Feeding Watermelon to Your Horse
Watermelon Toxins
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.