Watermelons are a favorite treat during hot summer days. It's pretty natural to want to share a treat with your friends—your equine friends included. While rinds don't taste that great to us (unless you pickle them or cook them in a stir-fry), your horse will probably crunch them down with zeal. But are those watermelon rinds safe for your horse to eat? The answer is yes. In small quantities, watermelon rind is fine. Your horse can eat the ripe part, too, seeds and all. Some may not like melon, while others will be wild about it.
Fruit Sugars in Watermelon
One thing people worry about when feeding watermelon to their horse is the seemingly high sugar content. As its name implies, watermelon is mostly water. In fact, a serving of watermelon is about 90 percent water. That means roughly 10 percent of a watermelon is sugar. In a cup of diced watermelon, there is about 0.5 grams of fiber and 10 grams of sugar. There are also a few vitamins and minerals in there—mainly vitamins A and C, magnesium, and phosphorus.
Sugar occurs naturally in all plants. Even carrots—a favorite root vegetable fed to horses, quite often by the bucketful—can contain about 6 grams of sugar per cup of a diced root. A horse's natural food, pasture grass, has sugar, too. At certain times of the year, the amount of sugar in grass can be more than 25 percent. Over the course of a day's eating, a horse will eat several pounds of sugar. This presents a problem only when they eat too much, as too much sugar in their grass can lead to laminitis and colic. As you can see, your horse would have to eat a lot of watermelon before the sugar would become a problem.
Another thing people worry about is potential toxins in the rind. The watermelon is a member of the cucumber family, and most of us wouldn't think twice about eating the skin of a cucumber or feeding it to our horse. There is no obscure toxin in watermelon skin or rind that is a danger only to horses, and, as noted, watermelon rind can be pickled and eaten by humans.
Some horse owners worry about the seeds. There are toxins in the seeds of many fruits, but the quantity of toxin is so minute that it's unlikely to cause any problems. Watermelon seeds can even be roasted for a traditional tasty treat. Also, because the seeds are so tiny, there is little chance they will cause choking, or you can simply buy seedless watermelon to avoid any concerns with seeds.
The one thing you might want to do before you slice into your watermelon is to wash the outside. The rind may be sprayed with pesticides or herbicides, or it may carry bacteria such as E. coli, and these can contaminate the flesh as you draw the knife through. That's not good for you or your horse. Wash the entire outside of the rind with cool water and a scrub brush before cutting into the melon.
Everything in Moderation
While occasionally feeding your horse small quantities of watermelon or sharing your uneaten rind is okay, a really large quantity of sugars may lead to colic or other problems for your horse's gut, so you might not want to toss a large quantity of half-ripe melons from your garden into the pasture. Also, chunks of any improperly chewed food can cause choking in horses. The watermelon rind should be cut into small, easy-to-chew into pieces. Otherwise, there's no reason your horse can't enjoy this summertime treat just as we do: in moderation.
The Role of Nutrition in Horse Colic and Laminitis. Extension Foundation, United States Department of Agriculture.