Watermelon is safe for dogs to eat as long as you remove the seeds from the watermelon.
Dogs can eat watermelon in moderation, but feeding your dog too much watermelon can cause upset stomach, diarrhea and possibly vomiting.
You should only feed your dog the watermelon after you remove the seeds as the seeds in watermelon can cause possible choking and even stomach upset and digestive issues.
The watermelon is a nice refreshing treat for dogs on occasion and can also help hydrate the dog as well.