Good barn management, such as removing manure and standing water, is your first step in protecting your horse from gnats and other insects. Rainy weather patterns, though, can challenge even the most diligent efforts. Supplement your efforts by adjusting your horse's turnout times; protecting him with flywear; applying repellent regularly; and treating the perimeter of his barn or pasture.
Extreme sensitivity to gnats, a Cullicoides species, is referred to as sweet itch and may require veterinary intervention. Contact your vet if your horse suffers from numerous bumps or scabs and suffers from excessive itch.
Remove manure in stalls and pastures every few days; spreading it is better than a large pile accumulation for thwarting insects. Gnats need standing water to breed, so remove any in buckets and pans, and check old tires near the premises. You can't do much about mud puddles, but sometimes digging a small trench near them to facilitate drainage can help. Remove manure and urine-soaked shavings from stalls daily. Adding new wood shavings also helps.
- Cut the top off a plastic bottle or jug, about 1/3 from the top;
- Fill the bottom 2/3 of the container with apple cider or white vinegar, a few drops of lemon-scented dish soap, and enough water to fill it to at least 1/3 full or more;
- Invert the cut top so the spout is inside the liquid mix.
You can also add sugar, banana peels or anything else that attracts gnats to your trap.
Outfit your horse in gear designed for insect protection. Equine supply stores and online outlets sell sheets, boots and neck wraps for near full-body protection. You can purchase fly masks that are longer throughout the nose, and with ear covers. Ear nets are also sold individually if your horse objects to a fly mask, or for wear at night when you don't want to obstruct your horse's vision.
Commercially prepared fly sprays that contain permethrin can be effective, but you may have to apply a few times a day, particularly if your horse sweats or after bath time. Don't forget to spray his legs and belly. Apply to his face by spraying a mitt or towel and then rubbing it on his face and nose, carefully avoiding his eyes. You can use this method to apply to the inside of his ears, as well, or use a roll-on or gel form. Don't miss under his chin and in his throat area.
You can find many homemade remedies by asking your horse friends; some are made with natural ingredients while others purport to have success with a range of household products, from dryer sheets to floor cleaner. If you decide to experiment, discuss the ingredients with your veterinarian and test a small area on your horse to see if he has a negative reaction to the ingredients.
A mixture containing essential oils is a safer bet, particularly one of the commercially prepared ones. You can make your own with the guidance of a veterinarian or experienced essential oil practitioner. High levels of oils can irritate your horse's skin or cause hair discoloration, so expert advice is important.
Good oils to use include citronella, lavender, eucalyptus, geranium, neem, peppermint and lemongrass. Mix with a carrier oil that is likely to be safe, and even beneficial, for your horse's skin: olive, coconut and almond oils are good choices. Use therapeutic grade oils for maximum effectiveness.
Essential oils work as a repellent to deter gnats, but they do not kill them. Multiple applications are typically necessary.
Gnats feed from evening dusk to early morning dawn, so if possible, keep your horse inside during these hours and turn him out during the day. Erecting a fan above his stall adds circulating air to serve as an additional deterrent. Incorporating these measures with your daily barn management, protective outerwear and sprays yields greater results than just any one method.