Question
My gelding has been diagnosed with sweet itch. He seems especially itchy and distressed when he comes in from the pasture, vigorously scratching his mane and tail. I tried an elimination diet by feeding a couple weeks of just hay and no pasture versus a couple weeks of hay and a few hours in a new field with rich green grass. Is he allergic to the grass? Would a grass allergy cause sweet itch? What do you recommend?
Answer
Based on your description and the veterinarian’s diagnosis, it sounds like your horse is being affected by the insects that live in the pasture environment as opposed to the grass in the pasture.
Pruritus in horses is the uncomfortable itching sensation that results in intense scratching and rubbing of skin, mane, and tail. Some horses have a hypersensitivity to bites from Culicoides midges, specifically a reaction to the protein in their saliva, and this is referred to as sweet itch. The midges are active during warmer months and breed in wet or muddy environments. It is best to avoid turnout during dusk and dawn hours as that is the insect’s preferred feeding time. Keeping horses stalled with fans is a good way to minimize biting, which in turn will reduce itching.
One effective treatment has been the use of short-acting corticosteroid injections that aim to block the antibodies that prevent the inflammatory response from occurring. Immunotherapy treatments that suppress the immune response to midge saliva have been useful. Other research has been performed in hopes of alleviating sweet itch.
From a dietary standpoint, there has been some success feeding omega-3 fatty acids to help reduce inflammatory response and improve immune function. EO•3, a product developed by Kentucky Equine Research (KER) containing DHA and EPA, two long-chain omega-3 fatty acids, is more efficiently used as precursors of local hormones than plant-based sources of omega-3s such as flaxseed.
Each horse responds differently to treatments, so I recommend working closely with a veterinarian to find solutions.
