Sweet Itch in Horses: Causes, Symptoms & Treatments

Horses, ponies, and donkeys often suffer from sweet itch, a distressing allergic condition common in the warmer months. While all breeds can be affected, cob types tend to experience it more severely than some warm-blooded breeds such as Arabs and thoroughbreds. Sweet itch causes intense itchiness and irritation, leading to discomfort, stress, and sometimes secondary infections if left untreated.

What Causes Sweet Itch in Horses?

Sweet itch arises from an allergic reaction to the saliva of biting midges, specifically the Culicoides species, which are prevalent in the UK and many parts of the world. Most horses are unaffected by midge bites, but those sensitive develop an allergic response. These tiny insects breed near stagnant water and are most active from spring through autumn, especially during dawn and dusk.

The reaction worsens with repeated exposure over the years, increasing a horse's sensitivity to midges. The saliva contains several potentially allergenic compounds, though which specific compound triggers the reaction can vary.

Recognising the Symptoms of Sweet Itch

Symptoms usually arise during peak midge activity in spring to autumn and can include:

• Excessive itching, primarily along the mane crest and tail base, but also on the back, head, ears, and other body areas.
• Hair loss, bald patches, and broken hairs from constant scratching.
• Inflamed, scaly, crusty, ulcerated, or weeping skin lesions.
• Behavioural signs such as vigorous tail swishing, head shaking, rubbing against objects, and restlessness.
• In chronic cases, thickened, darkened, and calloused skin that may prevent regrowth of hair.
• Secondary bacterial or fungal infections due to open sores.

Preventing Sweet Itch: Practical Tips

Preventing midge bites is essential as allergic reactions tend to persist once triggered. Here are effective strategies to minimise exposure:

• Use insect repellents regularly. Products containing citronella or veterinary-approved equine fly repellents help but require frequent application.
• Avoid grazing near stagnant water such as ponds or boggy fields where midges breed.
• Use protective barriers like fly sheets and fly masks designed for horses to reduce biting insect access.
• Stable horses during peak midge activity times, typically late afternoon to early evening (around 4–9pm).
• Choose grazing areas exposed to gentle breezes, as midges struggle to fly in winds above 5mph.
• Some owners supplement diets with oils like linseed, though evidence of effectiveness for sweet itch is limited.

Treating Sweet Itch: Options and Considerations

While there is no definitive cure, several treatments can alleviate symptoms and improve quality of life:

• Topical antihistamine creams to reduce itching, although these may be costly over time.
• In severe cases, veterinarians might prescribe corticosteroids to control inflammation, which should be used cautiously due to potential side effects.
• Antibiotics can be necessary to treat secondary infections from open sores caused by intense scratching.
• Natural soothing products like lavender, chamomile, or tea tree oil shampoos may reduce skin irritation.
• Immunotherapy or desensitisation treatment is an emerging approach where the immune system is gradually trained to tolerate the allergen; however, it's still experimental and not suitable for all horses.

Living with and Managing Sweet Itch

Owners should regularly monitor their horses through midge seasons, maintain preventive measures, and seek veterinary advice promptly if symptoms worsen. Keeping affected horses as comfortable as possible and preventing self-inflicted skin damage plays a critical role in management.

Remember, responsible horse care means awareness of conditions like sweet itch and early intervention to preserve your equine's health and wellbeing.