Preventing Horse Sunburns: The CausesBy Jeffrey Rolo
While most of us are intimately familiar with the painful effects of a sunburn and thus take actions to shelter ourselves from the sun's strong effects, we often forget that our beloved horses can also be struck hard with this painful affliction if exposed to the sun too long. As such, it's important to monitor our horses and their surroundings so that we can minimize or prevent equine sunburn before it takes root.
One of the reasons that many horse owners don't automatically connect horses with sunburns is because the sun's rays don't affect all horses equally. While darker-haired horses generally don't experience much more than some bleaching of their coat, their lighter-haired brethren that lack significant levels of pigment within their skin are particularly susceptible to sunburns, which is why this affliction is more prevalent among light-colored horses and/or breeds such as Appaloosas, Paints and Pintos.
What should we be looking for?
Sunburned horses demonstrate the same symptoms as we do. Initially their skin will take on an angry pink/red color, and if the condition becomes more severe eventually some swelling could occur, the affected areas could break out in blisters, the skin can become dry and cracked, and hair loss can occur. In serious cases equine sunburns can even lead to colic or liver damage.
Which areas are generally most vulnerable to sunburn?
The horse's muzzle, eyes, ears, white socks, shoulder blades, vulva and any hairless patches will usually prove to be the problematic areas on a horse, though it's not impossible for the harsh sun to also affect other areas with prolonged exposure. If your horse possesses a light coat or a blaze on his forehead, I recommend watching his nose carefully. Chances are good his nose will show the first signs of sunburn, so if you notice it developing a pink hue then you know it's time to take preventative measures.
Is the sun the only factor we need to take into account?
No! While it's true that sunlight is the ultimate culprit in causing equine sunburns, photosensitization can make a horse particularly vulnerable to the sun's rays. Photosensitization basically causes horses to develop an extremely negative reaction to light, such that sunlight that would normally not bother them would suddenly start causing serious burns.
Two primary causes for photosensitization are medicines and plants, so let's briefly cover the medical end of things first. If you notice your horse begins developing serious sunburns while being medicated, there's a chance that the medicine itself is making your horse extra vulnerable. Call your vet and discuss the medicine with him… see if he's aware of photosensitization being a possible side effect of the medicine. Tetracycline in particular has been linked with photosensitization, so be very careful about exposing your horse to sunlight or strong light if he's taking any tetracycline antibiotics.
Various plants contain chemicals which can lead to varying levels of photosensitization (such as ragwort and buckwheat), but one type of clover in particular that you should watch out for is Alsike clover. Alsike clover contains a toxin that can cause liver damage, and while I'll spare a droning scientific explanation of the damage one of the by-products of the damage is a build-up of chlorophyll within the horse's bloodstream. This chlorophyll build-up, when exposed to strong light, can cause significant damage to the horse's skin.
Alsike grows within grass and hay fields, particularly in the upper Midwest and North Central Pacific states of the U.S. (Alsike also grows in Canada.) Since Alsike is vulnerable to prolonged high temperatures or drought conditions, you are unlikely to find it in Southern states.
If you notice your horse becomes particularly susceptible to the sun after being pastured, it would be a good idea to walk around your pasture and search for signs of Alsike. You can find some photos of this plant here:
If you purchase hay gathered from regions in which Alsike grows, your horse could conceivably become poisoned from the hay itself. This would be rather uncommon since the horse would need to ingest a significant level of Alsike before experiencing Alsike poisoning – it's not a case where ingesting a single leaf will doom your equine partner. Usually alsike poisoning becomes a threat when it reaches 20% of the horse's diet.
Now that we have covered some of the primary causes of horse sunburns, let's head on over to Part 2 of this series and learn how we can combat equine sunburn.