Horses, just like people, can get painful sunburns after spending the day under the sun. Though most sunburns are mild and resolve quickly, excessive sun exposure can lead to long-term skin damage and health complications.

Do All Horses Get Sunburn?
Most horses have two means of protection against the sun’s rays: their coat and the melanin in their skin.
Areas of your horse’s skin that do not have as much hair may be vulnerable to sun damage. Grey horses, white horses, and those with light-colored markings with pink skin underneath have less protective melanin in their skin than horses with more pigment.
Certain medications, including antibiotics, can make your horse more sensitive to sunlight.

Plants That Induce Photosensitivity In Horses
Your horse may develop photosensitivity if they ingest or brush up against certain plants that are commonly found in pastures.
Primary photosensitivity occurs when a horse becomes more sensitive to sunlight after ingesting certain plants, including St. John’s Wort, perennial rye, Queen Anne's lace, buckwheat, and alfalfa.
Secondary photosensitivity occurs when a horse becomes sensitive to sunlight as a result of liver damage. Ragwort, buttercup, houndstongue, kale, fiddleneck, and pattern’s curse cause liver damage over time when ingested. New or unusual skin changes after sun exposure can be a sign of liver disease and should be discussed with your veterinarian.

How To Protect Your Horse From Sunburn
It may be difficult to avoid turning your horse out in the middle of the day when the sun is shining at its brightest, but you may be able to keep them in a shady area to limit their sun exposure.
A fly sheet rated for UV protection is useful for horses that need full-body protection. For horses with white markings, a fly mask and/or socks should be sufficient.
Horses tend to have sparse hair on their nose, lips, eyelids, tips of ears, legs. You can apply equine sunscreen or zinc oxide to those areas for protection.

Treating Sunburn In Horses
Mild sunburn manifests as pinkened skin that may feel hot to the touch. The skin may become dry or peeled over a few days. You can keep sunburned skin moisturized with aloe to relieve pain and promote healing. A topical pain medication is also good to have on-hand in the summer.
Blisters, weeping sores, and changes in the appearance or texture of your horse’s skin are signs of severe skin damage and can lead to infection and even skin cancer. Seek veterinary treatment for anything beyond a mild sunburn.