Sweet itch is a common disease of horses in summer causing them to rub their mane, tail and body. It is caused by an allergy to the saliva of the female Culicoides midge. The affected horse can be bitten anywhere; however, in most cases they will then rub their mane and/or tail. Although sweet itch usually occurs from late spring to late autumn when the midges are about, advanced cases can show clinical signs throughout the year. Diagnosis is based on the presence of compatible clinical signs and the time of year the symptoms occur; however, your vet may want to take samples to rule out other causes of an itch.
There are three main approaches to approaching/managing sweet itch: midge avoidance, soothing creams/shampoos and medications.
Avoidance is better than cure so the most effective method is midge avoidance. This includes:
- Stabling mid-afternoon to mid-morning as midges are most active dawn to dusk.
- Stable fans can help reduce midges in the stable environment.
- Use of windy fields, avoiding woodlands and areas of standing/stagnant water.
- Fly rugs, such as a Boett blankets, to provide a physical barrier.
- Fly/midge repellents, especially those with contain permethrin or cypermethrin which should last a couple of days- we can provide small bottles of these on request, which will dilute to 500ml of repellent.
In mild clinical cases, topical management through the use of soothing creams/shampoos on affected areas is generally the first port of call. While these products do not treat the problem, they improve the comfort of the affected patient. Oatmeal containing products are gentle and soothing for irritated skin. Benzyl benzoate can also help, but be very careful if the skin is broken as it can irritate these areas. There are also a number of prescription-only topical medications which can be prescribed by your vet.
Anti-histamines may/may not be of assistance in such patients. Use is off licence in horses and the response is very variable with some horses showing improvement in clinical signs whereas in others, no response is noted.
In severely affected patients, oral or injectable medications, the most efficacious being steroids, are required to control the allergy.
Finally, allergy testing is an expanding area, which can be coupled with desensitisation therapy. If you are interested in going down these routes, it is worth discussing it with one of our vets for more information as it is a complex topic. On a similar note, some people use a ringworm vaccine to try and reduce the signs of sweet itch. Some owners report a good response; however, there is limited evidence it is effective, especially as ring worm and sweet itch are two very different disease processes. Again, if you are interested in this, it is worth talking to our vets.
Ultimately the best but most difficult management method is controlling a horse’s exposure to midges; however, as per the above, there are other options available to help manage the disease when this isn’t enough.