Cats can drink watermelon juice. Watermelon juice can help cats relieve heat and replenish body moisture. However, cats cannot be fed too much watermelon juice at one time, and it is best to remove the watermelon seeds before squeezing the juice, otherwise the cat will suffer from digestive problems. Bad food, diarrhea and other conditions can even lead to diabetes in cats. And if your cat doesn’t want to drink watermelon juice, don’t force it.