06/26/2026
Mid Rivers has an amazing article on some of the skin conditions you may experience with your equine friends this year! https://www.facebook.com/share/p/196HnZNNww/?mibextid=wwXIfr
Deep Dive Into: Summer Sores, Sweet Itch, and Rain Rot
Tiny skin changes can tell a big story. A sore that will not heal, an itchy horse rubbing its mane, or crusty scabs after wet weather may look similar at first glance, but they are not the same problem and are not treated the same way.
For horse owners, the key is knowing what pattern you are seeing.
1. Summer Sores
Summer sores are also called cutaneous habronemiasis. They happen when flies deposit Habronema larvae into damaged skin, wounds, or moist areas instead of the larvae completing their normal life cycle in the horse’s stomach. The result is an inflammatory skin lesion that often refuses to heal on its own. UC Davis notes that these lesions can contain small gritty yellow nodules, often described as “sulfur granules,” and may recur during fly season.
What clients may notice:
A wound that keeps getting bigger, bleeds easily, drains fluid, develops proud flesh, or contains yellow-white gritty material. Texas A&M also notes that these can appear around the eyes, mouth, lips, sheath, urethra, or open wounds and may be mistaken for other serious conditions.
When to call the vet:
Call early. Summer sores often need veterinary treatment, and biopsies may be needed to rule out other conditions such as sarcoids, or squamous cell carcinoma. Treatment may include debridement, ivermectin, corticosteroids, topical medication, wound protection, and aggressive fly control.
2. Sweet Itch / Sweet Itch
“Sweet itch” is another name used for sweet itch, seasonal dermatitis, or culicoid hypersensitivity. This is not a wound problem first. It is an allergic skin reaction to biting insects, especially midges or no-see-ums. The Merck Veterinary Manual notes that affected horses often scratch and rub, leading to hair loss, abrasions, and thickened skin.
What clients may notice:
A horse rubbing the mane, tailhead, belly, or back until the hair breaks off or the skin becomes raw. The pattern is often seasonal and worse during warm months, especially around dusk when midges are active.
When to call the vet:
Call if the horse is intensely itchy, creating open sores, losing hair, or developing secondary skin infection. Management usually focuses on reducing insect exposure, using fans because midges are weak fliers, stabling during peak midge activity, fly sheets, topical protection, and medication when needed to control the allergic reaction.
3. Rain Rot
Rain rot, also called rain scald or dermatophilosis, is commonly associated with damp conditions. It is characterized by a crusting, scab formation, and matted hair.
What clients may notice:
A bumpy, crusty coat along the back, rump, withers, neck, or legs. The scabs may lift off in clumps, leaving sore or bare spots underneath. The skin can be painful, and affected horses may resent grooming, blanketing, or saddling.
When to call the vet:
Call if the scabs are spreading, painful, draining, not improving, or affecting areas where tack sits. Treatment may include gentle soaking, scab removal under veterinary guidance, antibacterial shampoos, clipping, and removing the horse from the wet environment. Also recommended is isolating infected horses, cleaning tack and grooming tools, and wearing gloves, as the organism can spread through direct contact.
Takeaway
If it is a non-healing sore with yellow granules, think summer sore.
If the horse is rubbing like crazy, think sweat itch.
If the coat feels crusty after wet weather, think rain rot.
