For horses diagnosed with sweet itch (SSRD) · Skin health
Sweet itch and Culicoides midges — where does my horse get bitten?
Your horse has been diagnosed with sweet itch — also called Summer Seasonal Recurrent Dermatitis (SSRD). That can feel overwhelming. This sheet explains one of the most misunderstood aspects: where on the body the midge bites, and why this matters for protecting your horse.
Where the midge prefers to bite
Different midge species prefer different parts of the body, but any unprotected skin is a potential bite site:
| Zone | Midge species | Where on the body | Note |
|---|---|---|---|
| Dorsal zone (classic SSRD) | C. obsoletus group and C. pulicaris | Mane, poll, withers, back, rump, tail base | The most common pattern in NL / BE / UK |
| Ventral midline | Culicoides nubeculosus | Belly, sheath / udder, inner thighs | Often seen alongside dorsal signs |
| Flanks and shoulder | Any species — opportunistic | Flanks and shoulders | Flank itching does not exclude sweet itch; unprotected skin = bite site |
| Face and lower legs | Any species | Face and lower legs | Especially where the rug does not cover; more common without a full-coverage rug |
Important — about the itching pattern
You may have been told: 'your horse itches on the flanks, so it cannot be sweet itch.' That is not correct. Midges bite wherever they can reach your horse. A horse without a full-coverage rug, or standing near hedges or water at dusk, can be bitten anywhere — including the flanks, face and lower legs.
The most reliable signs of sweet itch are: a seasonal pattern (worse in spring and summer, better in winter), breed predisposition (some breeds are much more susceptible), and improvement when midges are kept away. Distribution pattern alone does not confirm or rule out the diagnosis.
What this means for management
- ① The most important step: a sweet-itch rug must cover all the bite zones — mane, neck, back, belly and tail base. A neck-only rug leaves the belly and rump exposed; midges find the gaps. Check the fit daily.
- ② Timing matters: midges are most active at dawn and dusk — stable your horse during these periods. In NL/BE summers, dusk can last until 10pm. A stable fan greatly reduces midges indoors (they cannot fly in moving air). Avoid waterside and sheltered, hedge-lined paddocks.
- ③ Repellents: apply to areas the rug does not cover — face, lower legs, around the rug edges. Reapply every 2–4 hours in high-midge conditions. Repellents support the rug — they do not replace it.
- ④ Diet and the immune system: diet cannot cure sweet itch but can help reduce the severity of the reaction. Good hay, balanced minerals and omega-3 (fish oil) help lower the background inflammation. Changes take 4–6 weeks to build — start before midge season if you can.
A note from EVN
Sweet itch is a lifelong condition in most horses, but very manageable. The horses that do best are those whose owners understand what is happening and act on it consistently. If something doesn't seem to be working, or you're unsure about a recommended product, please ask — EVN gives honest, evidence-based answers.
This is general information. It does not replace the individual feeding plan your EVN vet prepares for your horse after assessing it.