equine:
It is a ready-to-use solution that should be applied at 1 ml per 10 kg body weight to a maximum of 40 ml. The measured dose is used in about equal parts to the mane and rump while avoiding the saddle area. Treatment should start at the beginning of the sweet itch season, with retreatment as needed. If horses and donkeys are to be groomed, apply Switch after grooming.
Killitch
It is a specifically designed preparation used to treat horse and pony cases of sweet-itch. Killitch can be used as a form of prevention against sweet-itch and skin irritation or as a treatment for irritation and infection after it has set in. The Killitch formulation offers protection against bacterial infection as well as midge-repellent properties.
Sweet Itch Lotion Equine:
A clear oily solution containing Piperonyl Butoxide (100%) 0.5% v/v added as Piperonyl Butoxide BP (Vet), Pyrethrum Extract BP (Vet) 0.4% v/v. Apply the lotion before the start of the season when the Culicoides midge becomes active (April).
First application:apply liberally to the mane and tail with a soft brush, parting the hair on the mane and tail to apply the lotion to the skin. Subsequent applications: Top up once or twice daily with a smaller amount of lotion throughout the spring, summer, and early autumn. After shampooing the mane or tail, a heavy application should be made again.
Conclusion
The good news is that Sweet Itch only affects a small minority of animals and is not an infection that can pass from horse to horse. Unfortunately, once a horse or pony has become sensitive to these insects it will always remain so.
Sweet Itch can be both debilitating and unsightly. It prevents the animal from being used for showing and the resulting sores may prevent or limit its ability to work or be ridden in the summer. Very often these animals are sold during the winter months when the condition is not active and the problem is passed on to another unsuspecting owner.
Animals with this condition should always be warned to their purchasers because they require special attention; thus, they should be taken to experienced homes with suitable facilities.
Frequently Asked Questions
What is Sweet Itch?
Sweet Itch is a seasonal allergic reaction in horses caused by the saliva of biting midges, sandflies, and blackflies. It results in severe itching, hair loss, and skin damage, most commonly affecting the mane, tail, and other areas. It is more common in ponies and certain horse breeds.
What causes Sweet Itch in horses?
Sweet Itch is a hypersensitive immune response triggered by the bite of insects like Culicoides midges and Simulium blackflies. These insects inject saliva into the skin, causing an allergic reaction, which leads to itching and inflammation as the immune system attacks the horse’s skin cells.
What are the symptoms of Sweet Itch?
Common symptoms of Sweet Itch include severe itching, hair loss, skin thickening, and flaky dandruff. Affected areas may also develop sores that can become infected. The horse may show signs of agitation, excessive tail swishing, and rolling to relieve discomfort from itching.
How can I manage Sweet Itch on my horse?
While there is no cure, management of Sweet Itch includes reducing insect exposure, using insect repellents, and providing soothing treatments like corticosteroids or antihistamines. Special rugs, stable adjustments, and insecticides can help reduce the severity of symptoms during peak midge activity.
Can Sweet Itch be prevented?
Prevention of Sweet Itch involves minimizing exposure to midges, such as stabling horses during peak midge activity (dawn and dusk) and using protective clothing like anti-midge rugs. Although garlic and magnesium-rich minerals are often recommended, their effectiveness lacks scientific validation.
How does Sweet Itch affect the horse's temperament?
Horses with Sweet Itch may become irritable, and agitated, and have difficulty concentrating when ridden due to the discomfort caused by itching. Flying insects can exacerbate these behavioral changes, leading to excessive head shaking and restless pacing.
Is Sweet Itch contagious?
Ans: Sweet Itch is not contagious and cannot be passed from horse to horse. However, it is a lifelong condition once a horse develops the allergy, meaning they will suffer from it every year during the insect season. Horses with Sweet Itch require special care and attention from experienced owners.
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