AQUEOS - Sweet Itch

AQUEOS - Sweet Itch


Sweet Itch


Sweet itch affects many of the horse and pony population in the UK and around the world, and can be distressing for horses and owners alike! Feeling helpless in the face of sweet itch? Read on to find out what it is, how it happens and how to help. 

What is sweet itch?

Sweet itch is a summer skin disease of the horse where they become hypersensitive to insect bites. Where most horses might get small reactions to insect bites, horses suffering from sweet itch mount an exaggerated allergic response to bites from a certain biting midge. 

What are the causes of sweet itch?

The insect responsible for sweet itch is Culicoides species, although affected horses are often allergic to many types of biting insects as well as this particular one. Culicoides is a genus of biting midge and horses react to the irritants in the midge saliva rather than the actual bite itself. The saliva causes a localised inflammatory reaction in the skin when they receive a bite from the midge. 

Clinical signs of sweet itch

Clinical signs include intense pruritus (itchiness) which presents as rubbing themselves on fences, trees, and stable walls. This is usually along the mane, base and dock of the tail and back. 


Due to the constant, intense itching and scratching, horses and ponies suffering from sweet itch will start to lose hair in the mane and tail. 


Then, if the bald patches continue to be irritated by bites and itching, horses can continue to cause damage to their skin causing broken, sore, open skin lesions that can bleed and ooze – attracting even more biting midges!


In some severely affected horses, they might be so irritated by the constant itchiness, that their demeanour and even performance under saddle may be affected.


Unfortunately, as horses become irritated by the allergic reaction, they start itching, and as they itch, the skin inflammation intensifies further making the itching worse, and the cycle continues.

How do you diagnose sweet itch?

Your veterinarian can usually diagnose sweet itch by looking at clinical signs alone during a clinical examination. They will also consider the season – horses are affected when it gets warmer in spring and summer, as well as your type of horse. Ponies are more frequently affected, especially some natives such as Welsh and Shetland ponies.

Where and when do horses get sweet itch?

As we’ve mentioned previously, summer is the season for sweet itch, although it can start as early as spring. Midges will be at their worst during dusk and dawn, close to woodland or hedgerows and also near water such as rivers, ponds and lakes. A breezier, more open pasture away from trees will be better for a sweet itch horse as midges can’t fly as well in the wind and therefore numbers will be lower. Keep this in mind when you’re looking at grazing locations and stabling schedules for your horse during the summer. 


Sweet itch treatment

Always consult your veterinarian early on to make sure your horse isn’t itching for other reasons such as lice or pinworm, as these will both need to be treated completely differently. 


The key to treating sweet itch is excellent insect control. Using strong, effective insect repellent that includes DEET is crucial to warding off those midges. It can be sore if applied directly to areas of broken skin so be careful, but you can apply it adjacent to those areas. Remember, although the mane and tail are often the most severely and obviously affected regions, always apply fly repellent to the whole body as any new bites, whether that’s on the belly, legs or ears will contribute to the overall irritation and suffering. 


Physical midge barriers

On any broken and sore skin, barrier creams to form a physical barrier to the midges as well as providing a soothing and healing environment can be very effective. Horse owners often go for something like Sudacream but your veterinarian might have their own formulation that they recommend. Before applying a cream to your horse’s inflamed and cracked skin, make sure you clean the whole area gently with warm salt water and then apply a gentle cleaning solution such as an Animal First Aid Spray in order to stop the area harbouring dirt and bacteria underneath the layer of cream. 


When it comes to physical barriers, your next step will be to invest in a fly rug that covers the mane and tail and fits snuggly enough to prevent midges from sneaking into any gaps and accessing your horse’s skin underneath. Ideally, the fly cover should cover them from head to tail, including ears and belly as they can be affected body-wide, not necessarily only mane and tail. 


Environmental Management 

Finally, environmental management is extremely important to consider in the overall management of sweet itch. As we mentioned before, woodland and standing water such as ponds and lakes are prime midge breeding spots, exposing your horse to a much higher population. If you’re able to choose, a paddock which is breezier, more open, and as far away as possible from trees and water is far more preferable. 


Furthermore, knowing that midges are out in their thousands at dawn and dusk, try to make sure your horse is stabled during these times. This usually means, inside by 4 pm and out after 8 am. 


Shampoo treatment

You may want to shampoo your horse with a soothing oatmeal shampoo or a specifically formulated anti-itch shampoo about once per week to relieve some of the itchiness and break the itch cycle. 


Medicated treatment

If you’ve implemented all the above in the management of your horse and you’re still not getting results, you may want to talk to your veterinarian about anti-inflammatory treatments such as corticosteroids. This may provide short-term relief to the itching and help to break the itch cycle if nothing else has yet, but it isn’t a long-term solution.


Your vet might also prescribe antihistamines, however, there are no antihistamines that are licensed in horses so always ask for advice from your vet to talk about possible side effects and doses. In my experience, not all horses respond to antihistamines similarly so where one horse might have a great response and find relief from antihistamines, another might not for no obvious reason. 


How to prevent sweet itch

If you know your horse is prone to sweet itch, then you’re in a great position to help prevent the disease from getting to a point where it needs medical intervention early on. As soon as the weather starts to warm up, make sure to get that fly rug on straight away. This might mean from March onwards depending on your local climate. 


In addition, if you ever move livery yards or if you’re lucky enough to keep your horse at home and move properties – be aware of surrounding woodland or nearby standing water to help you make the best decision for where to graze your horse. 



Sweet itch is a notoriously difficult disease to control, and the constant irritation must be unbearable for horses and ponies who suffer badly from it. Pre-planning and early environmental, rugging and stabling management are crucial to setting your horse up for a summer without itching.


This article was written by Dr Alice Barker BVSc MRCVS.